Аннотация (русский):
Many cheese manufacturers still have not utilized cheese whey that damages to the environment as it is directly been drained into waters. Cheese whey can be used as active packaging material to prolong the shelf-life of food products. Fermented cheese whey contains bioactive peptides which are able to improve the functional properties of cheese whey as an antimicrobial agent. The combination of cheese whey with polysaccharides, lipid, and other additional ingredients can improve the physical characteristics of the active packaging in the form of edible film. Around 20-45% of plasticizer will expose the film formed. Cheese whey with agro-industrial waste starch-based formulation can be used as an alternative way to produce an antimicrobial edible film as an active packaging. The film has shown acceptable physical characteristics and high antimicrobial activity, which makes it possible to extend the shelf life of food products. An advanced process, for example, the use of transglutaminase enzyme and Candida tropicalis mutant, is also effective. The result of that is the formation of the essential compound which can improve the active packaging quality. The utilisation of cheese whey and agro-industrial waste based on starch contributes significantly to the environmental conservation.

Ключевые слова:
Whey, protein, shelf-life, packaging, antimicrobial, edible film, fermentation, environment

INTRODUCTION
Cheese production process has significant impact on
the environment. One of damaging factor is the disposal
of cheese by-product. Cheese making process produces
large amounts of by-product called cheese whey, which
is almost 90% of used milk [1]. It implies if one batch
of cheese production uses 100 L o f m ilk, 8 0–90 L of
cheese whey will be produced [2]. Although it is wasted,
30% of cheese whey still has been utilised as animal
feed and fertiliser, while the rest has thrown away to
the rivers or seas [3]. Cheese whey is able to damage the
environment due to its characteristics. Cheese whey has
high biochemical oxygen demand (BOD) and chemical
oxygen demand (COD), which is more then 35000 and
60000 ppm, respectively [4]. Thus, 4000 L of whey from
the cheese industry can damage the environment to the
same extent as faecal waste from 1900 humans [5].
On the other hand, whey has a valuable chemical
composition and contains 55% of total nutrients in
milk [6]. Whey contains (w/w): 93.7% of water, 0.1–0.5%
fat, 0.8% protein, 4.9% lactose, 0.5–0.8% ash, and
0.1–0.4% lactic acid [2]. Functionally, the beneficial
effect of whey on the human health is due to
immunoglobulin and glycoprotein, such as lactoferrin
and transerin, as well as enzymes – lysozyme and
lactoperoxidase. All of these components contribute
to human immunity and have an antimicrobial activity
against allergy reaction [7, 8].
Cheese whey has been utilised in various ways.
About 70% of whey is processed into whey powder
that can be used in pastry, ice cream, sweets, glazes,
sugar dressing, jams, and melted cheese industry [3, 9].
Whey is used as a food ingredient because of its gelling,
emulsifying, antimicrobial properties, good solubility,
viscosity, nutritional value, as well as the ability to
reduce allergenicity [2, 10]. Unfortunately, it is difficult
to utilise whey for cheese manufactures [11]. One of the
causes is high cost drying process of whey. Therefore, the
search of alternative whey processing is of great interest.
Organic compounds of whey are a potential
biomass to be utilised as bio-energy. Bioethanol can
be made from whey through fermentation by using
Kluyveromyces fragilis var marxianus [11–13]. Lactose,
12
Dinika Isfari et al. Foods and Raw Materials, 2019, vol. 7, no. 2, pp. Х–Х
whose content in whey is 4.5–5%, acts as a carbon
source for ethanol fermentation. The fermentation
also can result in various bioproducts, such as ethanol,
biogas (methane), organic acids (acetic, propionic, lactic,
citric, and gluconic), amino acids (glutamic, lysine,
and threonine), vitamins (B12 a nd B 2), polysaccharides
(gum, dextran, and gellan), lipids, enzymes
(polygalacturonase), and others (calcium magnesium
acetate, butanol, and glycerol) [11].
The fermentation of whey leads to other compounds
which have high functional use, such as bioactive
peptides. Native whey has minor bioactive compounds
such as lysozyme, lactoperoxidase and lactoferrin that
are reported to have antimicrobial activity towards
pathogenic bacteria [7]. Fermentation causes protein
hydrolysis – by a microorganism which releases
bioactive peptides from protein molecules or by a
digestive enzyme, such as proteases [14, 15].
Cheese whey can also be utilised as biodegradable
packaging material, such as edible film. Such a film is
safe to consumers and environmentally friendly. It is also
expected to extend the shelf life of food products because
it protects them from gases, such as oxygen, carbon
dioxide, and ethylene, as well as from water loss [16–18].
The use of the edible film as a food packaging
material is expected to reduce plastic waste. Annually,
Indonesia produces 3.22 million metric tons of plastic
waste. It is the second largest plastic waster after China
that produces 8.82 million metric tons. The use of plastic
has rapidly increased since the development of plastic
commercialisation in the 1930s and 1940s. It reached
288 million metric tons of global plastic resin production
in 2012 [19].
The high rate of population growth has caused
an increase in food demand. This has resulted in an
increasing use of plastic, which contributes to the
economic benefits [20, 21]. Food industry still widely
uses non-degradable plastic as a food packaging
material. However, non-degradable plastic, such as
polyethylene (PE), has an immensely slow degradation
time under natural environmental conditions [22–24].
Thus, food industry indirectly affects the environment.
The utilisation of cheese whey to produce bioproducts,
such as edible films, would be a potential
course of action to protect the environment. Cheese
whey fermentation can be applied to enhance the
antimicrobial effect and the packaging ability of the
edible film produced in order to extend the shelf life of
packaged food. The aim of this paper was to review the
potential of fermented cheese whey in the produce of
edible films and active packaging systems.
STUDY OBJECTS AND METHODS
The paper was written with non-research
methodology based on literature reviews from various
sources.
RESULTS AND DISCUSSION
Fermented cheese whey. The protein content in
milk is 3.5% which is, in turn, composed of 80% of
casein (α-, β-, and k-caseins) and 20% of whey proteins
(β-lactoglobulin, α-lactalbumin, and others). Several
proteins in milk have an antimicrobial effect as shown
in Table 1 [31, 33–38]. Whey contains biological active
substances, such as enzymes, trace elements, and
immunoglobulins which contribute to the good health [25].
Table 1 Antimicrobial peptides in milk
Source Protease Peptide Target
Antimicrobial peptides from casein
