Heat Treatment Of Milk Research Articles

Combined effect of acidification temperature and different acids on microstructure and textural properties of heat and acid-induced milk gels

Heat and acid-induced milk gels, such as Indian Paneer cheese, can serve as a meat substitute in various cuisines due to their non-melting and cookable features. This study investigated the effects of acidification temperature (60, 70, 80, or 90 °C) and different acidifiers (citric, lactic, or hydrochloric acids) on the composition, texture, and microstructure of these gels. Across all acids, increasing the acidification temperature reduced the yield of gel due to lower moisture retention. However, the hardness, springiness, and cohesiveness of the gels increased with temperature, influenced by the rate of protein aggregation and calcium recovery. At high temperatures (e.g., 90 °C), gels prepared by citric acid exhibited greater hardness and cohesiveness, but lower springiness compared to those made with lactic or hydrochloric acid. This effect may be attributed to the formation of a more compact gel network, characterized by fewer pores, and lower water mobility.

High-pressure processing and heat treatment of Murrah buffalo milk: Comparative study on microbial changes during refrigerated storage

This study aims to evaluate the effect of high-pressure processing (HPP) (500 and 600 MPa for 3 min and 5 min) on the microbial changes of Murrah buffalo milk in comparison to heat treatment (72 °C for 15 s of holding time) during refrigerated storage of 28 days. The results indicated that the total plate count (TPC) of raw milk at day 0 was 5.5 ± 0.6 log10 CFU/mL. At day 0, heat treatment lowered TPC to 3.9 ± 0.6, while HPP treatment was in the range of 4.1 ± 0.3 to 4.8 ± 0.6 log10 CFU/mL. Similarly, lowered yeast and mold count and lactic acid bacteria were noted in heat- and HPP-treated milk samples compared to the control sample during refrigerated storage. There were no Staphylococcus aureus and Escherichia coli detected in heat and HPP-treated samples. Heat or HPP treatment at 600 MPa for 5 min significantly extended the shelf-life of Murrah buffalo milk for three weeks at the refrigerated storage. In addition, HPP treatment did not alter the pH, lightness (L* value), protein, or fat content of Murrah buffalo milk during refrigerated storage. Hence HPP at 600 MPa for 5 min could be a suitable alternative to conventional heat treatment.

Effect of protein polymorphisms on milk composition, coagulation properties, and protein profile in dairy sheep

The objective of this study was to quantify the effect of protein polymorphisms on milk composition, coagulation properties, and protein profile in dairy sheep from a New Zealand flock. A total of 470 test-day records, from 147 lactating ewes, were used in the statistical analyses. Protein polymorphisms observed in the RP-HPLC were self-named for purposes of the present study. Data were analyzed using a mixed linear model, including the fixed effects of ewe age, litter size, coat-colour, and stage of lactation, and, as a covariate, deviation from the median lambing date of the flock. The effects of protein polymorphisms were added to the model, one at a time. Protein polymorphisms were significantly (p < 0.05) associated with milk composition and protein profile. Polymorphisms of β-lactoglobulin were significantly associated with milk heat stability, being AB type more heat stable than AA. The other processability traits were not significantly affected by protein polymorphisms. Further studies are required to confirm the protein variants and the properties of individual protein polymorphisms.

Magnetization transfer MRI of intragastric milk digestion: A feasibility study in humans

Gastric milk protein coagulation has been extensively studied using in vitro and animal models. Yet, verifying these results in humans remains essential. In this study, we assessed the feasibility of using MT MRI for monitoring milk protein coagulation in vivo in humans. Twelve adults underwent MRI scans before and after ingesting 300 g of milk with low- or high-protein denaturation (LPD or HPD, respectively). We assessed coagulation and gastric emptying dynamics by deriving the MT ratio (MTR), total gastric content (TGC), semi-solid, and liquid volumes. The MTR values increased during digestion for both milk products, indicating an increase in the degree of coagulation. Prolonged heating of milk did not affect the MTR (MD = 16 %, 95 % CI [10–21], p = 0.15), but resulted in higher TGC volumes (MD 40.3 mL, 95 % CI [25.5–55.1], p = 0.044), indicating slower gastric emptying. We thus showed that by combining MT with conventional anatomical MRI both milk protein coagulation and gastric emptying dynamics, and thereby the impact of heating on gastric milk digestion, can be assessed in vivo in humans. Our work underpins the feasibility of using MRI as a non-invasive imaging tool for studying the effects of food processing and composition on gastric digestion.

