Night milking adds value to cow's milk.

BACKGROUND: Melatonin is synthesized in greater concentration at night, and it plays an important role in sleep regulation. This study aimed to evaluate the melatonin concentration in milk collected by milking during the night and evaluates its effect, with or without tryptophan supplementation, in the sleep quality of adult Wistar rats. RESULTS: A difference (P < 0.05) was observed between the milking times, where the milk obtained at 02:00 presented a higher melatonin concentration (39.43 pg mL(-1) ) than that acquired at 15:00 (4.03 pg mL(-1) ). A biological assay was also performed on 32 male adult Wistar rats distributed among four groups (n = 8): those receiving an AIN-93M diet (control group) and three test groups [diets containing milk from milking at 02:00 (M2h ), milking at 15:00 (M15h ), and milking at 02:00 plus tryptophan supplementation (M2h T)] for 28 days. It was observed that the control group did not differ (P > 0.05) from the M15h group in terms of the levels of blood melatonin and urinary sulfatoxymelatonin, but differed from groups M2h and M2h T, whereas group M2h T presented higher blood melatonin and urinary sulfatoxymelatonin concentrations. CONCLUSION: Combining the techniques of night milking with tryptophan supplementation resulted in production of milk that improves sleep quality in rats.

Microcalorimetric study of adsorption of glycomacropeptide on anion-exchange chromatography adsorbent.

The adsorption of glycomacropeptide (GMP) from cheese whey on an anion-exchange adsorbent was investigated using isothermal titration microcalorimetry to measure thermodynamic information regarding such processes. Isotherms data were measured at temperatures of 25 and 45 degrees C, pH 8.2 and various ionic strengths (0-0.08 molL(-1) NaCl). The equilibrium data were fit using the Langmuir model and the process was observed to be reversible. Temperature was observed to positively affect the interaction of the protein and adsorbent. Microcalorimetric studies indicated endothermic adsorption enthalpy in all cases, except at 45 degrees C and 0.0 molL(-1) NaCl. The adsorption process was observed to be entropically driven at all conditions studied. It was concluded that the increase in entropy, attributed to the release of hydration waters as well as bounded ions from the adsorbent and protein surface due to interactions of the protein and adsorbent, was a major driving force for the adsorption of GMP on the anion-exchange adsorbent. These results could allow for design of more effective ion-exchange separation processes for proteins.

Hydrophobic interaction adsorption of whey proteins: effect of temperature and salt concentration and thermodynamic analysis.

The adsorptive behavior of bovine serum albumin (BSA) and beta-lactoglobulin (beta-lg) on hydrophobic adsorbent was studied at four temperatures and different salt concentrations. The Langmuir model was fitted by experimental equilibrium data showing that an increase in temperature and salt concentration results in an increase on the capacity factor of both proteins. A thermodynamic analysis coupled with isotherm measurements showed that salt concentration and temperature affected the enthalpic and entropic behavior of the adsorption process of both proteins, mainly to the beta-lg. The fast variation in the Z value for temperature over than 303.1K suggest a great conformational change occurring in the beta-lg structure, which almost duplicated the maximum adsorption capacity of this protein.

Caracterizaçäo da composiçäo de ácidos graxos de sucedâneos da manteiga de cacau / Characterization of fatty acid composition in cocoa butter replacements

Cocoa butter replacements are fats products used in total or partial substitution of cocoa butter in chocolates and chocolate products. Among the three cocoa butter kinds, lauric fat is incompatible with cocoa butter. Five brazilian and two imported cocoa butter replacements (CBR) were analysed by high resolution gas chromatography in order to determine the fatty acid composition. The objective of this work was to determine the kind of CBR. The results showed that three replacements were lauric fats with more than 40 per cent in lauric acid