Bovine αs1-casein Chymosin Caseidin Gram-positive bacteria
Chymosin,
Chymotrypsin
Isracidin αsl-CN (f l–23) Staphylococcus aureus
Bovine αs2-casein Trypsin Casoidin-I f (150–188) Gram-positive and gram-negative bacteria, yeast
Chymosin Casoidin-I f (181–207) Gram-positive and gram-negative bacteria
β-Casein Trypsin and
chymotrypsin
β-Casein-derived peptides Enterococcus faecium, Bacillus megaterium
Antimicrobial peptides from whey
β-lactoglobulin Trypsin β-lactoglobulin f (15–20) Gram-positive bacteria
Trypsin β-lactoglobulin f (25–40) Gram-positive bacteria
Trypsin β-lactoglobulin f (78–83) Gram-positive bacteria
Trypsin β-lactoglobulin f (92–100) Gram-positive bacteria
Lysozyme Synthetic Lysozyme D52S-Lz (from yeast
in egg white)
Staphylococcus aureus and Bacillus subtilis
Lactoferrin Pepsin Lactoferricin B f (17–41) Escherichia coli, Listeria monocytogenes,
viruses, fungi
Pepsin, chymosin Lactoferricin B f (1–16) E. coli, Micrococcus flavus
Pepsin Lactoferricin C f (14–42) M. flavus
Synthetic Lactoferrampin/BL fampin f (268–284) C. albicans, E. coli, Bacillus subtilis,
and Pseudomonas aeruginosa40)
13
Dinika Isfari et al. Foods and Raw Materials, 2019, vol. 7, no. 2, pp. Х–Х
Fermented whey is known to exert antimicrobial
properties. For example, Bacillus licheniformis can
produce 3200 AU/mL of bacteriocins from 70 g/L of
cheese whey. This amount can count over 4000 AU/mL
if cheese whey increases up to 120.4 g/L (with initial
pH of 7 and incubation temperature of 26–37°C). [26].
Bacteriocins are a bacterial peptides which are able to
inhibit or kill microorganisms [27]. Other lactic acid
bacteria, such as Lactococcus lactis, Lactobacillus
casei, and Leuconostoc mesenteroides, also can produce
bacteriocins in response to whey fermentation [28–30].
Besides bacteriocins, fermented whey contains
bioactive peptides which also have antimicrobial
activity. Bioactive peptides defined as inactive fragments
of precursor protein sequences. Proteolytic enzymes
can release the fragments, and they can interact with
selected receptors and regulate the body’s physiological
function [31]. Table 2 demonstrates bioactive peptides
contained in whey protein [50–55]. β-lactolobulin,
α-lactoalbumin, immunoglobulin, bovine serum
albumin, bovine lactoferrin, lactoperoxidase and minor
proteinaceous, such as glycomacropeptide, are released
from k-casein during enzymatic cheese making [32].
Along with antimicrobial effect, whey bioactive
peptides act as immunomodulatory agents that regulate
cell-mediated and humoral immune functions [31].
In addition, bioactive peptides inhibit angiotensinconverting
enzyme (ACE) that splits angiotensin I to
angiotensin II, an active peptide hormone. These peptides
are able to inhibit ACE and control the increase in blood
pressure [39]. Opioid peptides influence the central or
peripheral nervous system that involved in hypotension,
reduced appetite, fluctuating body temperature and
alteration of sexual behaviour [40, 41]. Also, peptides
with antioxidant activity which can protect the cell from
free radicals has been detected [42].
Bioactive peptides can be released in three ways:
gastrointestinal digestion (in vivo), fermentation
(in vivo), and hydrolysis (in vitro) [31]. Release of
bioactive peptides in gastrointestinal tract is the result
of enzymatic action. The enzymes are pepsin, trypsin,
or chymotrypsin. Pepsin, which is produced from
pepsinogen by hydrochloric acid (HCl), converted
protein to peptides and amino acids [43]. Other enzymes,
such as alcalase and thermolysin, can also stimulate
gastrointestinal digestion to produce ACE inhibitory
peptides, as well as anti-bacterial, anti-oxidative,
immunomodulatory, and opioid peptides [44–49].
Other ways to produce bioactive peptides are
microbial fermentation and hydrolysis. For microbial
fermentation, such LAB as Lactococcus lactis and
Lactobacillus helveticus are used. Microbes will
use distinct intracellular peptidases including endopeptidases,
amino-peptidase, di-peptidase, and
tri-peptidase [33]. Hydrolysis of protein molecules can
is performed by proteinases, which leads to the release
of bioactive peptides. Proteinases are obtained from the
secretion of the bacterial and fungal sources [31].
Bioactive peptides produced from fermented whey can
be purified to enhance their functional activities. Stepwise
filtration can be carried out to extract bioactive peptides
after fermentation. Afterwards, the extract is centrifuged
at 7000 rpm for 10 min in a refrigerated centrifuge
to obtain supernatant. The supernatant is filtered
through 0.45 μm and then through 0.22 μm syringe
filters. Ultrafiltrate of bioactive peptides of 10 kDa
and 5 kDa in size can be obtained after passing through
the 10 kDa and 5 kDa MWCO membranes [56].
Edible film production. Food products usually
have a short shelf-life. In order to prolong it, most of
manufacturers uses food packaging. A packaging system
should protect the product from contamination during
handling, storage, and sale until it reaches retailers and
consumers [57]. Non-degradable packaging still has
widely applied by food industry. The US Environmental
Protection Agency (EPA) reports that 31% of municipal
solid waste (MSW) is packaging waste [58]. Edible
films as a packaging material can be an effective
solution of reducing waste because of their degradable
characteristics [57].
The ideal edible film has high water holding ability;
controls gas exchanges; inhibits solute transport,
organic vapour transfers, as well as oil and fat
migration; improves mechanical properties of food
to simplify handling and carriage; has neutral sensory
characteristics, improving sensory properties of food
Table 2 Bioactive peptides derived from whey proteins
Name Peptide sequence Fragment Function
α-Lactorphin Tyr-Gly-Leu-Phe 50–53 Opioid agonist, ACE inhibition
β-Lactorphin Tyr-Leu-Leu-Phe 102–105 Non-opioid stimulatory effect on ileum,
10–105 ACE inhibition
β-Lactotensin His-Ile-Arg-Leu 146–149 Ileum contraction, opioid
Serophin Tyr-Gly-Phe-Gln-Asp-Ala 399–404 Opioid
Albutensin A Ala-Leu-Lys-Ala-Trp-Ser-Val-Ala-Arg 208–216 Ileum contraction, ACE inhibition
Lactoferricin Lys-Cys-Arg-Arg-Trp-Glu-Trp-Arg-Met-Lys0Leu-Gly-
Ala-Pro-Ser-Ile-Thr-Cys-Val-Arg-Arg-Ala-Phe
17–42 Antimicrobial
Glycomacro peptide
(GMP)
– 106–169 Food intake regulation
14
Dinika Isfari et al. Foods and Raw Materials, 2019, vol. 7, no. 2, pp. Х–Х
products [57]. Edible films should consist of components
produced mainly from edible biopolymers and food
grade additives. The additives should meet safety
requirements to food additives and to be at least GRAS
(Generally Recognized as Safe) [59].
There are two ways to create an edible film: wet
process and dry process. Wet process applies dispersion
in a solvent such as water, alcohol, or mixture of water
and alcohol, or other solvents. The film-forming solution
is then casted and dried to obtain films. The dry process
does not require any solvent. It can be produced by
compression, molding, or extrusion [60, 61]. The
film-making and coating processes include melting
