Subject: Transport and storage of milk and milk products

The key factor in the transport and storage of short shelf-life products is temperature control throughout the whole distribution chain. A typical distribution chain is analysed and some of the problem areas discussed. The effect of temperature on cream, desserts, yoghurt and cottage cheese are considered to highlight possible problems of poor distribution.     

Subject: Transport and storage of milk and milk products

Reference is made to the anticipated completion of churn conversion by 31st July, 1979. The main designs of bulk milk tanks currently in use on farms in England and Wales and the milk cooling systems associated with them are illustrated and discussed. Cleaning systems for both refrigerated and non-refrigerated tanks are described and their relative effectiveness indicated. Methods intended to reduce energy requirements and costs in connection with milk cooling are discussed. The relative importance of bulk milk storage equipment and other sources of contamination on the hygienic quality of refrigerated bulk milk is considered.     

Subject: Transport and storage of milk and milk products

The factors affecting the condition of milk at the end of its stay in bulk storage are as follows: The temperature of the milk when put into storage; the bacteriological quality of the milk when put into storage; the state of cleanliness of the storage tank or silo and allied equipment at time of filling; the length of time the milk is held in storage, and each of these is dealt with individually. The current performance of incoming ex-farm milk temperature is reviewed and the necessity to store milk at temperatures below 4C where lengthy storage time is involved, is stressed. The general bacteriological condition of present-day incoming raw supplies is discussed and emphasis placed on the importance of exploiting the potential advantages of bulk collection to the full. The importance of good management of bulk stored supplies is underlined and tank cleaning and milk agitation discussed. The more pressing problems in dairy products directly associated with raw milk quality are discussed in some detail and the need for more informative and relevant testing methods considered. Reference is made to the proposed DTF Survey on Raw Milk Quality and a strong appeal made for this to be supported in full by the industry.     

Subject: Standardization of milk and milk products Future trends in standardization

European Economic Community and United Kingdom regulations relating to the composition of liquid milk are reviewed, and sales of the various categories of drinking milk in Member States of the EEC and in the United States are discussed in relation to total sales. Some of the advantages and disadvantages of standardized liquid milk from the consumer, producer, processor, and UK national interest point of view are highlighted. An opinion is expressed that there will be an increase in sales of low-fat varieties of milk in the UK in the next decade. We question whether current regulations are too restrictive.     

Subject: Developments in assessing milk quality Use of membrane filtration for assessing the hygienic quality of milk and milk products

The hygienic quality of milk can be assessed by counting bacteria and somatic cells and quantifying sediment. Membrane filtration can be used to concentrate these components before quantification. The DEFT count, which uses membrane filtration and eprfluorescent microscopy, is a new rapid. sensitive, inexpensive method for counting bacteria and somatic cells in milk. Its use should permit better control and management of supplies and reduce the risk of poor quality milk products arising from high bacterial counts in the raw material. A new method of measuring sediment in milk based on membrane filtration, microscopy, and TV image analysis is being developed at the NIRD .     

Standardisation of milk for cheesemaking at factory level

The percentage of milk fat recovered as cheese varies between 85 and 93 per cent, depending on the system used, and this must be taken into account when the casein to fat ratio of milk for cheesemaking is selected. Seasonal variation in the composition of milk protein can have a significant influence on the potential cheese yield. Prolonged storage of milk may cause casein losses while heat precipitation can facilitate the incorporation of whey proteins in cheese curd. The economic consequences of seasonal variations in Ireland on the price of milk for cheesemaking are discussed. The economics of standardisation may be marginal, but it is a useful aid in achieving uniform cheese quality.     

Major advances in fresh milk and milk products: fluid milk products and frozen desserts

Major technological advances in the fluid milk processing industry in the last 25 yr include significant improvements in all the unit operations of separation, standardization, pasteurization, homogenization, and packaging. Many advancements have been directed toward production capacity, automation, and hygienic operation. Extended shelf-life milks are produced by high heat treatment, sometimes coupled with microfiltration or centrifugation. Other nonthermal methods have also been investigated. Flavored milk beverages have increased in popularity, as have milk beverages packaged in single-service, closeable plastic containers. Likewise, the frozen dairy processing industry has seen the development of large-capacity, automated processing equipment for a wide range of products designed to gain market share. Significant advancements in product quality have been made, many of these arising from improved knowledge of the functional properties of ingredients and their impact on structure and texture. Incidents of foodborne disease associated with dairy products continue to occur, necessitating even greater diligence in the control of pathogen transmission. Analytical techniques for the rapid detection of specific types of microorganisms have been developed and greatly improved during this time. Despite tremendous technological advancements for processors and a greater diversity of products for consumers, per capita consumption of fluid milk has declined and consumption of frozen dairy desserts has been steady during this 25-yr period.     

