Dynamic In Vitro Gastric Digestion of Sheep Milk: Influence of Homogenization and Heat Treatment

Milk is commonly exposed to processing including homogenization and thermal treatment before consumption, and this processing could have an impact on its digestion behavior in the stomach. In this study, we investigated the in vitro gastric digestion behavior of differently processed sheep milks. The samples were raw, pasteurized (75 °C/15 s), homogenized (200/20 bar at 65 °C)–pasteurized, and homogenized–heated (95 °C/5 min) milks. The digestion was performed using a dynamic in vitro gastric digestion system, the human gastric simulator with simulated gastric fluid without gastric lipase. The pH, structure, and composition of the milks in the stomach and the emptied digesta, and the rate of protein hydrolysis were examined. Curds formed from homogenized and heated milk had much looser and more fragmented structures than those formed from unhomogenized milk; this accelerated the curd breakdown, protein digestion and promoted the release of protein, fat, and calcium from the curds into the digesta. Coalescence and flocculation of fat globules were observed during gastric digestion, and most of the fat globules were incorporated into the emptied protein/peptide particles in the homogenized milks. The study provides a better understanding of the gastric emptying and digestion of processed sheep milk under in vitro gastric conditions.

No Glycation Required: Interference of Casein in AGE Receptor Binding Tests

For the determination of the binding of heated cow’s milk whey proteins such as β-lactoglobulin to the receptors expressed on immune cells, inhibition ELISA with the soluble form of the receptor for advanced glycation end products (sRAGE) and scavenger receptor class B (CD36) has been successfully used in the past. However, binding to heated and glycated caseins in this read-out system has not been tested. In this study, inhibition ELISA was applied to measure the binding of cow’s milk casein alone, as well as all milk proteins together, which underwent differential heat treatment, to sRAGE and CD36, and we compared those results to a dot blot read out. Moreover, binding to sRAGE and CD36 of differentially heated milk protein was measured before and after in vitro digestion. Casein showed binding to sRAGE and CD36, independent from the heat treatment, in ELISA, while the dot blot showed only binding to high-temperature-heated milk protein, indicating that the binding is not related to processing but to the physicochemical characteristics of the casein. This binding decreased after passage of casein through the intestinal phase.

The effect of antioxidants on xanthine oxidase activity in fresh ovine milk

In the present, the consequences of nitrate pollution of the environment are very pronounced. In humans and animals, microorganisms can reduce nitrates to nitrites, which cause cancer. Purified and homogeneous xanthine oxidase (XO) of cow's milk can restore these compounds, which makes the article extremely relevant. The purpose of the article is to determine the effect of antioxidants on the activity of xanthine oxidase in fresh ovine milk. Various natural and artificial antioxidants were examined for the detection of xanthine oxidase (XO) activity in ovine milk. Among the natural antioxidants, L-cysteine was more effective in the stabilization of XO in heated milk. XO of sheep milk activated by heat treatment in the presence of cysteine and molybdenum became able to convert nitrate and nitrite to nitric oxide (NO). Therefore, L-cysteine was used for double purposes: as the protector of enzyme active center against the oxidation during heat treatment of milk and as a reagent for S-nitrosothiol formation. Hypoxanthine, as a natural substrate of XO, is an effective electron donor for nitrate reductase (NR) and nitrite reductase (NiR) activities. Heat treatment of the milk in the presence of exogenous lecithin increased the activity of NR and NiR of XO and CysNO formation. Thus, during the heat treatment: a) excess of exogenous phospholipids disintegrates the structure of milk fat globule membrane (MFGM) and b) enzyme molecules denatured partially and their active center became available for exogenous cysteine, molybdenum, hypoxanthine, and nitrate or nitrite.

Whey as an indicator for standardizing cow’s milk fat percentage for cheese production

The dairy industry seems to have convinced the food industry that whey is a miracle product. The list of supposed benefits it gives to food is as long as your arm. Some of the benefits may be real. Whey is the liquid remaining after milk has been curdled and strained. It is a by-product of the manufacture of cheese or casein and has several commercial uses. To produce cheese, rennet or an edible acid is added to heated milk. This makes the milk coagulate or curdle, separating the milk solids (curds) from the liquid whey. Sweet whey is the byproduct of rennet-coagulated cheese and acid whey (also called sour whey) is the byproduct of acid-coagulated cheese. Sweet whey has a pH greater than or equal to 5.6, acid whey has a pH less than or equal to 5.1. Whey is also a great way to add sweetness to a product without having to list sugar as an ingredient as whey contains up to 75% lactose. And it sounds healthy. This study is done to research the examinations for the production of mozzarella cheese from Cow’s milk, after research and analyses of a physical-chemical peculiar feature of whey from coagulum. We have followed the processes from the drying of whey from the coagulum analyzer's physical-chemical peculiar feature. We carried out three experiments. For every experiment, we took three patterns and analyzed the physical-chemical. The calculation was appraised statistically. This paper deals with the research of% of whey fat during the process of milk production from standardized to non-standardized milk. Where% of whey fat should be an economic indicator for standardizing milk for dairy production.

Ovarian Index of KM Mice Influenced by Longer Term Consumption of Microwave-Heated Milk

ABSTRACT Microwave technology has been widely used in the food industry, but the effect of microwave-heated food on human health is being questioned. Female KM mice were chosen to be treated with microwave-heated milk (MM), and reproductive markers such as litter size, birth rate, survival rate, and ovarian index were evaluated. With longer term feeding, the reproductive status (body weight, birth rate, litter size, neonatal survival rate, interpregnancy interval, and brain superoxide dismutase and catalase activity) of KM mice treated with MM did not significantly change except for the ovarian index of first-generation mice, which was decreased significantly compared with the control group and the group given electrically heated milk. Longer term consumption of MM can affect the ovarian index of reproductive mice. HIGHLIGHTS