A. Zamora

Effect of fat content and homogenization under conventional or ultra-high-pressure conditions on interactions between proteins in rennet curds

The objective of this study was to investigate the influence of conventional and ultra-high-pressure homogenization on interactions between proteins within drained rennet curds. The effect of fat content of milk (0.0, 1.8, or 3.6%) and homogenization treatment on dissociation of proteins by different chemical agents was thus studied. Increasing the fat content of raw milk increased levels of unbound whey proteins and calcium-bonded caseins in curds; in contrast, hydrophobic interactions and hydrogen bonds were inhibited. Both homogenization treatments triggered the incorporation of unbound whey proteins in the curd, and of caseins through ionic bonds involving calcium salts. Conventional homogenization-pasteurization enhanced interactions between caseins through hydrogen bonds and hydrophobic interactions. In contrast, ultra-high-pressure homogenization impaired hydrogen bonding, led to the incorporation of both whey proteins and caseins through hydrophobic interactions and increased the amount of unbound caseins. Thus, both homogenization treatments provoked changes in the protein interactions within rennet curds; however, the nature of the changes depended on the homogenization conditions.

Ultra-high pressure homogenisation of milk: technological aspects of cheese-making and microbial shelf life of a starter-free fresh cheese.

Fresh cheeses from pasteurised (80 °C for 15 s), homogenised-pasteurised (15 + 3 MPa at 60 °C; 80 °C for 15 s) or ultra-high pressure homogenised milks (300 MPa and inlet temperature of 30 °C) were produced in order to evaluate different technological aspects during cheese-making and to study their microbial shelf life. Although the coagulation properties of milk were enhanced by ultra-high pressure homogenisation (UHPH), the cheese-making properties were somewhat altered; both conventional homogenisation and UHPH of milk provoked some difficulties at cutting the curd due to crumbling and improper curd matting due to poor cohesion of the grains. Cheese-milk obtained by UHPH showed a higher microbiological quality than milk obtained by conventional treatments. Starter-free fresh cheeses made from UHPH-treated milk showed less syneresis during storage and longer microbiological shelf-life than those from conventionally treated milk samples.

Effect of inulin addition on the sensorial properties of reduced‐fat fresh cheese

A reduced-fat fresh cows milk cheese with inulin (3%) was compared with both full-fat and reduced-fat cheeses without the prebiotic. The pH and microbiological quality of cheeses were not affected by the presence of inulin. Cheeses produced with inulin were less hard, springy, cohesive and chewy than reduced-fat cheeses, and more similar to cheeses made from whole milk. Cheeses produced with inulin had the lowest lightness and the highest yellowness values, although these colour differences were not detected by the panellists. The sensory panel described the reduced-fat cheese with inulin as more acceptable than its counterpart without inulin.

High-Pressure Homogenization for Structure Modification

Abstract The need for enhancing microbial food safety, shelf-life, and quality, without negatively altering the sensory, functional, technological, and nutritional characteristics of foods, has led to increased interest in innovative low-temperature technologies for food preservation. Among these technologies, high-pressure homogenization has been identified as a particularly promising technology for processing liquid foods. The aim of this chapter is to present the potential application of ultrahigh-pressure homogenization with respect to classical homogenization and heat treatments applied to animal and vegetable milks, dairy products (cheese and yogurt), and fruit juices, and to discuss their effects on the main structures and components of these products and on their technological properties.

Compositional and biochemical changes during cold storage of starter-free fresh cheeses made from ultra-high-pressure homogenised milk.

The aim of the present study was to evaluate the effects of using ultra-high pressure homogenisation (UHPH) on the composition and biochemistry of starter-free fresh cheeses and to monitor their evolution during cold storage as an alternative to conventional treatments applied in the production of fresh cheese such as conventional pasteurisation and homogenisation-pasteurisation. Although both homogenisation treatments increased cheese moisture content, cheeses from UHPH-treated milk showed lower moisture loss during storage than those from conventionally homogenised-pasteurised milk. Lipolysis and proteolysis levels in cheeses from UHPH-treated milk were lower than those from conventionally treated milk samples. Although, oxidation was found to be the major drawback, in general terms, high quality starter-free fresh cheeses were obtained from UHPH-treated milk.