Textural and sensory properties of a calcium-induced milk gel

The textural and sensory properties of a calcium-induced milk gel prepared by heating skim milk with 7-20 mM added calcium chloride were investigated. Gel strength and water holding capacity of the gel increased and syneresis decreased during storage at 7 °C for 28 days at all calcium concentrations. Sensory studies showed that the gels were acceptable at added calcium concentrations of 7-13.5 mM; at higher concentrations, the sensory scores were lower. Adding sugar and flavours did not affect formation of the gels but increased their sensory scores

Magnesium in milk

This review draws attention to the significance of magnesium in milk, both the technical and human health aspects. Magnesium has been subject to less research than calcium in both aspects. Magnesium is present in cows' milk in ∼10% of the concentration of calcium. About two-thirds of the magnesium is soluble, whereas about one third of calcium is soluble. Although magnesium is less significant than calcium in dairy systems, it warrants more investigation. Magnesium plays numerous physiological roles in the human body and is implicated in many critical health issues such as metabolic syndrome and skeletal muscle loss. Despite its well-established significance in health, magnesium is often reported as an under-consumed nutrient. Milk and dairy products are already one of the main sources of dietary magnesium. There is an opportunity to develop milk and dairy products as efficient vehicles for supplementary dietary magnesium delivery with more research into fortification options

Draft genome comparison of representatives of the three dominant genotype groups of dairy Bacillus licheniformis Strains

The spore-forming bacterium Bacillus licheniformis is a common contaminant of milk and milk products. Strains of this species isolated from dairy products can be differentiated into three major groups, namely, G, F1, and F2, using random amplification of polymorphic DNA (RAPD) analysis; however, little is known about the genomic differences between these groups and the identity of the fragments that make up their RAPD profiles. In this work we obtained high-quality draft genomes of representative strains from each of the three RAPD groups (designated strain G-1, strain F1-1, and strain F2-1) and compared them to each other and to B. licheniformis ATCC 14580 and Bacillus subtilis 168. Whole-genome comparison and multilocus sequence typing revealed that strain G-1 contains significant sequence variability and belongs to a lineage distinct from the group F strains. Strain G-1 was found to contain genes coding for a type I restriction modification system, urease production, and bacitracin synthesis, as well as the 8-kbp plasmid pFL7, and these genes were not present in strains F1-1 and F2-1. In agreement with this, all isolates of group G, but no group F isolates, were found to possess urease activity and antimicrobial activity against Micrococcus. Identification of RAPD band sequences revealed that differences in the RAPD profiles were due to differences in gene lengths, 3' ends of predicted primer binding sites, or gene presence or absence. This work provides a greater understanding of the phylogenetic and phenotypic differences observed within the B. licheniformis species

Effects of High-Temperature Milk Processing

In this entry, high temperature is defined as 90 to 150 °C. Many dairy processes, including extended shelf-life (ESL) and ultra-high-temperature (UHT) processing, in-container sterilization, yogurt milk heat treatment, pre-heating or forewarming milk for production of sterile concentrated milk and powders, manufacture of co-precipitate and dolce de leche, involve heat treatments in this temperature range. Pasteurization is not included in this entry as it is generally performed at 72–75 °C

Practical consequences of calcium addition to and removal from milk and milk products

Calcium in milk is significant for both its nutritive value and its key role in many functional properties of milk and milk products. Manipulating its concentration, particularly of the ionic form, alters the properties of the products and facilitates or hinders certain processing operations. Stability to thermal treatment is the major property affected, but several others such as gelation, coagulation and foaming are influenced by either adding or removing calcium. This article reviews the manipulation of the calcium content of several products and its practical consequences for dairy processing

A survey of Australian consumers' attitudes towards UHT milk

A telephone survey was conducted in Melbourne and Brisbane to obtain a profile of milk consumption in Australia and determine consumers' attitudes regarding UHT milk. It was anticipated that this survey would reveal the reasons for the low level of UHT milk consumption in Australia. Pasteurised milk was the main milk type used by more than 80% of respondents. For UHT milk this figure was much lower (approximately 10%), even though two thirds of respondents had tried UHT milk. Factors that were found to influence UHT milk consumption included existing milk consumption habits, consumer perception, flavour and price. The majority of non-users of UHT milk stated habit of using other milk type as their main reason for not using UHT milk. Other reasons included poor nutritional value, poor flavour and not real/pure milk, indicating a negative consumer perception of the product. The flavour of UHT milk was identified as a problem, with nearly half of UHT milk users considering it to be worse than the flavour of pasteurised milk. However, a small proportion of UHT milk users preferred the flavour of UHT milk, with the majority of them stating that it was creamier, richer and/or stronger than the flavour of pasteurised milk. Prior to post-farmgate deregulation, price was shown to discourage consumers from using UHT milk. At the time of the survey, post-farmgate prices in Victoria were deregulated resulting in UHT milk being priced below that of pasteurised milk in some instances. This was believed to contribute to a significantly higher market share of the product in Melbourne than in Brisbane

Blocked lysine in dairy products: formation, occurrence, analysis, and nutritional implications

Lysine residues in milk proteins become “blocked” when they react with reducing sugars, particularly lactose, in the Maillard reaction. The blocked or glycated lysines reduce the biological availability of the lysine to metabolic processes and also hinder hydrolysis of the parent protein by digestive enzymes. Heating and storage of milk and milk products are the major promotants of the Maillard reaction and resulting chemical damage to the proteins. Several methods have been proposed to estimate the extent of this protein damage. Two major compounds, furosine, a product of acid hydrolysis of lactulosyl-lysine, the 1st stable product of the Maillard reaction, and carboxymethyl-lysine are used for assessing the early and advanced stages of the Maillard reaction, respectively. In addition, several methods are used for assessing the bioavailability of lysine in a protein; these include chemical, enzymic, and animal-based methods. This review discusses the Maillard reaction and its significance in milk and dairy products, methods of assessing the extent of the reaction and of the bioavailability of lysine, and the nutritional significance of blocked lysines and associated Maillard reaction products in milk proteins