Milk Coagulation Research Articles

β-casein A2 affects milk renneting properties, cheese yield before and after ripening, and alters the texture of Caciotta cheese produced in field conditions.

The aim of this study was to investigate the effect of β-CN genetic variants on milk coagulation properties, curd and cheese yield, efficiency of cheesemaking, and quality of Caciotta cheese after 15 d of ripening. Thirty-three cheesemaking experiments were carried out in one on-farm pilot-scale dairy plant. For each cheesemaking day, small groups of cows were selected and milked separately to obtain 2 milk pools, one with high proportion of β-CN A1 and B in β-CN (A1B milk) and one with high proportion of β-CN A2 (A2 milk) in β-CN, respectively. Each milk pool originated from at least 2 cows and was processed into Caciotta cheese, producing 2 cheese wheels of commercial size. Differences across milk pools in milk composition, coagulation properties, curd yield measured by laboratory-scale micro-cheesemaking, cheese yield after stewing, brining, and 15 d of ripening, whey composition, recovery rates, as well as cheese composition, color and texture were estimated using a set of mixed linear models including the random effect of the processing day, and the linear effects of the major sources of variation of the investigated traits. Compared with A1B milk, A2 milk had a remarkably 2.8-min longer rennet coagulation time, lower curd yield measured by micro-cheesemaking (-0.5%), cheese yield after stewing (-1.15%), brining (-0.92%), and 15-d ripening (-0.36%). No significant variations associated with the milk pools were observed in cheese composition, but cheese from A2 milk exhibited significantly lower a* and higher hue angle values compared with cheese processed from A1B milk, although these differences are not expected to be perceived by human eye. Cheese from A2 milk was also characterized by a significantly lower hardness, springiness, chewiness, and gumminess than cheese from A1B milk. Our results indicate that use of A2 milk for cheese production leads to inferior technological properties and a less efficient cheesemaking process. More studies are necessary to investigate the impact of β-CN variants on product quality and consumer perception.

Proteases from an Amazonian Mushroom Species: A Mycotechnological Alternative for the Production of Milk Coagulant.

Edible mushrooms have been used as sustainable sources of proteases of industrial interest. The aim of this research was to investigate the influence of different culture media on mycelial growth and the potential of an Amazonian mushroom species, Auricularia fuscosuccinea DPUA 1624, in the biosynthesis of bovine milk coagulant enzymes. The species was cultivated on Sabouraud agar, malt, glucose, and peptone agar, malt extract agar, and glucose and peptone agar, supplemented with yeast extract for mycelial development. Enzyme biosynthesis was evaluated by submerged fermentation. Subsequently, the cultures were incubated at 28°C for 8days. Proteolytic and coagulant activities were determined using 1% azocasein solution and milk powder as substrates, respectively. In the results of radial growth speed of A. fuscosuccinea, the values were significant in the GYP and SAB + YE culture media. However, GYP agar favored the growth and mycelial vigor of A. fuscosuccinea; therefore, this medium was selected to obtain inoculum in the tests. In submerged fermentation, the MGYP medium favored the synthesis of proteases for A. fuscosuccinea and synthesized coagulant proteases in 100% of the media, in which significant activity was observed in SAB + YE. The significant production of coagulant proteases of A. fuscosuccinea was obtained under the following conditions: inoculum size 10%, 8days of fermentation period, and 8days of inoculum age. The results indicate that A. fuscosuccinea DPUA 1624 has potential for use in industrial manufacturing, especially in dairy products.

Interfacial composition of coenzyme Q10 emulsions impacts coagulation of fortified milk during gastric digestion

Interfacial composition of coenzyme Q10 emulsions impacts coagulation of fortified milk during gastric digestion

Cysteine Peptidases of Calotropis procera (Apocynaceae): A Literature Review on their Biochemical Properties and Potential Applications.

