Inhibition of Clostridium perfringens Growth during Extended Cooling of Cooked Uncured Roast Turkey and Roast Beef Using a Concentrated Buffered Vinegar Product and a Buffered Vinegar Product.

This research was conducted to evaluate the effectiveness of a concentrated buffered vinegar product (CBV) and a simple buffered vinegar product (BV) for controlling Clostridium perfringens outgrowth during extended cooling times of ready-to-eat roast turkey and roast beef. Whole turkey breasts and beef inside rounds were injected with a typical brine and then ground and mixed with CBV (0.0, 2.01, 2.70, and 3.30% [w/w]) or BV (0.0, 1.75, 2.25, and 3.75% [w/w]) and a three-strain C. perfringens spore cocktail to a detectable level of ca. 2 to 3 log CFU/g. The meat was divided into 10-g portions, vacuum packaged, and stored frozen until tested. The turkey and beef were cooked in a programmable water bath to 71.6°C (160.8°F) in 5 h and to 57.2°C (135°F) in 6 h, respectively. The cooked turkey and beef were then cooled exponentially from 48.9 to 12.8°C (120 and 55°F) in 6, 9, 12, 15, and 18 h for the five cooling treatments. The cooling continued until the temperature reached 4.4°C (40°F). C. perfringens counts were determined at 54.4°C (130°F) and 4.4°C. CBV at 2.01% effectively limited C. perfringens growth in turkey to ≤1 log CFU/g with up to a 9-h cooling treatment, and 2.70 and 3.30% solutions were effective with up to the 18-h cooling treatment. BV had an inhibitory effect on C. perfringens outgrowth in beef but did not limit growth to ≤1 log CFU/g at any concentration tested for any of the cooling treatments.

Isolation and characterization of the microflora of nixtamalized corn masa.

Corn tortillas are a staple in the diet among the Mexican population, and are traditionally produced through a process known as nixtamalization. This traditional process involves steeping whole-kernel corn in an alkaline solution overnight and then grinding the corn into dough (masa), which is then baked. While the masa is held before baking, significant microbial change can occur which leads to fermentation and spoilage. The objective of this research was to characterize and identify the microflora of nixtamalized corn masa from six different commercial tortilla mills throughout Guadalajara, Mexico. The identification of samples was conducted using the microbial identification system (MIS), which analyzes cellular fatty acids via gas chromatography to identify bacterial species. Lactic acid bacteria and aerobic mesophiles were the predominant organisms, with both groups having counts ranging from 10(4) to 10(7)cfu/g across all mills. Coliform populations were observed at counts of 10(2) to 10(3)cfu/g, while yeast and mold counts were typically less than 10(1)cfu/g. Some mills showed no presence of coliforms or yeast or mold. Streptococcus bovis and Lactobacillus oris were isolated from all mills, and were the most prevalent organisms representing 43% and 17% of all lactic acid bacteria isolated, respectively. S. bovis was also isolated on the aerobic tryptic soy plates and was the most prevalent species representing 19% of the total organisms from these aerobic plates.

Translocation and cross-contamination of E. coli O157 in beef eye-of-round subprimal cuts processed with high-pressure needleless injection.

UNLABELLED: High-pressure needleless injection (HPNI) is an emerging enhancing process where small-diameter, high-velocity bursts of liquid penetrate soft foods at pressures up to 69 MPa. The incidence and depth of translocated surface-inoculated E. coli O157 in HPNI-processed beef eye-of-round subprimal cuts was determined. HPNI translocated E. coli O157 from the surface to the interior of the eye-of-round subprimal cuts with incidence of 40% (± 7%), 25% (± 8%), and 25% (± 8)% for subprimals that had been surface-inoculated with a 4-strain cocktail at 0.5, 1, and 2 log10 CFU/cm² , respectively. The run-off water was collected and found to contain 2, 2, and 3 log10 CFU/mL E. coli O157. The runoff was reused for HPNI of additional subprimals, and this resulted in a cross-contamination incidence of 83% (± 4%), 60% (± 15%), and 37% (± 6)%. Incidence of translocation and cross-contamination was similar at 0 to 1, 1 to 2, 2 to 3, 3 to 4, 4 to 6, and 6 to 8 cm below the inoculated surface. Results indicate that surface microbiota on beef will be carried to the interior of HPNI-processed beef by initial translocation from the surface with the injected fluid and by cross-contamination with recycled fluid. PRACTICAL APPLICATION: This research has practical relevance for the beef enhancement process called high-pressure needleless injection. The process's effect on surface bacteria on beef was studied.

Sensitivity comparison of sequential monadic and side-by-side presentation protocols in affective consumer testing.

The relative sensitivity of side-by-side and sequential monadic consumer liking protocols was compared. In the side-by-side evaluation, all samples were presented at once and evaluated together 1 characteristic at a time. In the sequential monadic evaluation, 1 sample was presented and evaluated on all characteristics, then returned before panelists received and evaluated another sample. Evaluations were conducted on orange juice, frankfurters, canned chili, potato chips, and applesauce. Five commercial brands, having a broad quality range, were selected as samples for each product category to assure a wide array of consumer liking scores. Without their knowledge, panelists rated the same 5 retail brands by 1 protocol and then 3 wk later by the other protocol. For 3 of the products, both protocols yielded the same order of overall liking. Slight differences in order of overall liking for the other 2 products were not significant. Of the 50 pairwise overall liking comparisons, 44 were in agreement. The different results obtained by the 2 protocols in order of liking and significance of paired comparisons were due to the experimental variation and differences in sensitivity. Hedonic liking scores were subjected to statistical power analyses and used to calculate minimum number of panelists required to achieve varying degrees of sensitivity when using side-by-side and sequential monadic protocols. In most cases, the side-by-side protocol was more sensitive, thus providing the same information with fewer panelists. Side-by-side protocol was less sensitive in cases where sensory fatigue was a factor.

Storage, preparation, and usage of fortified food aid among Guatemalan, Ugandan, and Malawian beneficiaries: a field study report.

BACKGROUND: An important consideration in determining the ability of fortified food-aid commodities to meet the nutritional needs of beneficiaries is the manner in which commodities are utilized and prepared and the degree to which micronutrient losses occur during handling and cooking by the beneficiaries. OBJECTIVE: A field study was conducted in Uganda, Malawi, and Guatemala to obtain data on storage, preparation, and usage of fortified blended foods provided by the US Agency for International Development. METHODS: Interview and observational data on the use of corn-soy blend, cornmeal, soy-fortified cornmeal, soy-fortified bulgur, and fortified vegetable oil were collected from more than 100 households and two wet-feeding sites (where food is prepared and served by staff on-site) in 32 villages. RESULTS: Storage practices by beneficiaries appeared to be appropriate, and all commodities observed were free from off-flavors and odors. Cooking water was typically obtained from boreholes or open wells with a pH range of 4.7 to 7.7 Food preparation usually took place in covered areas with the use of an aluminum or clay pot over a wood-fueled fire. Thin or thick porridges were the most common dishes prepared from cereal-based products, with concentration ranges of 10% to 31% (wt/ wt) in water. Cooking times for porridges ranged from 5 to 53 minutes, with a mean of 26 minutes. Tortillas and beverages were other preparations commonly observed in Guatemala. Vegetable oil was typically used for pan frying. CONCLUSIONS: Cooking fuel could be saved and nutritional quality probably improved if relief agencies emphasized shorter cooking times. These data can be used to simulate preparation methods in the laboratory for assessment of the nutritional impact of cooking.