Probing structural modification of milk proteins in the presence of pepsin and/or acid using small- and ultra-small-angle neutron scattering

Acid- and pepsin-induced milk protein coagulation plays a crucial role in the gastric digestion of milk. Real-time structural evolution at a nano- (e.g. colloidal calcium phosphate (CCP) and micelle) and micro- (gel network) level of unheated and heated (85 °C for 30 min) bovine milk was examined under acidic conditions and at low and high concentrations of pepsin using ultra-small- and small-angle neutron scattering (USANS and SANS), small-amplitude oscillatory rheometry and confocal scanning laser microscopy. Milk was treated with glucono-δ-lactone (GDL), pepsin or a combination of GDL and pepsin to induce coagulation. Heat-treated milk showed a faster increase in elastic storage modulus (G′) and scattering intensity (USANS and SANS) compared with unheated milk when coagulated with GDL or the combination of GDL and pepsin. At pH 6.3, heat treatment retarded pepsin (1.10 U/mL)-induced milk coagulation, with slower increases in G′ and scattering intensity. At a high concentration of pepsin (2000 U/mL) that mimics the concentration found in the stomach, general proteolysis followed coagulation. Heat treatment retarded coagulation but accelerated curd proteolysis. This study demonstrates how time-resolved USANS and SANS can be used to investigate the structural evolution of protein coagulation and degradation under gastric environment conditions at nano- and micro-metre length scales.

Микробиологические риски как причина пороков внешнего вида сыра

Aerobic Bacillus bacteria, yeasts, and micrococci are pigment-forming microorganisms responsible for color defects in cheese production. The article describes their environment, industry-related characteristics, types of defects they cause, and various color violations in commercial cheeses. The research featured domestic cheeses with yellow and red surface spots that appeared during industrial ripening and storage. Pigment-forming microorganisms developed on cheese surface at a low ripening temperature, high concentration of table salt, and critically low oxygen. Pigment-forming microflora proved to enter cheese from milk, brine, or production environment, e.g., water, air, and processing equipment, dry and succulent feeds being the main source of milk contamination with spore-forming aerobic bacteria, yeast, mold fungi, etc. Contamination of raw milk, milking equipment, and air environment with micrococci was primarily associated with cows’ udder and skin. Cheese production presupposes low-temperature heat treatment of raw milk, which means possible residual microflora in pasteurized milk. As a result, the total count of mesophilic aerobic and optionally anaerobic microorganisms, i.e., the potential pigment formers, was to stay below 104 CFU/cm3. Yeast and spore-forming Bacillus microorganisms demonstrated the acceptable level of ≤102 CFU/cm3 in milk intended for cheesemaking. If their total count exceeded 103 CFU/cm3, it indicated high microbiological risks of cheese appearance defects. The microflora responsible for discoloration of cheese surface was represented by yeast, micrococci, aerobic spores, or their combinations.

The Impact of Thermal Treatment Intensity on Proteins, Fatty Acids, Macro/Micro-Nutrients, Flavor, and Heating Markers of Milk-A Comprehensive Review.

Milk thermal treatment, such as pasteurization, high-temperature short-time processing, and the emerging ultra-short-time processing (<0.5 s), are crucial for ensuring milk safety and extending its shelf life. Milk is a nutritive food matrix with various macro/micro-nutrients and other constituents that are possibly affected by thermal treatment for reasons associated with processing strength. Therefore, understanding the relationship between heating strength and milk quality is vital for the dairy industry. This review summarizes the impact of thermal treatment strength on milk's nutritional and sensory properties, the synthesizing of the structural integrity and bioavailability of milk proteins, the profile and stability of fatty acids, the retention of macro/micro-nutrients, as well as the overall flavor profile. Additionally, it examines the formation of heat-induced markers, such as Maillard reaction products, lactulose, furosine, and alkaline phosphatase activity, which serve as indicators of heating intensity. Flavor and heating markers are commonly used to assess the quality of pasteurized milk. By examining former studies, we conclude that ultra-short-time-processing-treated milk is comparable to pasteurized milk in terms of specific parameters (such as whey protein behavior, furosine, and ALP contents). This review aims to better summarize how thermal treatments influence the milk matrix, guiding the dairy industry's development and balancing milk products' safety and nutritional value.