and solidification of solid fats, waxes, and resins;
conservation of hydrocolloid; complex conservation of
two hydrocolloids; and thermal gelation or coagulation
by heating [57]. Therefore, the dry process usually needs
more equipment, which results in higher cost compared
to the wet process.
In edible film production, the incorporation of a
certain additive is possible to form an advanced system
called active packaging [62]. The additive compound
enhances shelf-life and stability of the product, as well
as improves its microbiological safety and sensory
attributes [63]. The following additives can be used in
edible films: flavouring agents, spices, antimicrobial
substances, antioxidants, pigments, light absorbers,
salts, etc. Antioxidants and antimicrobial additives
are commonly used in order to prevent spoilage and
thus enhance safety. Antimicrobial agents, being
used in active packaging, can overcome the hurdles
of uncontrolled migration and interaction of an active
compound of various natural antioxidants used directly
in food [64, 65].
Comparison of characteristics from various film
bases. Edible film or even active packaging usually
use polysaccharide, protein, lipid, or composite base to
make a film forming solution. Thus, fermented whey can
be one of multifunctional ingredients and act as a filmforming
base and an antimicrobial agent.
Researchers have focused on the use of composite
based films to explore the complement advantages
of each component [64, 66]. A composite based film
can be both one-layer and multiple-layer. The matrix
of hydrophilic and hydrophobic lipid, which is called
bi-layer composite system, has better functional
characteristics than pure hydrocolloid films. However,
one of disadvantages of bi-layers composite systems is
longer preparation process. It requires two casting and
two drying stages, which has made these laminated films
less popular in food industry [67]. In order to enhance
holding properties of active packaging, scientists have
studied its mechanical properties (table 3). These are
transparency, oxygen permeability, carbon dioxide
permeability, water vapor permeability, emulsion
stability, and glass transition temperature.
Generally, lipid films have the less structural
integrity compared to protein or polysaccharide
films [68]. The use of lipids in edible films has resulted
in heterogenous film structure that has an impact on
discontinuities in the polymer and production of a
strong emulsion matrix [69]. A composite film based on
polysaccharide has the greatest mechanical properties,
which allows its using in gastronomy. Along with
protein added, polysaccharide film is an optimal active
packaging.
Besides the film based component, the composition
of the edible film is also an important factor. Plasticizer
is one of substantial components to create a flexible film
by reducing interaction between intermolecular starch
[70]. Examples of plasticizer are polyol groups such as
glycerol, xylitol, sorbitol, mannitol, and sucrose [18,
70]. Xanthan gum and carrageenan are also promising
plasticizers which provide the product with strength
and durability with great sensory properties. They
demonstrate high stabilizing ability and resistance
to water, [71]. The plasticizer is able to reduce
intermolecular bonds between amylose, amylopectin, and
amylose-amylopectin in the starch matrix and replace
them with hydrogen bonds between plasticizer and
starch. This reduces brittle and enhances flexibility [68].
Table 3 Edible film characteristics
Characteristic Effective components
for base making
Ineffective components
for base making
Additional info Source
Mechanical
properties
Flexibility and texture of
film
Composite, pure
hydrocolloid matrix
Lipid (good in coating,
bad in film)
[72]
Transparency Lightness and colourless
of film
Emulsified films with
lipid
– The higher lipid content,
the less lightness
[73]
Oxygen
permeability
O2 transfer through film Hydrocolloid, protein Hydrophobic [74]
[75]
Carbon dioxide
permeability
CO2 transfer through film Cellulose films,
protein
Lipid (stearic acid
and palmitic)
The higher lipid content,
the weaker barrier
[76]
Water vapour
permeability
(WVP)
Moisture transfer through
film
Hydrophobic (lipid) Polysaccharide, Protein Better at smaller and
more homo-genous lipid
distributed
[77]
[78]
[79]
Water solubility
(WS)
Lower WS needed to protect
food from moisture loss
Lipid – Lipids reduce WS [80]
15
Dinika Isfari et al. Foods and Raw Materials, 2019, vol. 7, no. 2, pp. Х–Х
Table 4 Characteristics of composite film bases
Base Added component Method of making Thickness,
mm
WVP,
g/m·s·Pa
Water solubility,
%
Tensile strength,
MPa
Elongation
at break, %
Source
Native wheat starch,
whey protein isolate
Glycerol Dissolving (separately), heating at shaking
(separately, 85°C, 30 min), cooling, mixing,
drying (25°C, RH 40%, 24 h), peeling, storing
(RH 53%, 25°C, 7 days).
0.109 ± 0.008 7.95 ± 0.33
(RH 30–100%)
10.53 ± 3.80 4.67 ± 0.19 76.26 ± 8.92 [84]
Soya protein
(defatted), papaya
puree (pectin)
Starch, glycerol, gelatin Papaya puree film production (mixing
PP + 0,07 ± 0,005 water + starch, dissolved at
75°C, 30 min), mixing & stirring (separately,
30 min each), mixing, casting, drying (40°C,
RH 23%, 18 h), peeling, storing 48 h
0.119 ± 0.002 5.55 ± 0.43
(g·mm/
m2·h·kPa)
82.26 ± 0.27 6.80 ± 0.08 22.23 ± 0.06 [85]
Almond oils, whey
protein isolate
Glycerol Dissolving WPI (250 rpm, 80°C, 30 min),
cooling, mixing (13500 rpm, 5 min), casting,
drying (25°C, RH 50%, 24 h), peeling, storing
(RH 53%, 25°C, 48 h)
0.07 ± 0.005 11.00 ± 1.60 46.90 ± 0.69 5.40 ± 0.80 53.70 ± 7.7 [86]
Soya protein, acetem
(hydrogenated
soybean oil)
Vegetable glycerin, tween 60
(polyoxyethylene sorbitan
monostearate) as a surfactant
Emulsification (mixing, 300 rpm, 25°C,
30 min), mixing (1 h), heating (90°C,
45 min), mixing (1300 rpm, 2 h),
degassing, casting, drying (15 h, 24°C)
0.113 ± 0.008 2.70 ± 0.46
(g·mm/
m2·h·kPa)
– 2.15 ± 0.18 342.4 ± 25.2 [87]
The flexibility of the film depends on the
concentration of the plasticizer in fthe ilm-forming
solution.High or low concentrations would result in antiplasticization.
For example, glycerol in the amount of
over 30% used in the starch-based film is the case. It will
result in a decrease in such characteristics as elongation
at break. It was established that strong interaction
between plasticizer and other molecules blocked the
macromolecular mobility [70, 81]. On the other hand, if
the plasticizer concentration is too low, the film formed
will be brittle and hard to handle. Generally, the optimal
concentration of plasticizer is 20–45% [82].
The potential of fermented whey for active
packaging composite. The composite of edible film
can be made to complement each single material-based
film characteristics. Protein is usually used as one of
material-based because of its nutritional value [83]. The
comparison of the composite edible film using proteinbased
is shown in Table 4. From all of the sources of
protein, soya and whey have been mostly used.
