Canadian Institute of Food Technology Journal最新文献

One hundred and twenty-five imitation dairy toppings and forty real dairy toppings were examined for total place psychrotrophic, coliform and enterococci counts, and for the incidence of staphylococci and salmonellae. All samples were free of salmonellae and coagulase positive staphylococci. Five (3.03%) of the 165 samples had a total plate count of > 1000/ g. The psychrotrophic count for all samples averaged < 10/ g. Twelve percent of the samples were contaminated with eoliforms and 11.5% with enterococci. A comparison of aerosol containers of imitation dairy topping revealed that 5.0% of the imitation dairy topping samples were coliform positive as opposed to 0.0% of the real dairy toppings. In addition 30% of the imitation samples contained enterococci as compared to 7.5% of the samples of real dairy topping. The total plate counts and psychrotrophic counts for these products were similar.

Coefficients of transpiration of five varieties of potatoes, three varieties of onions, two varieties of cabbage and carrofe and one variety of parsnips and rutabagas (turnips) were determined under conditions similar to those in ordinary refrigerated storage. Average values of the coefficient of transpiration could be grouped into three broad ranges: high (500-850 mg/(kg, hr, mm Hg); carrots and parsnins), intermediate (100-250; cabbage and rutabagas) and low (10-80; potatoes and onions).

The inhibitory effect of sodium nitrite on the outgrowth of spores of Clostridium botulinum 13983B was studied in various bacteriological media and meat suspensions. The media and meat suspensions were adjusted to pH 6.2 and heated in the presence of nitrite at 110°C for 20 min. Perigo factor was produced in Perigo-type medium (PT) and Reinforced Clostridial Medium (RCM) when heated with 20 ppm of nitrite, but not in Liver Veal Medium (LVM) and Wynne Fluid Medium (WFM) even when heated with 100 ppm of nitrite. Suspensions of 50% meat in water, prepared from under-process, normal-process and over-process meats, required 500 ppm, 150 ppm and 50 ppm of nitrite, respectively, for inhibition of outgrowth.

Dialysis removed the inhibitory activity from two of the bacteriological media (LVM and WFM) and from all meat suspensions, but not from PT and RCM media. The residual nitrite concentrations were approximately the same in all seven heated preparation (100 ppm added before heating), but the redox potential varied considerably among them. The addition of reducing agents to meat suspensions decreased the redox potential and increased the inhibitory activity but did not induce the formation of the Ferigo factor.

The light and dark muscle of Atlantic spring mackerel differed sharply in lipid content, the dark muscle showing about 12% in spring males and 9% in females as against values of 2-3% for light flesh from both sexes. Fall mackerel had nearly twice as much fat in the dark muscle and three times as much in the light muscle. The fatty acid compositions of the total lipids of different muscle samples from three lots of fish and of triglycerides and phospholipids from muscles of another lot of fish are compared.

A routine method based on measurement of (post-mortem conversion of adenosine nucleotides to inosinic acid was developed for following the onset of rigor mortis in beef and chicken muscles. Conversion of adenosine nucleotides to inosinic acid was accompanied by a decrease in absorbance at 258 mμ and an increase at 250 mμ.The ratio of the two absorbance measurements changed linearly with the ratio of adenosine nucleotides and inosinic acid. Immediately after slaughter, the absorbance ratio was about 1.2 in both beef and poultry muscles, but gradually dropped to a value of 0.84–0.89 during the onset of rigor mortis as determined by isometric tension development. This value of the absorbance ratio at rigor was confirmed also by comparison with phosphate ester, adenosine triphosphate, and shear force measurements. Besides being simple and rapid, the method is accurate since it indicates indirectly the adenosine triphosphate content of the muscle tissue, the determining factor in rigor mortis.