Application of solar thermal collectors for milk pasteurization to explore the potential of renewable energy in the dairy sector: Challenges and possibilities

Dairy farming has become a key business to fulfill the daily milk needs in populated countries like India. Conversely, pathogenic and spoilage microorganisms in raw milk are killed by applying different heat treatments to increase shelf life, preserve quality, and ensure safety. Among the heat treatment processes used at the dairy plant, pasteurization consumes a significant amount of heat, which increases the energy demand in the dairy sector. Since milk pasteurization occurs between 65°C and 150°C, multiple solar thermal collector alternatives are available for various kinds of pasteurization processes. Employing solar thermal collectors for milk pasteurization allows the dairy sector to use free solar energy. Solar energy in milk heat treatments minimizes fuel and power consumption, reducing carbon emissions and promoting sustainability. However, solar milk pasteurization in dairy sector is limited by the large area requirement, high initial cost, and weather dependency. There have been attempts to use different types of solar thermal collectors to pasteurize the milk in an effort to replace conventional energy usage with solar energy. The parameters of milk heat treatment, primarily pasteurization, have been discussed concerning energy usage. The benefits and limitations of various solar collectors for milk pasteurization and other heating applications in the dairy sector have been addressed. Multiple studies on integrating various solar thermal collectors with different pasteurization systems have been reviewed, summarized, and concluded.

Donor human milk treated by high-pressure processing improves the body growth of growth-restricted mice pups.

Pasteurized human donor milk (DM) is frequently used for feeding preterm newborns and extrauterine growth-restricted (EUGR) infants. Most human milk banks performed a pasteurization of DM using the standard method of Holder pasteurization (HoP) which consists of heating milk at 62.5°C for 30 min. High hydrostatic pressure (HHP) processing was proposed to be an innovative nonthermal method to pasteurize DM. However, the effect of different modes of DM pasteurization on body growth, intestinal maturation, and microbiota has never been investigated in vivo during the lactation. We aimed to study these effects in postnatally growth-restricted (PNGR) mice pups daily supplemented with HoP-DM or HHP-DM. PNGR was induced by increasing the number of pups per litter (15 pups/mother) at postnatal Day 4 (PND4). From PND8 to PND20, mice pups were supplemented with HoP-DM or HHP-DM. At PND21, the intestinal permeability was measured in vivo, the intestinal mucosal histology, gut microbiota, and short-chain fatty acids (SCFAs) level were analyzed. HHP-DM pups displayed a significantly higher body weight gain than HoP-DM pups during lactation. At PND21, these two types of human milk supplementations did not differentially alter intestinal morphology and permeability, the gene-expression level of several mucosal intestinal markers, gut microbiota, and the caecal SCFAs level. Our data suggest that HHP could be an attractive alternative to HoP and that HHP-DM may ensure a better body growth of preterm and/or EUGR infants.

Effects of Heat-Treated Lactobacillus helveticus CP790-Fermented Milk on Gastrointestinal Health in Healthy Adults: A Randomized Double-Blind Placebo-Controlled Trial.

Probiotic-fermented milk is commonly used to maintain intestinal health. However, the effects of heat-treated fermented milk, which does not contain live microorganisms, on intestinal function are not yet fully understood. This study aimed to investigate whether heat-treated Lactobacillus helveticus CP790-fermented milk affects fecal microbiota and gut health as a "postbiotic". A randomized, double-blind, placebo-controlled trial was conducted in healthy Japanese individuals aged 20-59 years with a tendency toward constipation. Participants consumed 100 mL of either the test beverage (n = 60) or placebo beverage (n = 60) for four weeks. The test beverages were prepared with heat-treated CP790-fermented milk, while the placebo beverages were prepared with nonfermented milk flavored with lactic acid. Fecal samples were analyzed using 16S rRNA gene sequencing. Constipation symptoms were assessed using defecation logs and the Patient Assessment of Constipation Symptoms (PAC-SYM) questionnaire. Mood state was also assessed using the Profile of Mood States 2 (POMS2) questionnaire to explore its potential as a "psychobiotic". Desulfobacterota were significantly decreased by CP790-fermented milk intake. PICRUSt2 analysis predicted a decrease in the proportion of genes involved in the sulfate reduction pathway following the consumption of CP790-fermented milk. The CP790-fermented milk intervention significantly improved stool consistency and straining during defecation. These improvements were correlated with a decrease in Desulfobacterota. After the intervention, overall mood, expressed as total mood disturbance, and depression-dejection were significantly better in the CP790 group than in the placebo group. These results suggest that the intake of CP790-fermented milk could be effective in modulating gut microbiota and improving constipation symptoms and mood states.

