Lactococcus lactis DPC3147, a strain isolated from an Irish kefir grain, produces a bacteriocin with a broad spectrum of inhibition. The bacteriocin produced is heat stable, particularly at a low pH, and inhibits nisin-producing (Nip+) lactococci. On the basis of the observation that the nisin structural gene (nisA) does not hybridize to DPC3147 genomic DNA, the bacteriocin produced was considered novel and designated lacticin 3147. The genetic determinants which encode lacticin 3147 are contained on a 63-kb plasmid, which was conjugally mobilized to a commercial cheese starter, L. lactis subsp. cremoris DPC4268. The resultant transconjugant, DPC4275, both produces and is immune to lacticin 3147. The ability of lacticin 3147-producing lactococci to perform as cheddar cheese starters was subsequently investigated in cheesemaking trials. Bacteriocin-producing starters (which included the transconjugant strain DPC4275) produced acid at rates similar to those of commercial strains. The level of lacticin 3147 produced in cheese remained constant over 6 months of ripening and correlated with a significant reduction in the levels of nonstarter lactic acid bacteria. Such results suggest that these starters provide a means of controlling developing microflora in ripened fermented products.

An application in cheddar cheese manufacture for a strain of Lactococcus lactis producing a novel broad-spectrum bacteriocin, lacticin 3147.

The effect of fat content on the rheology, microstructure and heat-induced functional characteristics of Cheddar cheese

Membrane technology has revolutionized the dairy sector. Different types of membranes are used in the industry for various purposes like extending the shelf life of milk without exposure to heat treatment, standardization of the major components of milk for tailoring new products as well increasing yield and quality of the dairy products, and concentrating, fractionation and purification of milk components especially valuable milk proteins in their natural state. In the cheese industry, membranes increase the yield and quality of cheese and control the whey volume, by concentrating the cheese milk. With the advancement of newer technology

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Perspective of Membrane Technology in Dairy Industry: A Review

Publisher Summary This chapter discusses the physical, biochemical, and nutritional aspects of cheese. Cheese is the most diverse, most scientifically interesting, and most challenging group of dairy products. While most dairy products, if properly manufactured and stored, are biologically, biochemically, and chemically very stable, cheeses are biologically and biochemically dynamic and, consequently, inherently unstable. Cheese manufacture and ripening involves a complex series of consecutive and concomitant microbiological, biochemical, and chemical events, which, if synchronized and balanced, lead to products with highly desirable flavors, but when unbalanced, result in off-flavors. Considering that a basically similar raw material (milks from a very limited number of species) is subjected to a generally common manufacturing protocol, it is fascinating that such a diverse range of products can be produced.

Cheese: physical, biochemical, and nutritional aspects.

Incorporation of whey proteins in cheese

Skim milks were pre-acidified to pH 6·4 and concentrated by ultra-filtration to give retentates with protein levels of 210 g/1. Retentates were blended with skim milk and cream to give standardized milks with protein levels ranging from 30 to 82 g/1. These were used for the manufacture of Cheddar cheese in conventional equipment. Increasing milk protein level resulted in reduced gelation times, increased curd firming rates and a decrease in the set-to-cut time when cutting at equal firmness values (i.e. elastic modulus, G′, ∼ 16 Pa). As the curd firming rates increased with milk protein level, it became increasingly difficult to cut the curd cleanly, without tearing, before the end of the cutting cycle. Reflecting the tearing of curd, and consequent curd particle shattering, fat losses in the running wheys were greater than those predicted on the basis of volume reduction (due to ultrafiltration) for milks with protein levels > 50 g/1. Reduction of setting temperatures, in the range 31–27 °C, and the level of added rennet brought the set-to-cut times and curd firming rates of concentrated milks closer to those of the control milk. While increasing milk protein level in the range 30–70 g/1 had little effect on cheese composition, it resulted in slower proteolysis and maturation.

Effect of milk protein standardization, by ultrafiltration, on the manufacture, composition and maturation of Cheddar cheese

Rennet coagulation properties of retentates obtained by ultrafiltration of skim milks heated to different temperatures

Composition, microstructure and maturation of semi-hard cheeses from high protein ultrafiltered milk retentates with different levels of denatured whey protein

Rheological and textural properties of goat and cow milk set type yoghurts

The aim of this study was to analyze application of quality function deployment on examining the shelf-life of Agaricus bisporus Portobello packed in modified atmosphere packaging stored for 22 d at 4 °C. Mushrooms were packaged under three modified atmosphere packaging conditions: high nitrogen packaging (HNP); low carbon dioxide packaging (LCP); low oxygen packaging (LOP). Packaging with air inside initially was used as the atmosphere treatment (AIR). In respect to color changes, total color difference and browning index showed the greatest range for HNP and the smallest range for LOP. Regarding sensory analysis, LOP and AIR had the best results for overall quality compared to LCP and HNP. Odor characteristics were best scored for LOP while AIR had the worst impact on this feature. The highest level of quality deterioration was observed for LCP and HNP mushrooms while AIR mushrooms had the lowest level of deterioration. Quality function deployment showed that the best 'Quality Score' was for LOP, followed by AIR. LCP and HNP had the worst 'Quality Score' during the entire shelf-life.

Predrag Pudja

Papers

Effect of milk protein standardization, by ultrafiltration, on the manufacture, composition and maturation of Cheddar cheese

Rennet coagulation properties of retentates obtained by ultrafiltration of skim milks heated to different temperatures

Composition, microstructure and maturation of semi-hard cheeses from high protein ultrafiltered milk retentates with different levels of denatured whey protein

Rheological and textural properties of goat and cow milk set type yoghurts

Application of quality function deployment on shelf-life analysis of Agaricus bisporus Portobello