Nutrient content of milk and milk products: vitamins of the B complex and vitamin C in retail market milk and milk products

A survey was undertaken to update and extend information on the water-soluble vitamin content of milk and milk products on retail sale. The results are discussed in relation to previously published data. Apart from vitamin C the levels of vitamins in retail pasteurized cows' milk were very similar to those found in milk from the processing dairy. Levels of total vitamin C and folic acid in UHT full cream milk were negligible; vitamin B₆ and vitamin B₁₂ were respectively 73 and 56% of the levels in pasteurized milk. Except for nicotinic acid, pantothenic acid and biotin, the levels of vitamins in sterilized milk were lower than in pasteurized milk, particularly vitamin C, folic acid and vitamin B₁₂. When compared on an equivalent dilution basis, vitamin B₆, thiamine, folic acid and, especially, vitamin B₁₂ in evaporated milk were lower than in pasteurized cows' milk. In comparison, in full cream condensed milk only vitamin B₆ was particularly low; vitamin C was particularly well preserved. With the exception of vitamin B₁₂, vitamin levels in reconstituted spray dried milk were similar to those in pasteurized cows 'milk. Levels in filled' spray dried milk were on average 70% of those in ordinary dried milks. Apart from vitamin B₁₂ the levels of B vitamins in non health food yogurt were generally higher than in pasteurized milk, especially folic acid. The levels of vitamin B₁₂ and folic acid in goats' milk were only 22 and 11 % respectively of those in cows' milk, but the nicotinic acid level was four times higher. The level of vitamin C in raw sheep's milk was about five times that in pasteurized cows' milk; other levels, apart from folic acid which was similar, were between 1.3 and 5.2 times those in cows' milk.     

Hormones in bovine milk and milk products: A survey

A survey of the published data on the occurrence of hormones in milk and milk products is presented. Bovine milk and colostrum contain a large number of hormones from either steroidic or peptidic origin. The main categories to which these molecules belong are gonadal (estrogens, progesterone, androgens), adrenal (glucocorticoids), pituitary (prolactin, growth hormone) and hypothalamic hormones (GRH, LH-RH, TRH). Other molecules, such as proteins related to the parathyroid hormone, insulin, somatostatin, calcitonin, bombesin, erythropoeitin and melatonin, are also of interest. The exact role of hormones in the development of the newborn is still not known, but it is believed that they may contribute to the growth of the newborn and to the development and maturation of its gastrointestinal and immune systems.     

Acidophilus milk products: Manufacture and therapeutics

Abstract

Consumption of acidophilus milk products as a dietary adjunct is considered to impart many health benefits. These include (i) control of intestinal infections, (ii) stabilization of intestinal micro‐flora, (iii) control of serum cholesterol level, (iv) prevention of colon cancer, and (v) enhanced availability of nutrients. However, L. acidophilus grows slowly in milk, which results in overgrowth of other microorganisms present. Hence, acidophilus milk products are characterized by an unpleasant flavor and are not acceptable as a normal component of diet. Attempts have, therefore, been made to manufacture acceptable acidophilus milk products possessing wider consumer appeal. The manufacturing and therapeutical aspects of acidophilus milk products are discussed in this review.     

Peanut milk and peanut milk based products production: a review

Since the early 1950s, numerous reports have been published suggesting that peanut milk and peanut milk based products can be prepared in a wide variety of ways. Emphasis has shifted from preparing inexpensive milk like beverages, very nutritious but somewhat lacking consumers appeal, to using the peanut milk or peanut protein isolates as an animal milk extender without changing flavor, to develop more attractive fermented products, and to precipitate proteins from the milk in order to get a curd called "tofu," and to produce cheese analogs. Great attention has been paid to the improvement of the stability, sensory properties, and shelf-life of the milk, using physical and chemical treatments. Many efforts have been deployed for supplementing the products. Thanks to recent advances, the removal of aflatoxin from peanut milk can be achieved using Flavobacterium aurantiacum as a biodegradater. It has also found application as liquid coffee whitener. However, despite all these developments and publications, there is still a need for much more diversified studies in order to definitely overcome the stability, the nutty flavor, and sensory problems always encountered when producing peanut milk and some peanut milk based products.     

Nutrient content of milk and milk products: water soluble vitamins in baby milk formulae

A study of the content of water soluble vitamins in the 12 baby milk formulae available in the UK in April 1983 showed that levels of vitamins in the individual brands were generally in excess of those declared by the manufacturer. For cows' milk based formulae the mean excess of vitamins over the declared level was 94%. Vitamin levels in prepared formulae averaged three times the minimum recommended level. The average level of B vitamins in prepared cows' milk based formulae was six times higher than in mature human milk. For the two soya based products, the levels of vitamins were generally in excess of the declared level and levels of vitamin B12, biotin and, in one sample, vitamin B6 were considerably in excess of those found in mature human milk.     