The latex of the xerophytic plant Calotropis procera, popularly known as giant milkweed, contains a complex mixture of secondary metabolites and proteins and has attracted the attention of many researchers. Several bioactive laticifer enzymes from C. procera have been studied for their potential applications in the medical, agricultural and food industries. The present work aimed to review the current scientific knowledge on cysteine peptidases from the latex of this plant, highlighting their biochemical properties and possible uses as biotechnological tools. Bibliographic databases (PubMed, Scopus and Web of Science) were searched for scientific works published in the last six decades reporting the purification, biochemical characterization, molecular cloning and potential applications of laticifer cysteine peptidases from C. procera. Since the first works published in the late 1960s on the occurrence of thiol peptidases in this species, five cysteine peptidases (procerain, procerain B, CpCP-1, CpCP-2 and CpCP-3) have been purified and biochemically characterized. The characterized enzymes are members of the subfamily C1A of sulfhydryl proteases, showing the characteristic biochemical and structural features of papain and related proteins. Several biological activities of the purified enzymes have been demonstrated, including the inhibition of phytopathogenic fungi and milk coagulation properties, which may be of practical use. Moreover, pharmacologically active propeptides released from the posttranslational processing of C. procera cysteine peptidase zymogens have been shown to be promising therapeutic agents against cancer cells. Further research is needed to provide a better comprehensive understanding of the mode of action and biosafety of these molecules.

Food utility potential of protease obtained from insect‐commensal Bacillus subtilis AU‐2

AbstractBACKGROUNDBacillus subtilis AU‐2, isolated from the gut of Tribolium castaneum, was used for protease production. The purified protease was evaluated for its potential in food‐related applications including meat tenderization, milk coagulation, and the preparation of enzymatic soybean hydrolysates. Enzymatic hydrolysis of soy protein is an effective method for producing protein hydrolysates with optimal techno‐functional properties.RESULTSThis study confirmed that B. subtilis AU‐2 is a commensal with T. castaneum, within the insect gut flora. The purified protease obtained from B. subtilis AU‐2 exhibited meat tenderization activity and an ability to promote milk coagulation within a 20 min timeframe. Soybean hydrolysate prepared using the protease exhibited a relatively higher degree of hydrolysis (20.1%) than pepsin, trypsin, and papain. The sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) peptide fragmentation pattern of the enzymatically prepared soy protein hydrolysate revealed the disappearance of ~35 kDa protein bands after 4 h protease treatment. The prepared soy protein hydrolysate showed improved emulsifying capacity (EC) (705 mL g−1) and exhibited significant 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) antioxidant activity (77.89%) and hydroxyl (OH) radical scavenging activity (97.23%).CONCLUSIONSThe protease obtained from the newly isolated B. subtilis AU‐2 strain exhibited potential for food‐related applications, including meat tenderization, milk clotting, and soybean hydrolysate preparation. Its accessibility opens avenues for utilization in the food processing industry. © 2024 Society of Chemical Industry.

Comparative Study of Coagulation Dynamics: Cardoon Flower Extract vs. Chymosin

Milk coagulants play a crucial role in defining curd characteristics. The objective of this study was to compare the coagulation dynamics of two commonly used coagulants in cheesemaking: cardoon flower extract (Cynara cardunculus L.) and commercial chymosin, using sheep milk from four different origins in the Baixo Alentejo region of Portugal, as the substrate. Milk composition was determined using the MilkoScan 133B, while the milk-clotting time (MCT) was measured following ISO 23058/IDF 199:2006 guidelines with slight modifications and coagulation kinetics, and technological properties were evaluated using the Optigraph apparatus. The results demonstrate that the type of coagulant impacts the coagulation properties of sheep milk. Pearson’s correlation analysis indicated that milk samples with higher protein content exhibited longer coagulation times but resulted in firmer curds. On the other hand, the use of cardoon flower extract introduced greater variability compared to chymosin, with a delayed onset of coagulation, reduced curd firmness, and increased variability in enzymatic kinetics. These results suggest that cardoon extract, while traditional, introduces greater heterogeneity in curd formation compared to the more consistent action of chymosin.

Phenotypic Differentiation of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus Isolates Found in Yogurt Starter Cultures

