Effects of microbial transglutaminase levels on donkey cheese production

Microbial transglutaminase (MTGase) is an enzyme widely used in the dairy sector to improve the functional properties of protein-based products via the formation of a network between protein molecules. The aim of this study involving cheese from the milk of donkeys was to evaluate the effects of treatment with MTGase at the concentrations of 0 (control), 5, 8 and 10 U/g milk protein on the cheese-making process parameters, as well as the physical and chemical characteristics of the resulting cheese. MTGase influenced the time of gel formation from rennet addition (P < 0.05), with a delay at the two highest concentrations, accompanied by a lower (P < 0.01) pH of cheese and the lowest (P < 0.01) loss in cheese weight at 24 h of storage. The highest gel viscosity (P < 0.01) was observed at the highest concentration of the enzyme, reaching the value of 70 mPa⋅sec after 60 min. The chemical composition and color of the cheeses were not significantly affected by the inclusion of MTGase, regardless of the enzyme concentration. These findings may be of relevance in adapting the cheese-making process and might help in the design of new dairy products from donkey's milk.

Transglutaminase Applications in Dairy Technology

Consumers' expectations from a dairy product have changed dramatically during the last two decades. People are now more eager to purchase more nutritious dairy foods with improved sensory characteristics. Dairy industry has made many efforts to meet such expectations and numerious production strategies and alternatives have been developed over the years including non-thermal processing, membrane applications, enzymatic modifications of milk components, and so on. Among these novel approaches, transglutaminase (TG)-mediated modifications of milk proteins have become fairly popular and such modifications in dairy proteins offer many advantages to the dairy industry. Since late 1980s, a great number of researches have been done on TG applications in milk and dairy products. Especially, milk proteins-based edible films and gels from milk treated with TG have found many application fields at industrial level. This chapter reviews the characteristics of microbial-origin TG as well as its mode of action and recent developments in TG applications in dairy technology.

Yield and Textural Characteristics of Panela Cheeses Produced with Dairy-Vegetable Protein (Soybean or Peanut) Blends Supplemented with Transglutaminase

The study evaluated panela cheeses made from dairy-plant protein blends, using soybean or peanut protein isolates, supplemented with transglutaminase (TG). Plant proteins were isolated using an alkaline extraction method followed by acid precipitation, and added to the dairy system in order to increase 50% or 100% the protein concentration. The total protein extraction for peanut and soybean isolates was 30.3% and 54.6%, respectively (based on initial protein content of sources), and no impairment of their essential amino acid profile was detected. Cheeses supplemented with TG and soybean showed the highest moisture and crude yield (>67.8% and 20.7%, respectively), whereas protein content was higher in the peanut isolate--added samples without TG (>67.4%). Cheese solids yield (ratio between final and initial solids) was higher for treatments with TG and 100% of plant protein addition (>50.7%). Regarding texture, 4 parameters were measured: hardness, cohesiveness, chewiness, and springiness. All cheeses containing soybean isolates and TG presented the highest chewiness and cohesiveness values, similar to those of the control treatment. Springiness was similar for all treatments, but hardness was higher in cheeses prepared with the peanut protein isolate added with TG. From these results it can be concluded that panela cheeses can be elaborated following a traditional procedure, but with the addition of soybean or peanut protein to the dairy ingredients. Cheeses containing these protein isolates showed higher protein than the milk control cheese and similar textural characteristics.

Digestibility of transglutaminase cross-linked caseinate versus native caseinate in an in vitro multicompartmental model simulating young child and adult gastrointestinal conditions

Aim of this study was to investigate the digestion of transglutaminase cross-linked caseinate (XLC) versus native caseinate (NC) in solution and in cheese spread under digestive conditions for adults and children mimicked in a gastrointestinal model. Samples were collected for gel electrophoresis and nitrogen analysis. The results showed no relevant differences between XLC and NC for total and α-amino nitrogen in digested fraction under adult and child conditions. However, the rate of digestion was depending on the food matrix. Gel electrophoresis showed the gastric breakdown of XLC without formation of pepsin resistant peptides larger than 4 kDa. NC was slowly digested in the stomach with formation of pepsin resistant fragments and was still detectable in the stomach after 90 min. In the small intestine the proteins were rapidly digested. XLC was digested to small peptides, while NC was resistant against pepsin digestion under gastric conditions of adults and children.