UTJECAJ GODIŠNJEG DOBA NA SASTAV MASNIH KISELINA I SADRŽAJ KONJUGACIJSKE LINOLNE KISELINE U MLIJEKU

The purpose of the research was to determine the fatty acid composition of milk of common breeds in Hungary that is Hungarian Simmenthal, Red Holstein Friesian and Black Holstein Friesian and the changes in the fatty acid composition of their milk fat throughout the year with special respect to the conjugated linoleic acid content. The amount of unsaturated fatty acids (oleic acid, linoleic acid and linolenic acid) including conjugated linoleic acid was higher in summer than in winter. In the case of the saturated fatty acids (butyric acid, caproic acid, caprylic acid, capric acid, myristic acid, palmitic acid and stearic acid) the opposite tendency was shown. The amount of conjugated linoleic acid ranged from 0.8 to 1.4%, with an average value of 1.1%.Svrha ovog istraživanja bila je odrediti sastav masnih kiselina u mlijeku glavnih pasmina u Mađarskoj, tj. mađarskog simentalca, crvenog holsteinfrizijca, i crnog holstein-frizijca, te promjene u sastavu masnih kiselina u njihovom mlijeku tijekom godine, osobito s obzirom na sadržaj konjugacijske linolne kiseline. Količina nezasićenih masnih kiselina (oleinska kiselina, linolna kiselina i linolenska kiselina) uključujući linolnu konjugacijsku kiselinu bila je veća ljeti nego zimi. U slučaju zasićenih masnih kiselina (maslačna kiselina, kaprinska kiselina, kaprilna kiselina, kapronska kiselina, miristinska kiselina, palmitinska kiselina, te stearinska kiselina) tendencija je bila suprotna. Količina konjugacijske linolne kiseline kretala se od 0,8 do 1,4% s prosječnom vrijednosti od 1,1%

A rapid and sensitive method for the determination of high-fructose corn syrup (HFCS) in honey

t

EFFECT OF MICROORGANISMS ON FREE AMINO ACID AND FREE D-AMINO ACID CONTENTS OF VARIOUS DAIRY PRODUCTS

Free amino acid and free D-amino acid contents of milk samples with different microorganism numbers and composition of dairy products produced from them were examined. Total microorganism number of milk samples examined varied from 1.25x106 to 2.95x106. It was established that concentration of both free D-amino acids and free L-amino acids increased with an increase in microorganism number. However, increase in D-amino acid contents was higher considering its proportion. There was a particularly significant growth in the microorganism number range from 1.5x106 to 2.9x106. Based on analysis of curds and cheese samples produced using different technologies we have come to the conclusion that for fresh dairy products and for those matured over a short time there was a close relation between total microorganism number and free D-amino acid and free L-amino acid contents. At the same time it was found that the ratio of the enantiomers was not affected by the total microorganism number. For dairy products, however, where amino acid production capability of the microbial cultures considerably exceeds, production of microorganisms originally present in the milk raw material, free amino acid contents of the milk product (both D- and L-enantiomers) seem to be independent of the composition of milk raw material

PROCJENA NEAKTIVNOSTI PROTUHRANJIVIH ČIMBENIKA OSJETLJIVIH NA TOPLINU U PUNOMASNOJ SOJI

The regular quality control on the adequacy of heat treatment of fullfat soybeans requires the application of rapid chemical methods. In the present work the trypsin inhibitor activity test and the urease test were applied on fullfat soya samples that were cooked in a pressured steam (toasted) or extruded at different temperatures and speed rates. In the case of toasting both of the results of the laboratory examinations proved that the heating was adequate, while in the case of the extruded samples the two tests gave different results. In the case of certain temperature and time combinations the more rapid and less accurate urease test claimed that the heat treatment reached the aim, while the results of the trypsin inhibitor activity test showed that the level of the inhibitors was still high and the fullfat soya was underheated.Redovita kontrola kakvoće primjerenosti toplinskog tretiranja punomasne soje zahtijeva primjenu brzih kemijskih metoda. U ovom radu primijenjeni su test aktivnosti inhibitora tripsina i test ureaze na uzorcima punomasne soje kuhane u pari pod pritiskom (tostirane) ili ekstrudirane na različitim temperaturama i brzinama. U slučaju tostiranja oba rezultata laboratorijskih ispitivanja su dokazala da je grijanje bilo primjereno, dok su u slučaju ekstrudiranja uzoraka oba testa dala različite rezultate. U slučaju određene temperature i vremenske kombinacije brzi i manje točan test ureaze potvrdio je da je toplinsko tretiranje postiglo svrhu dok su rezultati testa aktivnosti inhibitora tripsina pokazali da je razina inhibitora još uvijek visoka, a punomasna soja nedovoljno zagrijana