As a food barrier capability, the addition of oil
has resulted in a lower WVP, which is showed in a
comparison of soya protein with oil and with pectin.
Thereby, we can conclude that a composite protein film
with oil has better barrier properties. However, the water
solubility of whey protein with starch is higher than
that of soya protein with pectin. In terms of mechanical
properties, whey protein with starch provides a better
result than soy protein with pectin. However, some
other parameters cannot be compared because of the
difference between the film production and the analysis
method. Based on the description above, it is possible
to conclude that the whey protein is more effective than
soya protein to produce the edible film.
Functional characteristics of fermented whey
make it promising raw material for active packaging.
Bioactive peptides from fermented whey have had
their ability to act as an antimicrobial agent; immunomodulatory
peptides regulate cell-mediated and
humoral immune functions; ACE inhibitory peptides
lower blood pressure; and opioid peptides are effective
against hypotension, lack of appetite, etc., as well as
exhibit antioxidant properties, protecting cells from free
radicals [31].
Several bioactive peptides derived from whey
protein are also known for its capability to enhance the
defence towards various pathogenic bacteria and yeast.
Their antimicrobial activity can inhibit the growth of
such microorganisms effectively. The incorporation
of bioactive peptides into film is more effective way to
lower the concentration of microorganisms than direct
using them in food. Thus, it allow avoiding unwanted
flavours and odor of food [88].
In terms of the characteristics, a good characteristic
can be achieved if the protein contained in the cheese
whey is mixed with starch that contained polysaccharides.
With the addition of plasticizer, this composite based
film will have good mechanical properties as well as the
barrier ability to prolong food shelf-life.
16
Dinika Isfari et al. Foods and Raw Materials, 2019, vol. 7, no. 2, pp. Х–Х
Advanced process to create composite fermented
cheese whey film. Nowadays, an advanced process
to create an edible composite is based film-forming
solution. The film with cellulose, whey and sunflower
oil based are stirred with Ultraturrax homogenizer at
11000 rpm for 3 min to decrease the droplet sizes of
oil. As a result, the smaller droplet sizes can disperse
uniformly in the hydrocolloid matrix. Therefore,
the penetration of water into film will be harder,
which will result in better water vapour transfer.
The combination of the degassed method under
vacuum (80 kPa) and a vacuum pump for 5 min
will result in the film production with tensile
strength of 8.59 MPa, elongation at break 35.94%,
WVP 3.211 g/m·s·Pa, and transparency of 3,637 % [79].
There are several methods available to increase
the stability and the quality of characteristics of active
packaging. The addition of enzyme is one of methods
to enhance the film quality in the complex edible film.
The presence of Transglutaminase (TGase) has caused
enzymatic cross-linking in P/P soluble electrostatic
aggregates. Thus, TGase can strongly produce
composite bioplastics by escalating the mechanical and
barrier characteristics. Supramolecular structure of P/P
complex as enzyme substrate is crucially influencing
pH of a film-forming solution. With the addition of
TGase, film characteristics at pH (pH complexation
around 3.25–5.5, when soluble P/P complexes occur)
create better characteristics than higher pH. The pH can
significantly increase tensile strength and elongation at
break, and reduce Young’s modulus and WVP [89].
For the usage of fermented cheese whey in the
active packaging, there is an advanced process that
can be added in the fermentation process. Candida
sp. is one of the yeast that has already found in Serro
Minas, a cheese from Brazil [90]. Recently, a study
for identifying the indigenous yeast that contained
in homemade mozzarella whey has also found that
Candida sp. contained in mozzarella whey and Greek
fermented whey [91]. It means that Candida sp. is
naturally contained in cheese whey and can live to
ferment the whey [92]. Candida spp. is also known
as the most massive yeasts to produce xylitol with
63–70% w/w yields. According to several studies,
C. tropicalis mutant maximises the xylitol production,
reaching 100% yields [93]. It is known that xylitol
is one of sugar alcohol that can be utilized in the film
production as a plasticizer [18]. Fermented cheese whey
can act as an antimicrobial agent and natural plasticizer.
Prospects of the use of edible films and active
packaging with cheese whey. The edible film can be
an effective solution to reduce plastic waste of food
packaging. Addition of several antimicrobials can
also be used to prolong the shelf life to reach a proper
packaging system which is similar to the plastic
packaging. Thus, fermented cheese whey as a base
ingredient of composite film system is able to meet this
requirement. Despite some disadvantages of protein, its
combination with other ingredients make is possible to
obtain an excellent film with required characteristics.
Besides various modification of film manufacture,
the cost in creating edible film must be taken into
account. The edible film should be cost-effective
compared to plastic, paper, or any other packaging that
can harm the environment. Thus, advancing the edible
film production is important to make film characteristics
as high as characteristics of plastic packaging.
The simplified process of cheese whey fermentation
using indigenous yeast can also increase the
antimicrobial properties of the fermented cheese whey.
In the future, advancing film manufacture process from
fermented cheese whey can be one of massive ways to
create modern environmentally-friendly packaging.
CONCLUSION
Cheese whey, a by-product of cheese-making
process, has several functional effects, including
inedible film formation. Bioactive peptides contained
in native cheese whey can be enhanced by fermentation
to generate high antimicrobial activity. In addition, a
composite edible film can be produced from fermented
whey and starch to gain good mechanical characteristics
as well as a good barrier to prolong food shelf-life. The
utilisation of fermented cheese whey as an edible film
material allows obtaining an active packaging system
with high antimicrobial activity.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
ACKNOWLEDGEMENT
Authors thank the Ministry of Research, Technology
and Higher Education of The Republic of Indonesia that
funded the research through ‘Penelitian Tesis Magister’,
2019. This article’s publication is supported by the
United States Agency for International Development
(USAID) through the Sustainable Higher Education
Research Alliance (SHERA) Program for Universitas
Indonesia’s Scientific Modeling, Application, Research,
and Training for City-centered Innovation and
Technology (SMART CITY) Project, Grant #AID-
497-A-1600004, Sub Grant #IIE-00000078-UI-1.