Discrimination of overheated pasteurized milk using mass spectrometry-based proteomics

Milk is one of the most widely consumed foods globally. To protect consumer interests, it is essential to establish an analytical method to detect the degree of heating in milk. A novel approach using nano liquid chromatography-orbitrap fusion mass spectrometer was developed for screening and identifing thermally sensitive peptides markers in the milk heating process (below 100 °C). This method integrates untargeted proteomics and chemometric tools to analyze protein quantitation data from differently heat-treated milk. Thirteen potential markers were screened out and identified, and further confirmed using by standard substances. Then, the accurate concentrations of 13 potential markers determined by isotope-dilution ultra-performance liquid chromatography-tandem triple quadrupole mass spectrometry were further mining the highly specific and thermally sensitive peptides markers. And Four peptides—INLFDTPLETQYVR, FELLGCELNGCTEPLGLK, QFQFIQVAGR, and GEADALNLDGGYIYTAGK—were selected as marker peptides to differentiate normal pasteurized milk from overheated pasteurized milk. The concentrations of INLFDTPLETQYVR ranges from 150 ± 11 µg/L to 350 ± 23 µg/L, while the concentrations of FELLGCELNGCTEPLGLK ranges from 40 ± 5 µg/L to 92 ± 3 µg/L, can distinguish normal pasteurized milk from overheated pasteurized milk. QFQFIQVAGR indicates overheated pasteurized milk at 230 ± 21 µg/L, and GEADALNLDGGYIYTAGK signifies 750 ± 43 µg/L. This study provides new insights for distinguishing overheated pasteurized milk.

Effects of saccharides on the contents of furfural compounds in modified milk

In Chinese dairy products, various saccharides including sugar substitutes are often added to modified milk or milk beverages to enhance flavor or increase benefits. That might result in the formation of furfural compounds due to the Maillard reaction between reducing sugars and proteins during heat treatment of milk. The contents of furfural compounds in dairy products vary depending on the type and proportion of sugars added, as well as the strength of heat treatment. Three monosaccharides, four disaccharides and two polysaccharides were selected to study the influences of saccharides on furfurals in modified milk. Kinetics parameters for the formation of furfural compounds were also studied under pilot processing conditions. The contents of furfurals in milk increased with the addition of monosaccharide, in the following order (from high to low) of type: fructose > galactose > glucose, and increased with the decrease in the polymerization degree of the added saccharides. The resulted prediction equations could be used to estimate the contents of furfurals in modified milk added with glucose, maltose or glucan after heat treatment at 115 °C–135 °C. This paper could provide a reference for the prediction and control of furfurals when applying saccharides in the dairy industry.

Influence of αs1-casein genetic variant in buffalo milk and rennet coagulation properties

Buffalo milk, recognized for its rich composition, including higher levels of fat, lactose, protein, and ash when compared to cow milk, has been insufficiently studied considering its genetic diversity within the buffalo population in Serbia. This study focuses on the analysis of the CSN1S1 472G&gt;C variant and its potential impact on rennet coagulation properties, critical for cheese production. Rennet coagulation parameters (rennet coagulation time (RCT), setting time (ST), aggregation rate (AR), and gel firmness (GF)), along with fresh curd yield (Yf), were examined in both, raw and high heat-treated buffalo milk. Genotyping results, obtained through Sanger sequencing of blood samples from 30 female buffaloes, revealed the presence of three CSN1S1 472G&gt;C genotypes: GG, GC, and CC. The rheological measurements, conducted using dynamic small amplitude oscillatory rheology (SAOR), indicated significant statistical differences (p&lt;0.05) among the tested parameters for these CSN1S1 472G&gt;C genotypes in both raw and heat-treated buffalo milk. In addition, the influence of genotype on the yield of fresh curd in fresh and thermally treated milk was studied. These results can contribute to optimization in the process of production and processing of buffalo milk, emphasizing the importance of understanding the genetic factors in the composition of buffalo milk and its technological properties.

Design and Development of Continuous Ohmic Heater for Milk and Its Performance Study

Present study aimed for the design and development of a continuous ohmic heating system for heating of milk. The holding capacity of the designed heater was 8.24 litre and had a 'tube in tube' type arrangement. The heat transfer area of the ohmic heater was increased by employing two stages, consisting of SS-316 pipes. Process was controlled by using an electrical panel equipped with all the required electrical components. The designed ohmic heater for milk was optimized for heating of milk temperature up to 73°C. Efficient heating of milk was heated at optimized conditions of 137.7 V (stage-1) and 72.2V(stage-2) with 1.5 l/min flowrate. The average heating rate for milk 4.6˚C/min. At optimized conditions, system performance co-efficient was found to be 86.95. The milk heated using ohmic heater showed no significant difference in the composition and sensory attributes when compared to the conventional heating method. Moreover, the alkaline phosphatase test was also parallel to the thermal heating system and milk was highly acceptable by the sensory panel and cost is considerably lower than the thermal system.