CHANGES IN FATTY ACID COMPOSITION OF DIFFERENT MILK PRODUCTS CAUSED BY DIFFERENT TECHNOLOGY

The fatty acid composition of cow’s milk with fat contents of 3.6%, Dalia cheese with fat contents of 44%, butter with fat contents of 80% and margarine with fat contents of 24% was determined after a heat treatment performed on cooking plate and microwave treatment, respectively of different durations. The biggest difference was obtained for oleic acid and elaidic acid since, with the exception of the margarine, in each case proportion of the cis-configurated oleic acid decreased while that of the trans-configurated elaidic acid increased. For all of the other fatty acids in the foodstuffs examined no such differences were obtained regarding change in fatty acid composition whose differences could influence healthy nutrition to considerable extent. Therefore we can take it as a fact that neither heat treatment performed on a traditional cooking plate nor microwave treatment affects considerably the composition of food fats

Hydrolysis of proteins performed at high temperatures and for short times with reduced racemization, in order to determine the enantiomers of D-and L-amino acids

Abstract. Racemization of free amino acids is considerably lower than that of amino acids bound in peptide. In the same experimental conditions, the rate of racemization of free amino acids is only 20-80% of that of peptide bound amino acids. When using to traditional protein hydrolysis, racemization was 1.2-1.6 times as high as that obtained at high temperatures (160-180 • C), under conditions ensuring total hydrolysis of the protein. This lower degree of racemization may be explained by the fact that, at high temperatures, the protein hydrolyses more rapidly into Key words and phrases: sample preparation; protein hydrolysis; racemization; amino acids, tryptophan, determination of D-amino acids 31 32 J. Csapó et al. free amino acids and the racemization of free amino acids is considerably slower that of amino acids bound in polypeptides. When hydrolysis is conducted at lower temperatures for longer times, the amino acids bound in the peptide chain are exposed for a longer time to the effects actually causing racemization. As a result, we may say that any factor which speeds up hydrolysis, will lower the degree of racemization. Racemization was higher for proteins in milk powder than for pure proteins. This may be explained by catalysis of racemization by the heavy metals present. After 48 hours at 110 • C and in presence of 4 M barium hydroxide, all amino acids (whether free or bound in peptide) totally racemized. Therefore the racemization of tryptophan cannot be determined using barium hydroxide promoted protein hydrolysis. High temperature hydrolysis (at 160 • C for 45 to 60 minutes, at 170 • C for 30-45 minutes and 180 • C for 30 minutes) are recommended for those who would like to hydrolyse the protein for short times and to determine the degree of racemization occurring in the polypeptide chain, but do not wish to use enzyme hydrolysis

Mineral content of three several muscles from six cattle genotypes

The aim of this study was to determine the effect of genotype and type of muscle on the mineral content of beef. Altogether 62 young bulls from Angus, Charolais, Holstein, Hungarian Simmental, Hungarian Grey, and Charolais×Hungarian Grey were used. The calcium content varied between 26–46 mg kg−1, in longissimus muscle of Hungarian Simmental it was significantly higher than for other genotypes except for Angus. Psoas major of Holstein had the highest phosphorus content, it significantly differed from the longissimus of Angus. Longissimus muscle of Angus was the poorest for magnesium, and the richest was the psoas major of Holstein and Hungarian Grey. Charolais had higher level of potassium in psoas major than Angus and Charolais×Hungarian Grey. Sodium content of semitendinosus in Charolais×Hungarian Grey was lower than in Holstein. Present data showed that levels were detected in the longissimus of Angus and semitendinosus of Holstein. Concerning zinc, a higher level was found in longissimus, especially for Holstein. The results confirmed that beef mineral content depends on genotype, and is related to muscle type, too

The free d-aspartic acid and d-glutamic acid content of sheep milk and sheep milk products

The role of D-amino acids of foods in the human health is a strongly discussed topic and usually, data came from the investigation of cow milk. We have studied the free D-aspartic acid and free D-glutamic acid content of sheep milk, heat-treated sheep milk at various temperatures and various products of sheep milk. Raw sheep milk didn’t contain free D-aspartic and D-glutamic acid in remarkable amount and ratio 5.92% free D-aspartic acid; 2.62% free D-glutamic acid). Our heat-treatments didn’t cause major change in the free D-aspartic and D-glutamic acid content (max.: 7.8% free D-aspartic acid; 5.3% free D-glutamic acid in total free aspartic and glutamic acid). Contrary, all of the investigated products contained high level of free D-amino acids. The free D-aspartic acid and free D-glutamic acid content of the products were 16,9-39,5%,and 13,3-27% in the percent of total free amino acids. The racemization of aspartic acid was higher, than that of glutamic acid in every product. The D-amino acid content of fermented milk products was higher than in different cheeses