Effects of Genetic Variants of κ-casein and β-lactoglobulin and Heat Treatment of Milk on Cheese and Whey Compositions

J W Choi,K F Ng-Kwai-Hang

doi:10.5713/ajas.2002.732

Abstract

Milk samples with different phenotype combination of κ-casein and β-lactoglobulin and different preheating temperatures of 30, 70, 75 and 80°C were used for cheesemaking under laboratory conditions. For the 853 batches of cheese, mean composition was 59.64% total solids, 30.24% fat and 23.66% protein, and the whey contained 6.93% total solids, 0.30% fat and 0.87% protein. Least squares analysis of the data indicated that heating temperature of the milk and κ-CN/β-LG phenotypes had significant effects on cheese and whey compositions. The total solids, fat and protein contents of cheese were negatively correlated with preheating temperatures of milk. Cheese from BB/BB phenotype milk had the highest and those from AA/AA phenotype milk had the lowest concentrations of total solids, fat and protein. Mean recoveries of milk components in the cheese were 53.71% of total solids, 87.15% of fat, and 80.32% of protein. For the 10 different types of milk, maximum recoveries of milk components in cheese occurred with preheating temperature of 70°C or 75°C and lowest recoveries occurred at 80°C. The whey averaged 6.94% total solids, 0.30% fat and 0.87% protein. Losses of milk components in the whey were lowest for milk preheated at 80°C and for milk containing the BB/BB phenotype. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 5 : 732-739)

Highlights

MATERIALS AND METHODSThe two most important cheese characteristics that are of interests to the cheesemaker are its yield and quality which is dependent on its composition
Both yield and quality of cheese are affected by composition of milk (Lou and Ng-Kwai-Hang, 1992a, 1992b) and genetic variants of milk proteins (Marziali and Ng-Kwai-Hang, 1986a, 1986b; Ng-Kwai-Hang and Grosclaude, 2002)
The increase in cheese yield by several of the above methods is accompanied by changes in cheese and whey compositions

Summary

MATERIALS AND METHODS

The two most important cheese characteristics that are of interests to the cheesemaker are its yield and quality which is dependent on its composition. Several attempts have been made to increase cheese yield (Lau et al, 1990; Marshall, 1986) by the inclusion of non-casein proteins into the cheese This has been achieved by the processing of milk prior to cheesemaking and includes ultrafiltration and heat processing (Zall and Chen, 1986), pH cycling (Singh et al, 1988), denaturation of whey proteins (Lawrence, 1993). The present study investigates, under laboratory conditions, the effects of genetic variants of milk proteins and heat treatments on cheese and whey compositions and incorporation of milk components into cheese. Throughout this study, procedures for milk collection, heat treatment of milk samples prior to cheesemaking, cheesemaking techniques under laboratory conditions, collection and weighing of milk, cheese and whey samples, analysing components in the original milk and the resulting cheese and whey were the same as previously described (Choi and Ng-Kwai-Hang, 1998). Subsamples of the initial milk used and corresponding whey samples were analysed in duplicate for total solids, fat and protein

Chemical analyses

Statistical analyses

Variability in cheese and whey composition

Protein in dry matter

Milk types