The mutualistic relationship between Streptococcus thermophilus (S. thermophilus) and L. delbrueckii subsp. bulgaricus (L. bulgaricus) is responsible for milk coagulation, gel formation, and the flavour of yogurt. Under set-style yogurt processing conditions, the performance of a mixed culture composed of these species depends on key technological parameters such as the capacity for acidification and proteolytic activity. This study aimed to determine the extent of phenotypic diversity by comparing the key traits of acidification and proteolytic activity among isolates found in yogurt starter cultures. Seventy-two isolates from three industrial starter cultures were ranked by either their fast or slow acidification activity (time to reach pH 4.6, 16 h), proteolytic activity, cell envelope proteinase (CEP) activity, redox potential and titratable acidity. The integration of multiple phenotype measures by hierarchical clustering and non-metric dimensional scaling (NMDS) clustered groups of isolates by multifactor similarity. A significant difference (p-value < 0.05) was observed between the clusters regarding redox potential and the proteolytic activity of both S. thermophilus and L. bulgaricus. The integration of multiple phenotypes points to the diversification that may have occurred over repeated culturing of yogurt starter bacteria. The phenotypic diversity may explain the divergence in starter performance and be used to refine the formulation of new starter cultures. Future work will investigate the correlation between the activity of specific enzymes based on the phenotype to explain the separation between the fast and slow acidification of isolates.

Processing and Evaluation of Paneer from Coconut Milk and Cow Milk Blends

Paneer is an Indian traditional milk product which occupies an important place as a base product for the production of various culinary preparations. Paneer is a nutritious and wholesome food. It provides one of the methods of conserving, preserving and prolonging shelf life of milk solids in a highly concentrated form.For coagulation of milk 1% of lime juice, which contains citric acid. The shelf life of the developed product during room temperature (3 days) and refrigerated condition. The present study was under taken with different levels (90:10, 80:20, 70:30) of cow milk and coconut milk. Chemical quality (moisture, fat, protein, and yield) and microbial quality (TPC, yeast and mould, coliform) were also analyzed. The coconut paneer with 90:10 ratio of cow milk and coconut milk was found to be best among others. Thus as far as product acceptability judged by organoleptic evaluation the treatment can be rated as P0 > P1> P2> P3. The fresh cow milk paneer (P0) chemical constituents were 50.78 g of moisture, 0.22% of acidity, 5.3 of pH, 20.39 g of protein, 22.8 g of fat, 0 g of fibre, 198 mg /100 g of calcium, 2.2 mg /100 g of iron respectively. The coconut paneer prepared by 10% coconut milk blending with 90% cow milk, the P1 sample chemical constituents were 52.05 g of moisture, 0.20% of acidity, 5.6 of pH, 20.55 g of protein, 23.75 g of fat, 0 g of fibre, 192mg /100 g of calcium, 3.12 mg of iron respectively. The overall acceptability score was observed as highly acceptable with score point of 8.4±0.70in P1 when compared to control P0 was 8.1±0.73. The unit cost production of 100 g of the functional coconut paneer was Rs.25/100gwhereas control was Rs.22/100 g of packets respectively.

Exploring cheese production enzymes from various plants as an alternative to Calf rennet

Milk coagulation, traditionally relied on Calf rennet, is a crucial enzymatic process in cheese production. Ethical and practical constraints in using Calf rennet have led to the exploration of alternative sources. This study aimed to identify plant-based substitutes for calf rennet by investigating the coagulating potential of extracts from three plants: Calotropis procera, lemon, and Solanum incanum. Each plant tested with three extract levels (15, 20, and 25 ml), and replicated three times. Juices were extracted from lemon and Solanum incanum fruits through incision and squeezing. Meanwhile, Calotropis procera aqueous filtrates were separated from its polymeric gum using centrifugation. Then after, all extracts were further purified through muslin cloth and Whatman filter paper. Extracts were added to a beaker containing 500 ml of milk heated at 50 °C, and allowed to coagulate, resulting in the separation of cheese, curds and whey. Then after whey production, fresh and dry weights of cheese, and cheese yield percentage were measured and recorded. Statistical analysis using SAS Studio showed that there is highly significant differences with P < 0.0001 among plant extracts in their effects on the cheese-making potential. For all extract levels, the highest cheese-dry weight and percentage of cheese yield were observed in Calotropis procera and the lowest cheese formation starting times observed from lemon juice. These findings offer insights into optimizing cheese-making processes using natural sources and suggest that Calotropis procera, along with lemon juice and Solanum incanum, could serve as alternative sources of rennet.

