This status summary was prepared for participants in a National Workshop on Research Opportunities for the Dairy Foods Industry held in Berkeley, CA, November 1986. It presents brief discussions of regulations that influence progress in commercial manufacture of UHT products, equipment, and processes used in the US and elsewhere, changes in products during UHT processing and storage, some economic and consumer-related considerations, quality assurance for UHT products, and suggestions for future research.

Participants in the workshop, "Positioning the Dairy Industry to Meet Nutrition Issues of the '80's"

In the United States, public agencies long have been involved in providing information about food and nutrition. Over the years, however, the nature of that involvement has shifted. Initially the emphasis was on practical information about agriculture and home economics. Gradually emphasis has shifted to concerns about malnutrition and, more recently, to concerns about overconsumption and associated health problems. This paper reviews some of the food and nutrition-related activities of public agencies and summarizes some recent concerns related to nutrition "recommendations", "goals", and "guidelines". Two key publications related to nutrition issues are: 1) "Nutrition and Your Health: Dietary Guidelines for Americans," published jointly by United States Department of Agriculture and Department of Health and Human Services and 2) "Toward Healthful Diets," from the Food and Nutrition Board of the National Academy of Sciences. One of the guidelines in the former publication tends to encourage the dairy industry to orient toward reducing consumption of milk fat. In contrast, the analysis in the latter publication tends to encourage adoption of an approach to promote nutrition education and marketing programs without necessarily reducing consumption of milk fat. The approach of dairy industry would differ depending upon which guidelines were adopted.

Representatives of California's dairy industry participated in a 2-day workshop to examine nutrition

To determine whether dairy rations influence the accuracy of component analyses, fat, protein, lactose, and total solids were measured in milk produced by Holstein cows fed a basal ration or a ration containing either 7% extruded soybeans, 15% whole cottonseed, or 30% whole cottonseed for the first 15 wk postpartum. Samples from individual milkings were collected in the 14th and 15th wk from 12 or 13 cows in each group. Reference methods were Mojonnier for fat, Udy dye-binding for protein, polarimetry for lactose, and forced-air oven for total solids. The methods compared to reference methods were Milkotester and Babcock for fat and Infrared Milk Analyzer for fat, protein, lactose, and solids-not-fat. Fatty acid composition was determined by gas chromatography. For cows fed 30% whole cottonseed, Infrared Milk Analyzer fat measurements averaged .14% lower than by Mojonnier. For cows fed extruded soybeans or whole cottonseed, Milkotester fat measurements were higher than by Mojonnier, and Infrared Milk Analyzer protein measurements were higher than by Udy dye-binding. For cows fed whole cottonseed, Infrared Milk Analyzer solids-not-fat measurements were higher than by forced air oven. For cows fed extruded soybeans or whole cottonseed, differences between Babcock and Mojonnier fat measurements and between Infrared Milk Analyzer and polarimetric lactose measurements were not affected. For cows fed whole cottonseed, the mean molecular weight of the fatty aicds of milk fat was increased.

Four lactating Holstein cows producing about 21 kg milk/day were fed complete rations containing 0, 5, 15, and 25% whole cottonseed in a 4 X 4 Latin square design. Diets were fed ad libitum. Periods were 21 days in length with total collections of feces and urine during the last 7 days of each period. Digestibilities o nitrogen, lipid, and energy increased with increasing cottonseed in the diet. There were no significant effects of cottonseed on digestibility or availability of fiber components, calcium, phosphorous, and magnesium. Cottonseed feeding did not affect dry matter intake or milk yield but did increase yields of milk fat and fat-corrected milk and decrease milk protein and solids-not-fat percentages. Synthesis of fatty acid in the mammary gland was depressed by about 50% on the 25% cottonseed diet, but transfer of dietary fat resulted in twofold increases in yields of stearic and oleic acids. Hydrogenation of cottonseed fatty acid in the rumen resulted in a fourfold increase in yield of trans oleic acid in milk fat. Samples from bulk milk tank and data collected from 55 commercial dairies showed similar changes in fatty acid composition of milk from cows fed whole cottonseed. There was no apparent effect of feeding up to 2.9 kg cottonseed dry matter per cow per day on calving interval or on incidence of displaced abomasum, ketosis, milk, fever, or retained placenta.

in the world dairy market, Ireland led with an increase in milk production of over 100%, closely followed by the USSR and the Netherlands with increases exceeding 90%.Since 1956, milk production increased about 72% in France, 63% in East Germany, 62% in Poland, 59% in Italy, and more than 35% in West Germany and the United Kingdom.The milk production scene has shifted considerably since 1956 (Table 2).Many countries in a pronounced deficit position a quarter century ago have increased their milk output substantially.This trend is evident among Eastern European countries, USSR, and several Latin American countries.Only a few well established dairy countries, notably the Netherlands, Ireland, France, and West Germany, made substantial gains in milk production.More moderate gains in milk production were in Denmark, Finland, Norway, New Zealand, and Switzerland.Among the traditional dairy countries only in Sweden and Australia did total milk production decline significantly.Increases in milk yield per cow contributed substantially to the larger total milk output in all but three of the countries with comparative data.However, a large increase in cow numbers helped boost milk supplies in Japan, Israel, France, Ireland, Netherlands, Romania, Yugoslavia, and the USSR.Cow numbers accounted for most of the increase in Venezuela and Turkey.In contrast, Hungary, Italy, and the United Kingdom achieved substantial increases in milk production despite significant decreases in cow numbers.Total milk production increased substantially in both East and West Germany, but cow numbers remained relatively unchanged.Another group of countries basically maintained their total milk output despite a sharp drop in cow numbers, indicating a significant improvement in yield per cow.Argentina, South Africa, and Denmark head this group, but a change in definition of "cow numbers" may have contributed to the decline in cows reported.Although cow numbers dropped 48 and 38% in the United States and Canada, total milk production declined only slightly.Despite sharp declines in cow numbers, total milk production increased moderately in both Norway and Finland.Sweden and Australia experienced a drop in cow numbers of over 50% with a less drastic decrease in total milk production.Milk out-put in New Zealand increased approximately 16% with only a slight decline in cow numbers.