AUTHENTICITY ANALYSIS OF 100% SHEEP'S BRYNDZA FROM SELECTED ESTABLISHMENTS IN THE SLOVAK REPUBLIC

Cheese was in the past, and still is today, one of the leading commodities. The production of “bryndza” has been preserved over the years, and today it is represented by the Protected Geographical Indication “Slovenská bryndza” (Slovenská bryndza). There are two types of “Slovenská bryndza”, mixed or 100% sheep. However, the name 'traditional' belongs only to sheep's bryndza. The high demand for a particular foodstuff also brings risks associated with its quality and fairness. The same is true of the national heritage product, sheep's bryndza. Identifying the originality or authenticity of various animal food products has received considerable attention recently. Our work has focused on the control of adulteration of 100% sheep's bryndza. Purchased samples from different parts of Slovakia were analyzed with a focus on the addition of cow's milk to sheep's bryndza. The reference method for determining the presence of cow's milk in sheep's cheese is based on detecting cow's γ2- and γ3-caseins from cheese after electrophoretic separation on urea-polyacrylamide gels. This method has proven to be reliable and sensitive. We tested sheep's bryndza made from both raw milk and heat-treated milk. The method of checking for adulteration of the cheese proved successful and in one sample we found the presence of cow casein in smaller amounts, probably due to accidental contamination. Isoelectric focusing of γ-caseins after plasmolysis is suitable for qualitatively determining sheep and cow proteins in traditional Slovak bryndza.

Recycling of expired cow milk for constructing multifunctional biomass nonfluorinated chromatic paint with superhydrophobicity

Through denaturation and amination of the mixture, consisted of expired cow milk, kaolin and gardenia yellow, in the hot organic solvent that contained alkaline aminosilane coupling agent, then adsorption of diverse acid dyes in the acid condition, thus obtaining active matrixes with different colors. By virtue of the non-catalyzed in-situ reaction among the acrylate groups of pentaerythritol ester compounds and the amino groups of obtained matrixes as well as long-chain alkyl amines, the biomass fluoride-free superhydrophobic doped paints was prepared, however the poor stability was reflected in its anti-wetting coating surface. Furthermore, in order to improve durable superhydrophobicity and multifunctionality of the expired cow milk-based water-repellent paint, the thermally denatured protein, originated from expired cow milk heating, was blended with nanoscale inorganic pigments to accept the before-mentioned procedures of amination and in-situ growth, consequently constructing the multifunctional biomass nonfluorinated chromatic paint with robust superhydrophobic function, moreover its coated fabrics had 155.7° of average contact angle and 1.5° of average sliding angle. Additionally, by only using synergy of complex denaturation and chemical coupling, the expired cow milk could be transformed into UV-photoluminescent nonfluorinated superhydrophobic color paint, the contact angle of such paint-coated fabric was 153.3° and its sliding angle was 2°. Based on the additional function of as-prepared biomass paints, the applications of non-wetted switchable fluorescence imaging as well as photothermal deicing were realized. We believe that the expired cow milk-based multifunctional paints can expand into the fields of outdoor protective textiles, decorative building materials, fluorescent falsification-preventing and ice protection.

Use of turbidimetry for determination of heat treatment intensity applied at pasteurization of milk

Express methods for estimating the intensity of heat treatment of milk are necessary in industry and in research work. For this reason, there are many ways to measure this parameter, which are based on different physical principles, including turbidimetric methods. The Harland &amp; Ashworth turbidimetric method has been developed for a long time, however, due to its high reliability and ease of implementation, it is still used in practice. However, this method has a drawback: it takes a long time to perform the analysis. In this regard, the aim of the work is to develop an express method for evaluating the thermal class of milk based on the principle of measuring the concentration of soluble whey proteins. The result is achieved through the use of a turbidimetric measurement method with optimized sample preparation parameters and parameters for measuring the optical density of a suspension of protein aggregates. The method is implemented as follows. The milk sample is mixed with 0.1 N acetate buffer (pH 4.6) in a ratio that allows to obtain a concentration of soluble milk whey proteins from 0.05% to 0.1%. Recommended dilution coefficients: 1:3 for samples of ultra-pasteurized milk and pasteurized milk with high heat treatment intensity; 1:7 for samples of pasteurized milk with low heat treatment intensity and 1:14 for raw milk samples. The solution is filtered on a membrane filter with a pore size of 0.45 microns. The resulting filtrate is mixed with 24% trichloroacetic acid (TCA) in a 1:1 ratio to coagulate soluble whey proteins and form protein aggregates. After holding for 5–10 minutes, the optical density of the suspension of protein aggregates is measured at a wavelength of 650 nm. The content of water-soluble whey proteins in the sample can be calculated according to the calibration curve. The developed method allows to obtain the measurement result in less time than the Harland &amp; Ashworth turbidimetric method.