Effect of cheese coagulants on American-style natural cheese proteolysis and functional characteristics of process cheese made therefrom

Recombinant bovine chymosin (RBC) is an enzyme routinely used in cheese manufacture. Recombinant camel chymosin (RCC) is a milk coagulant with higher clotting activity and less proteolytic activity for natural cheese manufacture. This study aimed to determine the effect of RCC and RBC on the proteolysis of natural cheese and the functionality of processed cheese (PC). Six American-style natural cheeses were manufactured utilizing two different chymosin treatments and used to produce PC at 1 month of ripening. The natural cheese made using RCC had a significantly (P < 0.05) lower level of primary proteolysis and a lower degree of hydrolysis of αS1-CN and β-CN. The RCC treatment's hot viscosity, hardness, and loss tangent were significantly (P < 0.05) higher than the RBC in the PC. These results demonstrate that RCC results in a reduced level of primary proteolysis in a natural cheese, and when utilized in PC, it increases firmness and decreases meltability.

Production of a fungal aspartic protease via solid‐state fermentation using a rotating drum bioreactor

AbstractBACKGROUNDSolid‐state fermentation (SSF) has gained attention recently as a promising approach for producing a range of high‐value industrial products. SSF has several benefits, including a high product yield, a lesser chance of contamination, a resemblance to some fungi and bacteria's native environment, a lower energy need, and cost‐effectiveness. Additionally, the enzyme extraction from concentrated solutions facilitates the recovery procedure. Mucor racemosus, a filamentous fungus, has the potential to produce a milk‐clotting enzyme (aspartic protease) cultivated on various combinations of the solid media to investigate the effect of media on the production and activity of the milk‐clotting enzyme.RESULTSThe fermentation was scaled up by utilizing Terrafors‐IS Infors HT in‐situ sterilizable rotating solid‐state bioreactor to cultivate the fungus. The effect of agitation (rotation on the day of inoculation and day 1), aeration (air flow rates of 1 L and 2 L/min), and moisture content (60% and 90%), during SSF were investigated. The profiles of various operational parameters (that is, temperature, pressure, flow rate, exit O2, and exit CO2) were monitored using the provided software, and data were collected at 10‐min intervals during the whole course of fermentation. The results suggest that aeration has a remarkable effect on the quantity of biomass produced, but it doesn't assure high enzyme production. The highest milk clotting activity of ~570 U/mL was recorded with a moisture content of 60% and a flow rate of 1 L/min.CONCLUSIONA high yield of ~570 U/mL of the enzyme with desired characteristics was obtained with minimum moisture availability at low temperatures. The results narrated in this study validate the SSF process for producing aspartic protease from wheat bran using a rotating solid‐state bioreactor to be used as a potential milk coagulant in the cheese industry. © 2024 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry (SCI).

Sensory Evaluation of Chhana Burfi Process with Jackfruit (Artocarpus hetrophyllus L.) Pulp

The study was conducted at Dept. of Animal Husbandry and Dairy Science, Dr. BSKKV, Dapoli, Ratnagiri, Maharashtra, India during August 2021 to May 2022 to evaluate the suitability of Jackfruit pulp as flavouring agent in developing flavoured Chhana Burfi and its production cost. Basically, Cow milk required for preparation of Chhana, Citric acid used for Coagulation of milk, Sugar and Jackfruit pulp etc. was required to conduct this research. The curd mass obtained when milk is coagulated with the organic acids such as citric acid at higher temperature and after subsequent drainage of whey, mass of curd obtained is called chhana. Chhana was used as base material for preparation of chhana burfi. The Chhana Burfi was prepared from cow milk by incorporating jackfruit pulp @ 10% (F1), 15% (F2), and 20% (F3) and two sugar level i.e. 15% (S1) and 18% (S2) On the basis of weight of Chhana. All treatment is analyzed for sensory characteristic i.e. colour and appearance, body and texture, flavour and overall acceptability by using 9-point Hedonic scale. Present study investigated that jackfruit pulp could be successfully utilized for preparation of flavoured chhana burfi. The most acceptable quality flavour Chhana Burfi could be prepared by using 15% jackfruit pulp and 18% sugar. Prepared delicious milk product i.e. Jackfruit flavour Chhana Burfi rich taste and flavour along with nutritional value. The production cost of Jackfruit flavour Chhana Burfi (most acceptable level i.e.S2F2) was Rs. 355.8/- per kg.