1. Utama GL, Kurnani TBA, Sunardic, Balia RL. Reducing cheese-making by-product disposal through ethanol fermentation and the utilization of distillery waste for fertilizer. International Journal of GEOMATE. 2017;13(37):103-107. DOI: https://doi.org/10.21660/2017.37.2737.

2. Božanic R, Barukcic I, Jakopovic LK, Tratnik L. Possibilities of Whey Utilisation. Austin Journal of Nutrition and Food Sciences. 2014;2(7):1036-1042.

3. Jelen P. Whey Processing. Utilization and Products. In: Roginski H, editor. Encyclopedia of Dairy Science. Academic Press; 2002. pp. 2739-2745. DOI: https://doi.org/10.1016/B0-12-227235-8/00511-3.

4. Smithers GW. Whey and whey proteins-From ‘gutter-to-gold’. International Dairy Journal. 2008;18(7):695-704. DOI: https://doi.org/10.1016/j.idairyj.2008.03.008.

5. Tunick MH. Whey Protein Production and Utilization: A Brief History. In: Onwulata CI, Huth PJ, editors. Whey Processing, Functionality and Health Benefits. John Wiley & Sons; 2009. pp. 1-13. DOI: https://doi.org/10.1002/9780813803845.ch1.

6. Andrade RP, Melo CN, Genisheva Z, Schwan RF, Duarte WF. Yeasts from Canastra cheese production process: Isolation and evaluation of their potential for cheese whey fermentation. Food Research International. 2017;91:72-79. DOI: https://doi.org/10.1016/j.foodres.2016.11.032.

7. Maruddin F, Malaka R, Hajrawati, Taufik M. Antibacterial Activity of Fermented Whey Beverage by Products from Buffalo Dangke. Materials of the Buffalo International Conference 2013; 2013; Makassar. Makassar: University of Hasanuddin; 2013. p. 329-334.

8. Balia RL, Fleet GH. Growth of Yeasts Isolated from Cheeses on Organic Acids in the Presence of Sodium Chloride. Food Technology and Biotechnology. 1999;37(2):73-79.

9. Caric M. Technology and Milk Products, Dried and Concentrated. Beograd: Naucna knjiga;1990.

10. Tratnik L. The role of whey in functional dairy food production. Mljekarstvo: journal for dairy production and processing improvement. 2003;53(4):325-352.

11. Guimarães PMR, Teixeira JA, Domingues L. Fermentation of lactose to bio-ethanol by yeasts as part of integrated solutions for the valorisation of cheese whey. Biotechnology Advances. 2010;28(3):375-384. DOI: https://doi.org/10.1016/j.biotechadv.2010.02.002.

12. González Siso MI. The biotechnological utilization of cheese whey: A review. Bioresource Technology. 1996;57(1):1-11. DOI: https://doi.org/10.1016/0960-8524(96)00036-3.

13. Pesta G, Meyer-Pittroff R, Russ W. Ulitization of Whey. In: Oreopoulou V, Russ W, editors. Utilization of By-Products and Treatment of Waste in the Food Industry. Boston Springer; 2007. pp. 193-207. DOI: https://doi.org/10.1007/978-0-387-35766-9_10.

14. Hayes M, Ross RP, Fitzgerald GF, Hill C, Stanton C. Casein-derived antimicrobial peptides generated by Lactobacillus acidophilus DPC6026. Applied and Environmental Microbiology. 2006;72(3):2260-2264. DOI: https://doi.org/10.1128/AEM.72.3.2260-2264.2006.

15. Clare DA, Swaisgood HE. Bioactive milk peptides: A prospectus. Journal of Dairy Science. 2000;83(6):1187-1195. DOI: https://doi.org/10.3168/jds.S0022-0302(00)74983-6.

16. Sánchez-Ortega I, García-Almendárez BE, Santos-López EM, Amaro-Reyes A, Barboza-Corona JE, Regalado C. Antimicrobial Edible Films and Coatings for Meat and Meat Products Preservation. Scientific World Journal. 2014;2014. DOI: https://doi.org/10.1155/2014/248935.

17. Zerihun M, Worku T, Sakkalkar SR. Development and Characterization of Antimicrobial Packaging Films. Journal of Ready to Eat Food. 2016;3(2):13-24.

18. Akhtar J, Omre PK, Ahmad Azad ZRA. Edible Coating for Preservation of Perishable Foods: A Review. Journal of Ready to Eat Food. 2015;2(3):81-88.

19. Jambeck JR, Geyer R, Wilcox C, Siegler TR, Perryman M, Andrady A, et al. Plastic waste inputs from land into the ocean. Science. 2015;347(6223):768-771. DOI: https://doi.org/10.1126/science.1260352.

20. Godfray HCJ, Beddington JR, Crute IR, Haddad L, Lawrence, Muir JF, et al. Food security: the challenge of feeding 9 billion people. Science. 2010;327(5967):812-818. DOI: https://doi.org/10.1126/science.1185383.

21. Lamont WJ. Plastics: Modifying the microclimate for the production of vegetable crops. HortTechnology. 2005;15(3):477-481.

22. Krueger MC, Harms H, Schlosser D. Prospects for microbiological solutions to environmental pollution with plastics. Applied Microbiology and Biotechnology. 2015;99(21):8857-8874. DOI: https://doi.org/10.1007/s00253-015-6879-4.

23. Restrepo-Flórez J-M, Bassi A, Thompson MR. Microbial degradation and deterioration of polyethylene - A review. International Biodeterioration and Biodegradation. 2014;88:83-90. DOI: https://doi.org/10.1016/j.ibiod.2013.12.014.