乳及乳制品加工中的美拉德反应

针对乳及乳制品在加工和储藏过程中由于发生美拉德反应不仅使乳制品的营养物质受到破坏，还产生对人体有害的物质，在很大程度上影响的乳制品的质量，对乳制品中美拉德反应的历程，产生的标志物及其测定方法等进行了的综述。     

Nitrate-reducing microorganisms in milk products and human milk

The quantitative determination of nitrate-reducing microorganisms in food is important because of their role in the formation of N-nitroso compounds and methemoglobin. The total counts of microorganisms and the counts of nitrate-reducing microorganisms were assayed in various milk products and in human milk by the method of the most probable numbers using nitrate broth medium. The mean value and standard deviation of the nitrate-reducing microorganisms were the following: in pasteurized milk 3.4 +/- 1.1 log/ml (in spring and summer 4.2 +/- 1.1, and in winter 2.8 +/- 0.6 log/ml), in kefir "Tallinn' 2.9 +/- 1.1 log/ml, in fat kefir 2.9 +/- +/- 0.7 log/ml, in sour milk 3.9 +/- 0.5 log/ml, in fresh milk 4.6 +/- 0.6 log/ml and in human milk 2.7 +/- +/- 1.1 log/ml. The amount of nitrate-reducing microorganisms in pasteurized milk of the spring-summer period and in fresh milk was significantly higher than in human milk. The mean count of nitrate-reducing microorganisms in human milk is regarded as a maximum permitted count of these organisms in milk for bottle-fed sucklings. For them and for atrophic gastritis patients pasteurized or fresh milk should be boiled.     

Recent aflatoxin survey data in milk and milk products: A review

Aflatoxin M₁ (AFM₁) occurrence in human and animal milk, infant formula, powdered milk, cheese and yoghurt represents a risk for health. The last four years (2010–2014) of data, as well as the most frequently and updated analytical methods applied for AFM₁ quantification, are evaluated. Aflatoxin B₁, considered the most potent toxic aflatoxin, is metabolised to form the monohydroxy derivative AFM₁. This metabolized, expressed in the milk, is relatively stable, and it is not eliminated by heat treatments or pasteurisation, and thus represents a serious health concern.     

Titrimetric studies on milk and milk products.

Potentiometric acid-base titration is a simple method that can be used successfully in the investigation of the protein system of milk and other protein-containing products. Its applications include the examination of conventional heating procedures, cheese ripening, the investigation of processed cheese and the effect of melting salts. The principle depends on the performance of pH-dependent phase transitions which are recorded by a single titration cycle and evaluated quantitatively by means of hysteresis loops.     

The shelf-life of dairy products: 2. Raw milk and fresh products

In the second of this series of articles, the specific factors controlling the shelf-life of raw milk, pasteurized milk and cream, cottage cheese and yogurt are considered. The shelf-life of raw milk depends on the quality of the milk ex-farm and on subsequent transport and storage conditions. Shelf-life may be enhanced by deep cooling or thermization. Post heat treatment contamination by Gram negative psychrotrophic bacteria is the major determinant of shelf-life of pasteurized products. In cultured dairy products, yeast and mould contamination is the most usual cause of spoilage.     

Subject: 'Skim milk' Technology of skimmed milk evaporation

The paper seeks to show how the requirements of skimmed milk concentration are met in modern evaporators and how the type of plant used has developed over the years, the falling film tubular evaporator now being virtually standard. Very economical operation is now possible with sophisticated multiple-effect plants with thermocompression, and further economies are possible with mechanical vapour recompression. The importance of adequate wetting of heat transfer surfaces is discussed with regard to length of run and achievable concentration, and methods of maintaining correct wetting conditions are illustrated. Preheating is an important feature of such evaporators for both economy and control of final powder properties, and the methods adopted are described, Finally, the control of modern skimmed milk evaporators is considered briefly.     

Standardisation of the calcium content of whey protein‐free milk concentrate

The calcium content of a cheese greatly influences its textural properties. This study aimed to reduce the calcium content of milk retentate by microfiltration in a three‐stage process, carried out in triplicate. During microfiltration at 50 °C, the permeation of calcium was higher (P > 0.005) with acidified (pH 5.75) feed than with nonacidified feed. The concentration of calcium correlated linearly (R² > 0.98) with the protein content of retentate with the use of acidified and nonacidified feed. However, the slope was lower with acidified retentates, and calcium–protein ratio can be reduced only when acidified retentate was used as a feed.