Particle size distribution of total mixed rations fed to Italian Mediterranean buffaloes measured by the PSPS: impact on milk quality and digestibility

Buffalo breeding in Italy is becoming increasingly economically attractive, with milk production in the Lazio region growing by 15% since 2004. However, the optimal physical characteristics of total mixed rations (TMR) have not been thoroughly investigated. This lack of research suggests the need for greater attention to the physical characteristics of diet, which, combined with its chemical properties, may negatively impact milk yield (MY) and milk quality (MQ), as seen in dairy cows. Therefore, the objective of this study was to assess the effect of diet composition, with a particular focus on the physical component, on MY and MQ, and apparent digestibility (AD) of dairy buffaloes. The study was conducted on 10 dairy buffalo farms in Amaseno valley (Italy). Monthly samples of TMR, faeces, and bulk milk were collected over a 12-month period, alongside interviews with farmers to gather information on MY and diet composition. The results revealed a high variability in the physical-chemical composition of diets across farms, attributable to differences in feeding management practices. Both chemical and physical component were found to be associated with MY, MQ and AD changes. A ration poor in roughage and rich in concentrate negatively affected MQ showing lower milk fat, and higher somatic cells count and milk urea, while a greater presence of coarse particles and high fibre were associated with lower MY. Nevertheless, coarse particles and aNDF were positively associated with milk clotting parameters and aNDF digestibility. Our study emphasised the high importance of fibre for improving MQ of dairy buffaloes.

Cell immobilization for enhanced milk clotting enzyme production from Bacillus amyloliquefacien and cheese quality

BackgroundMilk clotting enzymes, essential for milk coagulation in cheese production, are obtained from the stomach of young ruminants, an expensive and limited source. This study was accomplished by finding a suitable alternative. Bacterial isolates recovered from honey were screened for milk clotting enzyme activity. and further, by immobilization of the microorganisms to enhance stability and facilitate their repeated use.ResultThe most effective enzyme was produced by a microbe identified as Bacillus amyloliquefaciens based on 16 S rRNA sequencing. The cells were encapsulated in Ca2+ alginate beads. These beads retained complete enzyme production after being used five times. Glucose and Soybean were selected as the most favorable carbon and nitrogen sources, respectively. The optimum temperature for activity was 35 ℃ for both free and immobilized cells but as the temperature was increased to 55 °C and above, the encapsulated form retained more activity than the free cells. The pH optimum shifted from 6.5 to 7 for the free cells to 7–7.5 for the immobilized cells. The immobilization process decreased the activation energy for enzyme production and activity, prolonged the enzyme half-life, and increased the deactivation energy. Enzyme produced by immobilized cells generated a more compact cheese.ConclusionsThe finding of this study was to identify a less expensive source of milk-clotting enzymes and confirm the success of cell immobilization in improving cell rigidity and stability. Also, immobilization of this B. amyloliquefaciens strain offers an enzyme source of value for industrial production of cheese.

Innovative Approaches to Camembert Cheese: Optimizing Prebiotics and Coagulation Conditions for Enhanced Quality and Nutrition

The objective of this study is to investigate how different factors, such as lactic acid bacteria, prebiotics (flaxseed powder, watercress seed powder, okra mucilage), and coagulation temperature influence the final quality of curd by conducting three optimization experiments and implementing a structured experimental plan. In the first phase, milk coagulation was assessed at 45 °C with various combinations of lactic acid bacteria (probiotics) and prebiotics (powdered flaxseed and watercress). In the second investigation phase, the effects of lowered probiotic and prebiotic (powdered flaxseed and watercress) concentrations were examined at the coagulation temperature of 38 °C. We investigated the concentration of lactic acid bacteria at 3 mg/mL of milk and the effects of temperature and prebiotics (okra mucilage and flaxseed powder). We observed short milk clotting time (2 s) using the optimized mixture (0.18 mg of probiotics, 1.5 mg of flaxseed powder, and 1.147 mg of watercress powder) per 10 mL of milk. It contrasts with the classical coagulation way optimized at (5.9 and 9.5 s), which were generated at optimal temperatures of 45 and 45.7 °C, respectively. Our new mixture improves the fermentation process of camembert cheese at 38 °C. This cheese had a high flavonoid content, fewer lactic bacteria and molds, a homogeneous texture, and no outer crust, and exceptional sensory attributes such as a creamy and fluid paste. These attributes suggest its potential benefits as a dairy product for individuals with cardiovascular and gastrointestinal conditions.

