Cheese proteolysis and matrix disintegration during in vitro digestion

Hybrid Paneer: Influence of mung bean protein isolate (Vigna radiata L.) on the texture, microstructure, and in vitro gastro-small intestinal digestion

Replacing dairy proteins with legume proteins such as mung bean protein can create hybrid cheese alternatives with superior nutritional and functional properties. The effects of partially replacing (30%) cow milk with mung bean protein isolate (MBPI) on the rheology, texture, microstructure, and digestibility of paneer (acid-heat coagulated cheese) were studied. The developed hybrid cow milk-mung bean paneer (CMMBP) had higher protein and moisture contents, lower fat content, and a darker colour than cow milk paneer (CMP). CMMBP showed a significant reduction in hardness, cohesiveness, chewiness, and springiness compared to the cow milk-based control. Frequency sweeps performed using a dynamic rheometer showed higher storage modulus (G') for CMMBP compared to CMP, indicating greater elastic properties of the hybrid paneer. In vitro digestibility of CMMBP was significantly lower than CMP, as shown by the lower overall ninhydrin-reactive free amino N release and the presence of resistant peptides at the end of digestion.

Influence of food oral processing, bolus characteristics, and digestive conditions on the protein digestibility of turkey cold meat and fresh cheese

During mastication, foods are progressively transformed to achieve swallowable boluses and their characteristics are crucial for the subsequent digestion events. The main goal of this work was to evaluate the impact of food oral processing, bolus properties, and different digestive conditions on the protein digestibility of turkey cold meat and fresh cheese. In vivo normal and deficient masticated food boluses were prepared by a young volunteer. Besides, three digestion models were used to simulate the different physiological conditions frequently observed in adults and the elderly, presenting good or poor oral health: i) Normal Masticated-Normal Digested model; ii) Deficient Masticated-Normal Digested model; and iii) Deficient Masticated-Elderly Digested model. The oral processing behaviour (number of chews, chewing time, chewing rate, and saliva uptake), bolus particle size, textural and viscoelastic properties of boluses, and protein digestibility of samples were determined. Results showed that deficient masticated boluses exhibited lower amounts of saliva uptake and greater particle sizes, hardness, stiffness, and rigidity, notably in deficient masticated turkey cold meat boluses. Moreover, the worst digestive scenario (Deficient Masticated-Elderly Digested model) negatively impacted on the proteolysis extend of samples, especially for total soluble proteins and soluble peptides contents. The current study demonstrates that the oral processing behaviour and degree of food fragmentation impacted on the granulometric, texture, and viscoelastic properties of both food boluses, whereas the worst digestive scenario commonly observed in the elderly reduced the proteolysis extend of the products evaluated.

Effects of Pre-Emulsification with Thermal-Denatured Whey Protein on Texture and Microstructure of Reduced-Sodium Processed Cheese

Thermal-denatured whey protein-milk fat emulsion gels with different degrees of pre-emulsification were prepared by pre-emulsifying milk fat with thermal-denatured whey protein and used in the preparation of reduced-sodium processed cheeses. The effect of the thermal-denatured whey protein pre-emulsification process on the texture and microstructure of reduced-sodium processed cheeses was evaluated by studying the composition, color, texture, functional properties, microstructure and sensory analysis of the processed cheeses. The results showed that compared with cheese without pre-emulsified fat (1.5% ES control), the moisture content of cheese with pre-emulsified 100% fat (1.5% ES100) increased by 5.81%, the L* values increased by 7.61%, the hardness increased by 43.24%, and the free oil release decreased by 38%. The microstructure showed that the particle size of fat was significantly reduced, and the distribution was more uniform. In addition, compared with the cheese added with 3% emulsifying salt (3% ES control), the amount of emulsifying salt in the 1.5% ES100 decreased by 50%, but the fat distribution of the two kinds of cheese tended to be consistent, and there was no obvious change in texture characteristics and meltability. Sensory scores increased with the increase in pre-emulsification degree. Overall, the pre-emulsification of milk fat with thermal-denatured whey protein can reduce the sodium content of processed cheese and improve its quality.

Impact of Milk Storage and Heat Treatments on In Vitro Protein Digestibility of Soft Cheese

Cheese is an important source of protein in the human diet, and its digestibility depends on its macro and microstructure. This study investigated the effect of milk heat pre-treatment and pasteurization level on the protein digestibility of produced cheese. An in vitro digestion method was used considering cheeses after 4 and 21 days of storage. The peptide profile and amino acids (AAs) released in digestion were analyzed to evaluate the level of protein degradation following in vitro digestion. The results showed the presence of shorter peptides in the digested cheese from pre-treated milk and 4-day ripening while this trend was not observed after 21 days of storage, showing the effect of storage period. A significantly higher content of AAs was found in digested cheese produced from milk subjected to a higher temperature of pasteurization, and there was a significant increase in total AA content in the cheese after 21 days of storage, confirming the positive effect of ripening on protein digestibility. From these results emerges the importance of the management of heat treatments on the digestion of proteins in soft cheese.

Higher microbial diversity in raw than in pasteurized milk Raclette-type cheese enhances peptide and metabolite diversity after in vitro digestion

Numerous bacteria are responsible for hydrolysis of proteins during cheese ripening. The raw milk flora is a major source of bacterial variety, starter cultures are needed for successful acidification of the cheese and proteolytic strains like Lactobacillus helveticus, are added for flavor improvement or acceleration of ripening processes. To study the impact of higher bacterial diversity in cheese on protein hydrolysis during simulated human digestion, Raclette-type cheeses were produced from raw or heat treated milk, with or without proteolytic L. helveticus and ripened for 120 days. Kinetic processes were studied with a dynamic (DIDGI®) in vitro protocol and endpoints with the static INFOGEST in vitro digestion protocol, allowing a comparison of the two in vitro protocols at the level of gastric and intestinal endpoints. Both digestion protocols resulted in comparable peptide patterns after intestinal digestion and higher microbial diversity in cheeses led to a more diverse peptidome after simulated digestion.