Electron microscopy was employed to follow changes in the casein micelles in milk through gelling and cooking. Scanning electron microscopy showed that casein micelles aggregated into chains, then strands and clusters, and eventually into amorphous masses. There was a decrease in porosity along with an increase in size of casein aggregates throughout the manufacturing process. Based on measurements of particles in transmission electron micrographs, casein micelles or fused particles increased in size during curd manufacture in three significantly different stages—in milk, during gelling and healing, and during cooking. Data, corrected by a statistical technique which accounted for all transmission electron microscopy slices not having been obtained through the micelle diameters, yielded average diameters of micelles of 87.6nm in milk, 181.6nm during early gelling, 184.9nm at the end of healing, 206.1nm during cooking, and 207.6nm at the end of cooking. Acid and culture set curds showed similar microstructures.

A current hypothesis is that a relatively impervious skin forms around curd particles of cottage cheese during healing and cooking. Comparisons were by both scanning and transmission electron microscopy of the surface and internal structures of small curd cottage cheese made commercially by the culture set method and on a laboratory scale by the direct acid set method. The photographic evidence, which is consistent with hundreds of visual scanning electron microscopy and transmission electron microscopy examinations, does not support the conclusion that a skin or similar impervious film forms around cottage cheese curd particles when conventional manufacturing procedures are used. However, an extreme heat treatment (1h at 70C) formed a surface skin. When typical cooking treatments are used, firming of the curd during healing and cooking is not attributable to formation of a skin at the curd surface. In modeling mass transport processes within cottage cheese curd, the curd should be treated as a uniform porous mass, not a particle surrounded by a relatively impervious skin.

Cheese was made by the direct acid set method in laboratory-size batches with careful control of processing variables. Total solids in unwashed curd increased linearly with heating time (between 20 and 142min) and temperature (between 42 and 64C). Total solids in unwashed and washed curd at a given heating temperature increased with heating rate (between .18 and .50 C/min). Heating rate influenced the relation between percent total solids in unwashed and washed curd. In comparison with a low heating rate (.18 C/min), higher heating rates (.30 and .50 C/min) yielded a firmer washed curd when the sample was taken at the same heating temperature and also with the same percent total solids, within ranges used commercially. Healing time (between 5 and 30min) and time of holding curd in whey (between 0 and 40min) at cooking temperature did not influence total solids of unwashed curd. Increasing the rate of agitation increased total solids in the curd, breakage of curd particles, and amount of sedimentable solids in the whey. Cooking conditions are critical in determining total solids in cottage cheese curd, and they influence other curd properties such as firmness and size distribution.

A procedure is described for gas liquid chromatographic determination of cis andtrans isomers of unsaturated fatty acids after fractionation of the saturated, monenoic, dienoic, and polyenoic fatty acid methyl esters by argentation thin layer chromatography. To test its reliability, the procedure was used for quantitative measurement of transisomers of unsaturated fatty acids in a known mixture of simple triglycerides containing saturated fatty acids from 4:0 to 24:0 andcis andtrans isomers of 14:1. 16:1, 18:1, and 18:2. Results of the analyses of five margarine and five butter samples are presented, together with results of infrared spectrophotometric analyses fortrans fatty acid concentrations, ultraviolet spectrophotometric analyses for conjugated fatty acid concentrations, and enzymatic analyses forcis-cis-methylene interrupted fatty acid concentrations. The combined argentation thin layer and gas Chromatographic procedure is suitable for determination of the principal fatty acids in complex food lipids such as milk fat.

Mixed diets containing 0 (control), 15 (medium fat), and 30% (high fat) of a protected tallow supplement (60% formylated soybean meal and 40% tallow) were fed to Holstein cows during the first 15 wk of lactation. Calculated energy densities of the diets were 1.85, 1.85, and 2.15 Mcal net energy lactation/kg dry matter. Dry matter intakes were higher on control and medium fat than on the high fat diet, but energy intakes were similar for all three diets. Treatments did not affect milk yield, but both diets containing protected tallow increased yields of fat and fat-corrected milk and energy efficiency, and decreased yields of solids-not-fat. Synthesis of fatty acid in the mammary gland was depressed 40 to 50% by protected tallow feeding. Transfers of dietary fatty acids to milk fat were about 35 and 25% from the medium fat and high fat diets. Concentrations of glucose in plasma were not affected by treatment. Non-esterified fatty acids, triglyceride, and cholesterol were elevated by protected tallow feeding.

Correct identification is one of the major problems facing those working with milk flavors. This committee sought first to develop a practical classification for off-flavors. Next, methods for producing some of the more common off-flavors were studied. Finally, a bibliography covering the literature from 1950 to 1976 on off-flavors was prepared. This report is intended to aid in training both research and quality control personnel in the hope that more uniform terminology will result.

The fatty acid composition of eight American, eight European, and four Japanese prepared infant formulas were determined and compared with fat sources listed on labels. Unsaturated fatty acids ranged from 20 to 83 per cent of the total. Generally, the fatty acid composition was consistent with the types of ingredients used; those with corn or soy oil had the highest levels of unsaturated fat, and those with milk fat the lowest; formulas of mixed composition fell in between. The formulas were compared with values for the fatty acid composition of human milk in the literature.