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.

Comparative genomics and phenotypic assessment of lactic acid bacteria isolated from artisanal cheese as potential starter cultures

Novel starter cultures are coveted by the dairy industry for enhancing the sensory, quality, and safety attributes of fermented dairy products. In this study, artisanal cheeses were investigated as a source of novel starter cultures. Lactic acid bacteria (LAB) were isolated from the cheese and underwent an antimicrobial activity screening. Six potential antimicrobial producers were selected for whole genome sequencing and were confirmed to be new LAB strains belonging to the genera Lacticaseibacillus, Lactococcus, Leuconostoc, and Enterococcus. Genes associated with carbohydrate utilization, proteolytic enzyme production, and exopolysaccharide synthesis were identified. Additionally, in silico analysis revealed safety-related traits including absence of antibiotic resistance genes, intact prophage regions, and biogenic amine production genes. Genome-guided phenotypic confirmation of important identified traits was completed, which included utilization of multiple carbohydrates, hydrolysis of casein, coagulation of milk, and susceptibility to antibiotic. Among these LAB strains, Lactococcus lactis OSY-92 contained and expressed the necessary genes for a dairy starter culture. The strain displayed anti-Gram-positive antimicrobial activity, a strong preference for lactose and galactose, limited casein hydrolysis, and ability to coagulate milk in 7.5 h. When all these findings were considered, L. lactis OSY-92 qualified as a potential novel and safe starter culture for dairy fermentations.

Influence of physicochemical factors on the specific activity of proteases used in cheesemaking biotechnology

The formation of a clot under the influence of proteolytic enzymes is an essential stage in cheesemaking technology. Depending on their composition, milk-clotting enzyme preparations have a different effect on the quality characteristics of the clot, whey separation, and yield of the finished product. At present, the Russian market offers a wide range of domestic and imported milk-clotting enzyme preparations. In this connection, the choice of a milk coagulant by cheese makers should be carried out in accordance with the cheese group produced by the enterprise. The milk-clotting activity of enzyme preparations depends not only on the active acidity of the mixture, but also on the temperature of the solution used to obtain them. It is the solution temperature that has a determining effect on the duration of the coagulation process and, therefore, the quality of the formed clot. Research into the specific activity of milk-clotting enzyme preparations, obtained in a working solution with different active acidity (pH from 4.0 to 8.0), showed their milk-clotting activity to decrease significantly upon pH shifting to the alkaline region. Application of solutions with a pH of 4.0 led to an increase in the milk-clotting activity of bovine pepsin, VNIIMS SG-50 rennet-bovine preparation, and rennet enzyme by 94, 72, and 36%, respectively, relative to the control. Bovine pepsin demonstrated the highest sensitivity to fluctuations in active acidity. A study into the effect of substrate temperature in the range from 30 to 40 °C established rennet to be the most sensitive preparation to temperature changes. It is concluded that a properly selected enzyme composition is an effective means for affecting the quality of cheese products.

Comparative analysis of the quality of buffalo milk fresh cheese processed with Moringa oleifera seed milk coagulant and calf rennet

This study aimed to evaluate the impact of buffalo milk fresh cheese produced using M. oleifera seed milk coagulant and calf rennet. No significant difference was found between composition and functional characteristics (P > 0.05). M. oleifera seed milk coagulant cheese exhibited smaller pore size, a more uniform conformation and a denser network structure compared with calf rennet cheese. Moreover, hardness, adhesiveness, and chewiness of calf rennet cheese were significantly higher compared with M. oleifera seed milk coagulant cheese (P < 0.05). The storage modulus of both cheeses was greater than the loss modulus, thus indicating viscoelastic behavior. Moreover, the elastic gel formed in M. oleifera seed milk coagulant cheese exhibited superior stability. In addition, the content of phosphoserine, glutamic acid, long-chain fatty acids, medium-chain fatty acids, saturated fatty acids, monounsaturated fatty acids, aldehydes, esters, and lactones was significantly higher in M. oleifera seed milk coagulant cheese compared with calf rennet cheese (P < 0.05). In addition, a strong correlation was found between free amino acids, free fatty acid (FFA), and volatile flavor compounds. The findings of this study provide a theoretical foundation for the application of M. oleifera seed milk coagulant as a new plant milk coagulant resource in the dairy industry.

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.