24. Steinmetz Z, Wollmann C, Schaefer M, Buchmann C, David J, Tröger J, et al. Plastic mulching in agriculture. Trading short-term agronomic benefits for long-term soil degradation? Science of the Total Environment. 2016;550:690-705. DOI: https://doi.org/10.1016/j.scitotenv.2016.01.153.

25. Kitts DD, Weiler K. Bioactive proteins and peptides from food sources. Applications of bioprocesses used in isolation and recovery. Current Pharmaceutical Design. 2003;9(16):1309-1323. DOI: https://doi.org/10.2174/1381612033454883.

26. Cladera-Olivera F, Caron GR, Brandelli A. Bacteriocin-like substance production by Bacillus licheniformis strain P40. Letters in Applied Microbiology. 2004;38(4):251-256. DOI: https://doi.org/10.1111/j.1472-765X.2004.01478.x.

27. Klaenhammer TR. Bacteriocins of lactic acid bacteria. Biochimie. 1988;70(3):337-349. DOI: https://doi.org/10.1016/0300-9084(88)90206-4.

28. De Vuyst L. Nutritional factors affecting nisin production by Lactococcus lactis subsp. actis NIZO 22186 in a synthetic medium. Journal of Applied Bacteriology. 1995;78(1):28-33. DOI: https://doi.org/10.1111/j.1365-2672.1995. tb01669.x.

29. Vignolo GM, de Kairuz MN, de Ruiz Holgado AAP, Oliver G. Influence of growth conditions on the production of lactocin 705, a bacteriocin produced by Lactobacillus casei CRL 705. Journal of Applied Bacteriology. 1995;78(1):5-10. DOI: https://doi.org/10.1111/j.1365-2672.1995.tb01665.x.

30. Krier F, Revol-Junelles AM, Germain P. Influence of temperature and pH on production of two bacteriocins by Leuconostoc mesenteroides subsp. mesenteroides FR52 during batch fermentation. Applied Microbiology and Biotechnology. 1998;50(3):359-363. DOI: https://doi.org/10.1007/s002530051304.

31. Mohanty DP, Mohapatra S, Misra S, Sahu PS. Milk derived bioactive peptides and their impact on human health - A review. Saudi Journal of Biological Sciences. 2016;23(5):577-583. DOI: https://doi.org/10.1016/j.sjbs.2015.06.005,

32. Madureira AR, Pereira CI, Gomes AMP, Pintado ME, Xavier Malcata F. Bovine whey proteins - Overview on their main biological properties. Food Research International. 2007;40(10):1197-1211. DOI: https://doi.org/10.1016/j.foodres.2007.07.005.

33. Mohanty D, Jena R, Choudhury PK, Pattnaik R, Mohapatra S, Saini MR. Milk Derived Antimicrobial Bioactive Peptides: A Review. International Journal of Food Properties. 2016;19(4):837-846. DOI: https://doi.org/10.1080/10942912.2015.1048356.

34. Ibrahim HR, Matsuzaki T, Aoki T. Genetic evidence that antibacterial activity of lysozyme is independent of itscatalytic function. FEBS Letters. 2001;506(1):27-32. DOI: https://doi.org/10.1016/S0014-5793(01)02872-1.

35. Vorland LH, Ulvatne H, Rekdal O, Svendsen JS. Initial binding sites of antimicrobial peptides in Staphylococcus aureus and Escherichia coli. Scandinavian Journal of Infectious Diseases. 1999;31(5):467-473. DOI: https://doi.org/10.1080/00365549950163987.

36. Recio I, Visser S. Two ion-exchange chromatographic methods for the isolation of antibacterial peptides from lactoferrin: In situ enzymatic hydrolysis on an ion-exchange membrane. Journal of Chromatography A. 1999;831(2):191-201. DOI: https://doi.org/10.1016/S0021-9673(98)00950-9.

37. Hoek KS, Milne JM, Grieve PA, Dionysius DA, Smith R. Antibacterial activity in bovine lactoferrin-derived peptides. Antimicrobial Agents and Chemotherapy. 1997;41(1):54-59.

38. Van Der Kraan MIA, Groenink J, Nazmi K, Veerman ECI, Bolscher JGM, Nieuw Amerongen AV. Lactoferrampin: a novel antimicrobial peptide in the N1-domain of bovine lactoferrin. Peptides. 2004;25(2):177-183. DOI: https://doi.org/10.1016/j.peptides.2003.12.006.

39. Korhonen H, Pihlanto A. Technological options for the production of health-promoting proteins and peptides derived from milk and colostrum. Current Pharmaceutical Design. 2007;13(8):829-843. DOI: https://doi.org/10.2174/138161207780363112.

40. Molina PE, Abumrad NN. Metabolic effects of opiates and opioid peptides. Advances in Neuroimmunology. 1994;4(2):105-116. DOI: https://doi.org/10.1016/S0960-5428(05)80005-1.

41. Dziuba J, Minkiewicz P, Nałȩcz D, Iwaniak A. Database of biologically active peptide sequences. Nahrung - Food.1999;43(3):190-195. DOI: https://doi.org/10.1002/(SICI)1521-3803(19990601)43:3<190::AIDFOOD190> 3.0.CO;2-A.

42. Abuja PM, Albertini R. Methods for monitoring oxidative stress, lipid peroxidation and oxidation resistance of lipoproteins. Clinica Chimica Acta. 2001;306(1-2):1-17. DOI: https://doi.org/10.1016/S0009-8981(01)00393-X.

43. Korhonen H, Pihlanto A. Food-derived bioactive peptides - opportunities for designing future foods. Current Pharmaceutical Design. 2003;9(16):1297-1308. DOI: https://doi.org/10.2174/1381612033454892.

44. Vermeirssen V, Van Camp J, Verstraete W. Bioavailability of angiotensin I converting enzyme inhibitory peptides. British Journal of Nutrition. 2004;92(3):357-366. DOI: https://doi.org/10.1079/BJN20041189.

45. Mohanty DP, Tripathy P, Mohapatra S, Samantaray DP. Bioactive potential assessment of antibacterial peptide produced by Lactobacillus isolated from milk and milk products. International Journal of Current Microbiology and Applied Sciences. 2014;3(6):72-80.

46. Suetsuna K, Ukeda H, Ochi H. Isolation and characterization of free radical scavenging activities peptides derived from casein. Journal of Nutritional Biochemistry. 2000;11(3):128-131. DOI: https://doi.org/10.1016/S0955-2863(99)00083-2.

