Biogenic Amines in Ground Beef in Relationship to Microbial Quality

Biogenic Amines in Ground Beef in Relationship to Microbial Quality

while the globulin mRNA constitutes only 25-30%. This mRNA was reverse transcribed and the complementary DNA was cloned at the Pst 1 site of plasmid p...

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while the globulin mRNA constitutes only 25-30%. This mRNA was reverse transcribed and the complementary DNA was cloned at the Pst 1 site of plasmid pBR322 in E. coli HBIOI host cells. This cloned cDNA was used to probe genomic DNA from other cereals and showed considerable homology. (Agric. Can. contract OSU 81-00411) EVALUATION OF UNDESIRABLE QUALITY CHARACTERISTICS OF QUEBEC WASHED POTATOES. Filadelfi*, Mary Ann, School of Food Science, Macdonald Campus of McGill University, Ste Anne de Bellevue, Quebec. Washed, poly-packed potato tubers, although essentially more appealing to the consumer, are potentially more susceptible to greening, increased glycoalkaloid content and infections due to the presence of bacteria and fungi. Simulated normal home storage (I to 4 weeks duration) of washed, non-washed poly, washed non-poly and nonwashed non-poly packaged potato tubers revealed severe bacterial and fungal growth as well as a high incidence of greening and sprouting in the washed poly-packed tubers. Although no high total glycoalkaloid (TGA) off-flavour was detected through oral sampling, confirmation using Soxhlell analysis of the TGA is still to be done. TGA SCREENING USING C J8 SEP-PAK CARTRIDGES. Filadelfi*, Mary Ann, School of Food Science, Macdonald Campus of McGill University, Ste Anne de Bellevue, Quebec. A C J8 Sep-Pak cartridge extraction method was developed to concentrate glycoalkaloids from potato tuber extracts. The modified alcoholic Soxhlell extraction method normally used for total glycoalkaloid (TGA) analysis was the control procedure. The newly developed C J8 Sep-Pak method was more rapid, simpler, safer and cheaper to run than the control method. Furthermore, it offered a high degree of reproducibility. FLAVOUR FINGERPRINTING BY HPLC. Pallon*, Kathleen and Mary Ann Filadelfi, School of Food Science, Macdonald Campus of McGiIl University, Ste Anne de Bellevue, Quebec. High performance liquid chromatography (HPLC) allows rapid quantitative analysis of subtle but distinct differences in flavour extracts. Preliminary comparison between a raspberry flavour extract prepared in our laboratory and a commercially available flavour extract was achieved through separation of a C J8 column using gradient mixtures of acetonitrile and water and a UV detector set at214 nm. Chromatograms revealed several peaks in common between the two extracts. Sensory differences in flavour and aroma were confirmed by the greater number and amplitude of peaks in chromatograms of the commercial extract. Tentative identification of individual peaks is now being done with a subsequent reevaluation of methodology to follow. BIOGENIC AMINES IN GROUND BEEF IN RELATIONSHIP TO Sayem, Nour and R. E. Simard, Departement de SCiences ettechnologie des aliments, Centre de Recherche en nutrition, Universite Laval, Quebec, Quebec. . The objective of this study was to assess the relationship of mono, d,- and polyamines to freshness of ground beef. Sixty-two samples of ground beef collected at random from retail outfits were analysed. The total microbial counts were measured and related to concentration profiles of eleven detected biogenic amines. The extraction method efficiency by puchlonc acid 0.6N for these amines was evaluated by cation exchan~e chromatography. Significant correlation between putrescine, cadavenne, spermidine and total microbial count was observed. These amines may be used as a potential indicator of quality in beef. MIC~OBlAL QUALITY.

STUDIES ON LIPOXYGENASE ACTIVITY OF FRENCH BEANS (Phaseolus vulgaris). Kermasha*, S. and M. Metche, Laboratoire de Biochimie Appliquee, Institut National Polytechnique de Lorraine, 54000 Nancy, France. School of Food Science, Macdonald Campus of McGill University, Ste Anne de Bellevue, Quebec*. French-bean Iipoxygenase were partially purified and the extraction procedure will be presented. The optimal pH for enzyme activity is ?2 and cyanide does not inhibit enzyme activity, in contrast to peroxIdase. French-bean lipoxygenase reacts with free unsaturated fally acids as well as with mono-, di- and triglycerides containing unsaturated fally aCids. However, overall the enzyme is more active with lineoleic acid than with glycerol esters, decreasing with: monolinoleine, dioleine and trilinoeline. Results show that lipoxygenase activity increases during French-bean storage at - 18° C and decreases in the dried seeds. Blanching causes complete inhibition to enzyme activity. Can. Inst. Food Sci. Technol. J. VoJ. 16, No. 3, 1983

