Effect of process parameters on vitamins and sensory acceptability in micronutrient-fortified soymilk prepared by small-scale batch processing.

Effects of holding time before cooling, cooling method, and light or dark refrigerated storage on the stability of vitamin A, vitamin C, thiamine, riboflavin, and folate were investigated in fortified and unfortified soymilk. Vitamin C loss (6%) and mild vitamin A isomerization occurred when soymilk was held hot after fortification. Cooling bottled soymilk at ambient temperature or in an ice-water bath did not affect any vitamins. Loss of riboflavin (18%) and vitamin A isomerization occurred during 12 days of light-exposed refrigerated storage, in contrast to no vitamin degradation during dark refrigerated storage. A sensory panel of youth and children indicated no significant preferences between fortified and unfortified soymilk except for color, where the lighter-colored unfortified soymilk was preferred. Acceptable vitamin stability and sensory characteristics can be achieved in fortified soymilk produced in small-scale batch processes with appropriate management of production and storage conditions.

Metabolomics of acid whey derived from Greek yogurt.

Acid whey, a byproduct of Greek yogurt production, has little commercial value due to its low protein content and is also environmentally harmful when disposed of as waste. However, as a product of microbial fermentation, acid whey could be a rich source of beneficial metabolites associated with fermented foods. This study increases understanding of acid whey composition by providing a complete metabolomic profile of acid whey. Commercial and laboratory-made Greek yogurts, prepared with 3 different bacterial culture combinations, were evaluated. Samples of uncultured milk and cultured whey from each batch were analyzed. Ultra-high-performance liquid chromatography-tandem mass spectrometry metabolomics were used to separate and identify 477 metabolites. Compared with uncultured controls, acid whey from fermented yogurt showed decreases in some metabolites and increases in others, presumably due to the effects of microbial metabolism. Additional metabolites appeared in yogurt whey but not in the uncultured control. Therefore, the effect of microbial fermentation is complex, leading to increases or decreases in potentially bioactive bovine metabolites while generating new microbial compounds that may be beneficial. Metabolite production was significantly affected by combinations of culturing organisms and production location. Differences between laboratory-made and commercial samples could be caused by different starting ingredients, environmental factors, or both.

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.

Stability of key micronutrients added to fortified maize flours and corn meal.

Maize is a dietary staple in many countries. Although nutritious in many ways and a good source of energy, typical maize lacks several key micronutrients (MNs) that are often added to maize meals or flours to enhance nutritional value. Many factors affect MN stability in maize products, including uncontrolled conditions during distribution, long storage times, and MN premix composition. Consumer preparation also affects the final MN content of food. This review summarizes research relating to MN stability during processing, transport, storage, and meal preparation, focusing on those MNs most often added to maize and maize-based foods. Significant losses in B vitamins (B1, B2, B3, B6, B9, and B12) occur during manufacturing, distribution, and cooking. Added minerals (e.g., iron, zinc, calcium) are generally retained, although phytates in corn may affect bioavailability. Vitamins A and D3 are recent additions to fortification premixes for maize and are not well studied. Although there have been numerous studies of MN fortification in wheat flour, maize has not been as thoroughly examined, so recommendations are not as well supported. Future investigations should include well-designed and executed studies of the most labile MNs added to maize flours and meals, and their fate during all steps of processing, shipping, and preparation.

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.

Quality and sensory characteristics of hard red wheat after residential storage for up to 32 y.

Samples of hard red wheat packaged for long-term storage, ranging in age from 0 to 32 y, were obtained from donors in residential households. All samples had been stored under nonabusive conditions (7% to 10% moisture, 13 to 27 °C). Selected quality parameters of the wheat (moisture, thiamin, free fatty acids, flour extraction rate, bread loaf volume, and bread firmness) and sensory properties of bread made from the stored wheat (aroma, appearance, texture, flavor, overall liking, acceptance for use as part of the regular diet, and acceptance for use in emergency situations) were evaluated. Free fatty acids increased significantly from 0.897 to 11.8 µmol/g, and flour extraction rate decreased significantly from 76.5% to 69.9% over time. None of the other quality parameters measured (moisture, thiamin, bread loaf volume, and bread firmness) were significantly correlated with wheat storage time. Panelists who frequently or occasionally consume whole wheat bread rated all breads made from the stored wheat with hedonic scores (9-point scale) of at least 6.4 (like slightly to moderately). Consumer ratings of bread texture, flavor, and overall acceptability were negatively correlated with storage time (P < 0.001); however, at least 70% of panelists indicated that they would consume the bread as part of their regular diet even after 32 y of wheat storage, while over 97% would do so in an emergency. These data indicate that wheat maintains nutritional quality and makes acceptable bread when stored up to 32 y at 13 to 27 °C and 7% to 10% moisture. Practical Application: Wheat stored for the purposes of disaster relief has the potential of being stored for extremely long periods of time, which may result in undesirable changes in milling and baking quality. Therefore, we tested wheat that had been stored under residential conditions for up to 32 y to determine its functional quality and consumer acceptability. Our results indicate that wheat of low moisture (7% to 10%) packaged in sealed cans and stored for up to 32 y at or below typical room temperature retains quality and can be made into bread that is well accepted by consumers. Thus, whole wheat has good long-term storage stability and can be recommended for emergency food supplies.

Recommendations for optimization of fortified and blended food aid products from the United States.

Fortified blended foods (FBFs) were introduced into the Food for Peace program (also known as US Public Law 480) in the 1960s. Minimal changes have since been made to their formulations. A Food Aid Quality Enhancement Project to assess the nutritional adequacy of FBFs for vulnerable populations was conducted, and the findings indicate that FBFs do not meet the nutritional needs of infants and young children between the ages of 6 and 24 months. Improvements are also needed for FBFs intended for school-aged children and adults. Two separate products would better meet the varying nutritional needs of diverse groups of beneficiaries. Proposed here is a two-step strategy for better addressing the needs of today's food aid beneficiaries: 1) improving FBFs for general distribution to households, schools, and emergency settings, with potential efficiencies gained in manufacturing and formulation to reduce costs; 2) developing new products for infants and young children, which would deliver the nutrient density required for growth and development.

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.

Effect of preparation method on viscosity and energy density of fortified humanitarian food-aid commodities.

Corn soy blend, wheat soy blend, and corn soy milk are fortified food-aid commodities distributed by the US Government, and often used in complementary feeding programs. The viscosity and energy density of these products was compared in cooked porridges, at concentrations between 8% and 20% (w/w), using a Bostwick consistometer. All three products required nearly 20% addition of dry meal in water to achieve the energy density of 0.8 kcal/g, recommended for complementary foods. At this concentration, all three were excessively viscous. Cooking times beyond 1 min showed no significant increase in viscosity. Corn soy milk was less viscous than the other products at lower concentrations. Replacement of corn meal and soy with vegetable oil produces less viscous porridges but reformulation would be needed to maintain protein and micronutrient levels. Significant process and formulation changes are needed in these products to increase their suitability for use as complementary foods.

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.