47. Rival SG, Boeriu CG, Wichers HJ. Caseins and Casein Hydrolysates. Antioxidative Properties Peroral Calcium Dosage of Infants. Acta Medica Scandinavica. 2001;55:247-255.

48. Gauthier SF, Pouliot Y, Maubois J-L. Growth factors from bovine milk and colostrum: composition, extraction and biological activities. Lait. 2006;86(2):99-125. DOI: https://doi.org/10.1051/lait:2005048.

49. Pihlanto-Leppälä A, Koskinen P, Paakkari I, Tupasela T, Korhonen HJT. Opioid whey protein peptides obtained by membrane filtration. IDF Bulletin. 1996;311:36-38.

50. Shah NP. Effects of milk-derived bioactives: An overview. British Journal of Nutrition. 2000;84:S3-S10.

51. Korhonen H, Pihlanto-Leppälä A, Rantamäki P, Tupasela T. The functional and biological properties of whey proteins: prospects for the development of functional foods. Agricultural and Food Science in Finland. 1998;7(2):283-296.

52. Park YW, Nam MS. Bioactive Peptides in Milk and Dairy Products: A Review. Korean Journal for Food Science of Animal Resources. 2015;35(6):831-840. DOI: https://doi.org/10.5851/kosfa.2015.35.6.831.

53. Lucarini M. Bioactive Peptides in Milk: From Encrypted Sequences to Nutraceutical Aspects. Beverages. 2017;3(3):41-50. DOI: https://doi.org/10.3390/beverages3030041.

54. Beucher S, Levenez F, Yvon M, Corring T. Effect of caseinomacropeptide (CMP) on cholecystokinin (CCK) release in rat. Reproduction Nutrition Development. 1994;34(6):613-614. DOI: https://doi.org/10.1051/rnd:19940611.

55. Neelima, Sharma R, Rajput YS, Mann B. Chemical and functional properties of glycomacropeptide (GMP) and its role in the detection of cheese whey adulteration in milk: A review. Dairy Science and Technology. 2013;93(1):21-43. DOI: https://doi.org/10.1007/s13594-012-0095-0.

56. Kumari S, Vij S. Effect of Bioactive Peptides Derived from Fermented Whey Based Drink Against Food Borne Pathogens. International Journal of Current Microbiology and Applied Science. 2015;4(3):936-941.

57. Umaraw P, Verma AK. Comprehensive review on application of edible film on meat and meat products: An ecofriendly approach. Critical Reviews in Food Science and Nutrition. 2017;57(6):1270-1279. DOI: https://doi.org/10.1080/10408398.2014.986563.

58. Municipal Solid Waste in the United States: 2005 Facts and Figures Executive Summary. United States Environmental Protection Agency. 2006. 165 p.

59. Sothornvit R, Krochta JM. Water Vapor Permeability and Solubility of Films from Hydrolyzed Whey Protein. Journal of Food Science. 2000;65(4):700-705.

60. Pommet MA, Redl A, Guilbert S, Morel MH. Intrinsic influence of various plasticizers on functional properties and reactivity of wheat gluten thermoplastic materials. Journal of Cereal Science. 2005;42(1):81-91. DOI: https://doi.org/10.1016/j.jcs.2005.02.005.

61. Liu L, Kerry JF, Kerry JP. Effect of food ingredients and selected lipids on the physical properties of extruded edible films/casings. International Journal of Food Science and Technology. 2006;41(3):295-302. DOI: https://doi.org/10.1111/j.1365-2621.2005.01063.x.

62. Day BPF. Active Packaging. In: Coles R, McDowell D, Kirwan MJ, editors. Food Packaging Technology. Boca Raton: CRC Press; 2003. pp. 282-302.

63. Khalil MS, Ahmed ZS, Elnawawy AS. Evaluation of the Physicochemical Properties and Antimicrobial Activities of Bioactive Biodegradable Films. Jordan Journal of Biological Sciences. 2013;6(1):51-60. DOI: https://doi.org/10.12816/0000259.

64. Kuswandi B, Wicaksono Y, Jayus, Abdullah A, Heng LY, Ahmad M. Smart packaging: Sensors for monitoring of food quality and safety. Sensing and Instrumentation for Food Quality and Safety. 2011;5(3-4):137-146. DOI: https://doi.org/10.1007/s11694-011-9120-x.

65. Morsy MK, Khalaf HH, Sharoba AM, El-Tanahi HH, Cutter CN. Incorporation of Essential Oils and Nanoparticles in Pullulan Films to Control Foodborne Pathogens on Meat and Poultry Products. Journal of Food Science. 2014;79(4):M675-M684. DOI: https://doi.org/10.1111/1750-3841.12400.

66. Debeaufort F, Quezada-Gallo J-A, Voilley A. Edible films and coatings: Tomorrow’s packagings: A review. Critical Reviews in Food Science and Nutrition. 1998;38(4):299-313. DOI: https://doi.org/10.1080/10408699891274219.

67. Galus S, Kadzińska J. Food applications of emulsion-based edible films and coatings. Trends in Food Science and Technology. 2015;45(2):273-283. DOI: https://doi.org/10.1016/j.tifs.2015.07.011.

68. Gontard N, Marchesseau S, Cuq J-L, Guilbert S. Water vapour permeability of edible bilayer films of wheat gluten and lipids. International Journal of Food Science & Technology. 1995;30(1):49-56. DOI: https://doi.org/10.1111/j.1365-2621.1995.tb01945.x.

69. Fabra MJ, Talens P, Chiralt A. Tensile properties and water vapor permeability of sodium caseinate films containing oleic acid-beeswax mixtures. Journal of Food Engineering. 2008;85(3):393-400. DOI: https://doi.org/10.1016/j.jfoodeng.2007.07.022.

70. Sanyang ML, Sapuan SM, Jawaid M, Ishak MR, Sahari J. Effect of Plasticizer Type and Concentration on Tensile, Thermal and Barrier Properties of Biodegradable Films Based on Sugar Palm (Arenga pinnata) Starch. Polymers. 2015;7(6):1106-1124. DOI: https://doi.org/10.3390/polym7061106.

71. Bykov DE, Eremeeva NB, Makarova NV, Bakharev VV, Demidova AV, Bykova TO. Influence of Plasticizer Content on Organoleptic, Physico-Chemical and Strength Characteristics of Apple Sauce-Based Edible Film. Foods and Raw Materials. 2017;5(2):5-14. DOI: https://doi.org/10.21603/2308-4057-2017-2-5-14.