STUDIES ON LIPASE ACTIVITY AND FATTY ACIDS DISTRIBUTION DURING FRENCH BEAN (Phaseolus vulgaris) SEED STORAGE. Kermasha*, S. and M. Metche, Laboratoire de Biochimie Appliquee, Institut national Polytechnique de Lorraine, 5400 Nancy, France. School of Food Science, Macdonald Campus of McGill University, Ste Anne de Bellevue, Quebec. Both Lipase activity and fally acid evolution were studied during French-bean seed storage. The extraction procedure for enzyme isolation is defined and the effect of pH and calcium on the enzyme activity will be presented. Lipolytic activity was characterized by the carboxylesterase nature of the enzyme. Temperature was found to be an important factor in the evolution of fally acid composition; results show no significant change during storage at - 18° C and 4° C. Conversely, there was a modification in the composition of fally acids at 20° C and 35° C; a significant decrease in the concentration of long chain fally acids with a concomitant increase in the concentration of shorter chain fally acids. INHIBITION OF AUTOXIDATION BY UNSAPONIFIABLE MATERIAL FROM SOME VEGETABLE SEEDS. Shihata, A.A., C.W. Nagel and A.R. McCurdy*', Department of Food Science and Technology, Washington State University. Department of Applied Microbiology and Food Science, University of Saskatchewan, Saskatoon, Saskatchewan S7N OWO. The unsaponifiable material from pumpkin, tomato, cantaloupe, lettuce and watermelon seeds was extracted and tested for antioxodant activity. The unsaponifiable material from all seeds was found to delay the oxidation of a Iineolic acid emulsion. Four separate components were isolated from the unsaponifiable material of wat.:rmelon, cantaloupe and lettuce seeds. Using HPLC, a component from both watermelon and cantaloupe unsaponifiable maller was shown to hav.: the same retention time as gamma tocopherol. A component from lelluce seed unsaponifiable material gave the same retention time as alpha tocopherol. The gamma tocopherol content, as determined by HPLC, of watermelon seeds was 42.3 mg/100 g unsaponifiable material and 6.4 mg/loo g of seeds and in cantaloupe seeds there was 31.1 mg/100 g unsaponifiable material and 4.7 mg/100 g seeds. Alpha tocopherol was found only in lelluce seeds (15.2 mg/loo g unsaponifiable material and 1.9 mglloo g seeds). TITRATION OF CHEESE WHEY. EFFECT OF DIPPING pH CONCENTRATION AND TITRANT ON FINAL pH. Hill*, A.R., D.M. Irvine and D.H. Bullock, Department of Food Science, University of Guelph, Guelph, Ontario. A factorial design was used to define final whey pH (pHf) as a function of dipping pH (pHd), level of concentration by reverse osmosis (C) and level of hydrochloric acid or sodium hydroxide (T). The equation indicated important interactions and was a reliable predictor of pHf for any combination of pHd, C and T (r = 0.99). Buffer maxima due to lactate and phosphate occurred at pH 3.8 and 5.5-7.0, respectively. The phosphate maxima varies with pHd and C. A transition between pHd and pHf changed from negative to positive. COMPARISON BETWEEN BAKER COMPRESSIMETER AND THE INTRUSION IN MEASURING BREAD FRESHNESS CONTAINING DIFFERENT SURFACTANTS. Kamel*, Basil S., J.R. Hoover and S. Wachnuik, Atkemix Inc., P.O. Box 1085, Brantford, Ontario. Bread freshness is one of the most critical factors upon which consumers base their rating and acceptance. The Baker Compressimeter is the only official AACC physical method used for measuring bread firmness. Instrumentation techniques for measuring rheological properties of food have increased significantly in recent years; the most widely used being the Instron Universal testing machine. The present study was designed to compare the results of the Baker Compressimeter and the Instron, and also to study the effect of different commercial surfactants on bread firmness. The levels of emulsifier used were 0,25 and 0.35% in white bread formula. Bread was stored at room temperalUre for 24, 96 and 168 h. Specific volume and firmness were determined. The correlation coefficient (R 2 ) between Baker Compressimeter and the Instron was 0.75. The Atmul P-32 was found to be superior to distilled monoglycerides in providing softer bread. COMPARATIVE STUDY OF SOME FACTORS AFFECTING LIPOLYSIS IN BUFFALOES, SHEEP AND COWS MILK. AI-

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