Influence of a natural colorant powder from Syzygium cumini L. (skeels) on sensorial and physicochemical properties during storage of a heat-treated flavored fermented milk

This study aimed to evaluate the influence of a powder colorant obtained from a hydroalcoholic extract of jambolan (Syzygium cumini) on the chemical, microbiological, and sensory characteristics of heat-treated flavored fermented milk. The extraction of anthocyanins from the pulp was carried out by maceration with 90% (v/v) ethanol acidified with citric acid. This extract was concentrated (14 to 15% w/v of total solids). Maltodextrin DE 12 was added to obtain 25% (w/v) total solids. Guar gum (0.06% w/w) was added as a stabilizer to whole milk reconstituted with sterilized distilled water (11% w/v total solids). The colorant powder was homogenized at a rate of 1.5 and 2 g per 100 mL of powdered whole milk dissolved in the corresponding amount of water, and sucrose and concentrated strawberry flavoring were added. The natural colorant addition allowed us to obtain a product with pH (4.23-4.75), titratable acidity (1.28-1.47% w/w lactic acid), and color stability, similar to those of yogurt with synthetic colorants. No microbial growth or color changes were detected. The judges did not notice any strange odor, taste, or color. Natural colorants can be a beneficial option for developing healthy and sustainable foods. Keywords: Syzygium cumini; anthocyanins; spray-dried; natural colorant; heat-treated fermented milk.

Influence of a natural colorant powder from Syzygium Cumini L. (Skeels) on sensory and physicochemical properties during storage of a heat-treated flavored fermented milk

This study aimed to evaluate the influence of a powder colorant obtained from a hydroalcoholic extract of jambolan (Syzygium cumini) on the chemical, microbiological, and sensory characteristics of heat-treated flavored fermented milk. The extraction of anthocyanins from the pulp was carried out by maceration with 90% (v/v) ethanol acidified with citric acid. This extract was concentrated (14 to 15% w/v of total solids). Maltodextrin DE 12 was added to obtain 25% (w/v) total solids. Guar gum (0.06% w/w) was added as a stabilizer to whole milk reconstituted with sterilized distilled water (11% w/v total solids). The colorant powder was homogenized at a rate of 1.5 and 2 g per 100 mL of powdered whole milk dissolved in the corresponding amount of water, and sucrose and concentrated strawberry flavoring were added. The natural colorant addition allowed us to obtain a product with pH (4.23-4.75), titratable acidity (1.28-1.47% w/w lactic acid), and color stability, similar to those of yogurt with synthetic colorants. No microbial growth or color changes were detected. The judges did not notice any strange odor, taste, or color. Natural colorants can be a beneficial option for developing healthy and sustainable foods. Keywords: Syzygium cumini; anthocyanins; spray-dried; natural colorant; heat-treated fermented milk.

Factors affecting the coagulation of milk protein during quark cheese processing in Vietnam

In recent years, cheese consumption in Vietnam is markedly rising, leading to the attention of local milk processors on cheese making. Quark-type cheese, a traditional food in Central Europe, is a type of well-known acid-coagulated cheese product. Milk coagulation properties (MCPs) play an important role to the success of the cheese-making process and are influenced by different parameters. In this study, the quality of raw milk for cheese making and the coagulation conditions in quark-type cheese processing were investigated. Raw milk collected from Phu Dong dairy farm met the requirement of Vietnamese standard for cheese making. The appropriate conditions for coagulation were identified: the heat treatment of milk at 60°C for 15 minutes, coagulation temperature at 40oC and pH 5.5, CaCl2 concentration at 0.04g/l. Under these conditions, a short coagulation time (72.33 seconds) and high curd yields (50.70%) were obtained. These results suggested that quark-type cheese using raw milk in Vietnam could be successfully developed at larger scale.