72. Hopkins EJ, Chang C, Lam RSH, Nickerson MT. Effects of flaxseed oil concentration on the performance of a soy protein isolate-based emulsion-type film. Food Research International. 2015;67(1):418-425. DOI: https://doi.org/10.1016/j.foodres.2014.11.040.

73. Ortega-Toro R, Jiménez A, Talens P, Chiralt A. Effect of the incorporation of surfactants on the physical properties of corn starch films. Food Hydrocolloids. 2014;38:66-75. DOI: https://doi.org/10.1016/j.foodhyd.2013.11.011.

74. Hambleton A, Debeaufort F, Bonnotte A, Voilley A. Influence of alginate emulsion-based films structure on its barrier properties and on the protection of microencapsulated aroma compound. Food Hydrocolloids. 2009;23(8):2116-2124. DOI: https://doi.org/10.1016/j.foodhyd.2009.04.001.

75. Navarro-Tarazaga ML, Massa A, Pérez-Gago MB. Effect of beeswax content on hydroxypropyl methylcellulose-based edible film properties and postharvest quality of coated plums (Cv. Angeleno). LWT - Food Science and Technology. 2011;44(10):2328-2334. DOI: https://doi.org/10.1016/j.lwt.2011.03.011.

76. Ayranci E, Tunc S. The effect of fatty acid content on water vapour and carbon dioxide transmissions of cellulosebased edible films. Food Chemistry. 2001;72(2):231-236. DOI: https://doi.org/10.1016/S0308-8146(00)00227-2.

77. Bourtoom T. Edible protein films: Properties enhancement. International Food Research Journal. 2009;16(1).

78. Pérez-Gago MB, Krochta JM. Lipid particle size effect on water vapor permeability and mechanical properties of whey protein/beeswax emulsion films. Journal of Agricultural and Food Chemistry. 2001;49(2):996-1002. DOI: https://doi.org/10.1021/jf000615f.

79. Rubilar JF, Zúñiga RN, Osorio F, Pedreschi F. Physical properties of emulsion-based hydroxypropyl methylcellulose/whey protein isolate (HPMC/WPI) edible films. Carbohydrate Polymers. 2015;123:27-38. DOI: https://doi.org/10.1016/j.carbpol.2015.01.010.

80. Zahedi Y, Ghanbarzadeh B, Sedaghat N. Physical properties of edible emulsified films based on pistachio globulin protein and fatty acids. Journal of Food Engineering. 2010;100(1):102-108. DOI: https://doi.org/10.1016/j.jfoodeng.2010.03.033.

81. Sahari J, Sapuan SM, Ismarrubie ZN, Rahman MZA. Physical and chemical properties of different morphological parts of sugar palm fibres. Fibres and Textiles in Eastern Europe. 2012;91(2):21-24.

82. Laohakunjit N, Noomhorm A. Effect of Plasticizers on Mechanical and Barrier Properties of Rice Starch Film. Starch/Staerke. 2004;56(8):348-356. DOI: https://doi.org/10.1002/star.200300249.

83. Cao N, Fu Y, He J. Preparation and physical properties of soy protein isolate and gelatin composite films. Food Hydrocolloids. 2007;21(7):1153-1162. DOI: https://doi.org/10.1016/j.foodhyd.2006.09.001.

84. Basiak E, Galus S, Lenart A. Characterisation of composite edible films based on wheat starch and whey-protein isolate. International Journal of Food Science and Technology. 2015;50(2):372-380. DOI: https://doi.org/10.1111/ijfs.12628.

85. Tulamandi S, Rangarajan V, Rizvi SSH, Singhal RS, Chattopadhyay SK, Saha NC. A biodegradable and edible packaging film based on papaya puree, gelatin, and defatted soy protein. Food Packaging and Shelf Life. 2016;10:60-71. DOI: https://doi.org/10.1016/j.fpsl.2016.10.007.

86. Galus S, Kadzińska J. Whey protein edible films modified with almond and walnut oils. Food Hydrocolloids.2016;52(1):78-86. DOI: https://doi.org/10.1016/j.foodhyd.2015.06.013.

87. Otoni CG, Avena-Bustillos RJ, Olsen CW, Bilbao-Sáinz C, McHugh TH. Mechanical and water barrier properties of isolated soy protein composite edible films as affected by carvacrol and cinnamaldehyde micro and nanoemulsions. Food Hydrocolloids. 2016;57:72-79. DOI: https://doi.org/10.1016/j.foodhyd.2016.01.012.

88. McClements DJ. Encapsulation, protection, and release of hydrophilic active components: potential and limitations of colloidal delivery systems. Advances in Colloid and Interface Science. 2015;219:27-53. DOI: https://doi.org/10.1016/j.cis.2015.02.002.

89. Di Pierro P, Rossi Marquez G, Mariniello L, Sorrentino A, Villalonga R, Porta R. Effect of Transglutaminase on the Mechanical and Barrier Properties of Whey Protein/Pectin Films Prepared at Complexation pH. Journal of Agricultural and Food Chemistry. 2013;61(19):4593-4598. DOI: https://doi.org/10.1021/jf400119q.

90. Cardoso VM, Borelli BM, Lara CA, Soares MA, Pataro C, Bodevan EC, et al. The influence of seasons and ripening time on yeast communities of a traditional Brazilian cheese. Food Research International. 2015;69:331-340. DOI: https://doi.org/10.1016/j.foodres.2014.12.040.

91. Utama GL, Kurnani TBA, Sunardi, Balia RL. The Isolation and Identification of Stress Tolerance Ethanol-fermenting Yeasts from Mozzarella Cheese Whey. International Journal on Advanced Science, Engineering and Information Technology. 2016;6(2):252-257. DOI: https://doi.org/10.18517/ijaseit.6.2.752.

92. Balia RL, Kurnani TBA, Utama GL. Selection of Mozzarella Cheese Whey Native Yeasts with Ethanol and Glucose Tolerance Ability. International Journal on Advanced Science, Engineering and Information Technology. 2018;8(4):1091-1097. DOI: https://doi.org/10.18517/ijaseit.8.4.5869.

93. Ko BS, Rhee CH, Kim JH. Enhancement of xylitol productivity and yield using a xylitol dehydrogenase genedisrupted mutant of Candida tropicalis under fully aerobic conditions. Biotechnology Letters. 2006;28(15):1159-1162. DOI: https://doi.org/10.1007/s10529-006-9068-9.