Kay H. McWatters

Efficacy of gaseous chlorine dioxide as a sanitizer for killing Salmonella, yeasts, and molds on blueberries, strawberries, and raspberries.

Gaseous chlorine dioxide (ClO2) was tested for its effectiveness in killing Salmonella, yeasts, and molds on blueberries, strawberries, and red raspberries. An inoculum (100 microl, 6.0 to 6.8 log CFU/g of fruit) that contained five serotypes of Salmonella enterica was deposited on the skin, calyx tissue, or stem scar tissue of blueberries, skin or stem scar tissue of strawberries, and skin of red raspberries, dried for 2 h at 22 degrees C, then held for 20 h at 4 degrees C and 2 h at 22 degrees C before treatment. Sachets that contained reactant chemicals were formulated to release gaseous ClO2 at concentrations of 4.1, 6.2, and 8.0 mg/ liter of air within treatment times of 30, 60, and 120 min, respectively, at 23 +/- 1 degrees C. Lethality of ClO2 to Salmonella, yeasts, and molds was measured when fruits were in an atmosphere that contained 75 to 90% relative humidity. Treatment with 8.0 mg/liter of ClO2 significantly (alpha = 0.05) reduced the population of Salmonella on blueberries by 2.4 to 3.7 log CFU/g. Lethality was higher to cells in inoculum placed on the skin compared with the stem scar tissue. Populations of Salmonella on strawberries treated with 8.0 mg/liter of ClO2 were reduced by 3.8 to 4.4 log CFU/g; a significant reduction of 1.5 log CFU/g of raspberries was achieved. Treatment with 4.1 to 8.0 mg/liter of ClO2 caused reductions in populations of yeast and molds on blueberries, strawberries, and raspberries of 1.4 to 2.5, 1.4 to 4.2, and 2.6 to 3.0 log CFU/g, respectively. Treatment with 4.1 mg/liter of ClO2 did not markedly affect the sensory quality of fruits stored for up to 10 days at 8 degrees C. Results indicate that gaseous ClO2 has promise as a sanitizer for small fruits.

Development of cowpea cultivars and germplasm by the Bean/Cowpea CRSP

This paper reviews accomplishments in cowpea cultivar and germplasm development by the Bean/Cowpea Collaborative Research Support Program (CRSP) which was funded by the United States Agency for International Development for a period of about 20 years. Drought-adapted, pest and disease resistant cultivars ‘Mouride’, ‘Melakh’ and ‘Ein El Gazal’ were developed for rainfed production in the tropical Sahelian zone of Africa. Cultivars ‘CRSP Niebe’ and ‘Lori Niebe’ which have seed and pod resistance to cowpea weevil and some disease resistance were developed for rainfed production in the tropical Savanna zone of West Africa. Cultivar ‘California Blackeye No. 27’ was developed for irrigated production in subtropical California, USA and is a semidwarf with heat tolerance and broad-based resistance to root-knot nematodes and Fusarium wilt. Various cultivars with persistent-green seed color including ‘Bettergreen’ and ‘Charleston Greenpack’ were bred for use in the food freezing industry in the USA. Germplasms were developed with unique traits including: snap-type pods, green manure/cover crop capabilities, heat tolerance during reproductive development, chilling tolerance during emergence, delayed leaf senescence as a mechanism of adaptation to mid-season drought and high grain yields, differences in stable carbon isotope discrimination, harvest index, rooting and plant water- and nutrient-relations traits, broad-based resistance to root-knot nematodes and Fusarium wilt, and resistance to flower thrips, cowpea aphid, lygus bug and cowpea weevil, and various quality traits including all-white and sweet grain. These germplasms provide a valuable resource for breeding additional cowpea cultivars for Africa and the USA.

Utilization of cowpeas for human food

Abstract This paper reviews the research and outreach accomplishments of the cowpea utilization project sponsored by the United States Agency for International Development-funded Bean/Cowpea Collaborative Research Support Program. Research has examined a limited number of cultivars and has taken as its starting point mature, dry seeds. A broad spectrum of food quality issues have been studied, including: • safety concerns and physiological effects associated with consuming legume seeds and products made from them; • chemical composition and nutritional quality of the seeds and products; • physical and functional behavior of seeds and products; and • socioeconomic aspects including sensory quality of seeds and products, consumer acceptance, and costs and impacts of technology adoption. Research foci have included: • The effect of pretreatment and storage on cowpea food quality; • processing whole seeds to improve food quality; • conversion of legume seeds into food ingredients, principally flours and meals; • processing seeds and ingredients to improve food quality; and • improvement of traditional foods and development of new foods from bean and cowpea-based ingredients.

Cowpea flour: A potential ingredient in food products

Cowpeas (Vigna unguiculata L. Walp) are an important grain legume in East and West African countries as well as in other developing countries. The U.S. is the only developed country producing large amounts of cowpeas. High protein (18 to 35%) and carbohydrate (50 to 65%) contents, together with an amino acid pattern complementary to that of cereal grains, make cowpeas potentially important to the human diet from a nutritional standpoint. Despite their potential as an inexpensive source of protein and energy, cowpeas are underutilized in the U.S. and other industrialized countries. A simple technology for preparing cowpea flour would stimulate increased consumption of this legume. This paper reviews the status of cowpea flour production technologies and uses of cowpea flour in various food products.

Consumer acceptance of fresh-cut iceberg lettuce treated with 2% hydrogen peroxide and mild heat.

An antibacterial treatment consisting of 2% hydrogen peroxide at 50 degrees C for 60 s was evaluated for its effects on the sensory quality of fresh-cut iceberg lettuce. Treated lettuce was packaged in polyethylene film by a protocol used in the fresh-cut produce industry and then stored along with untreated controls for 3, 10, and 15 days at 5 degrees C. Gas chromatographic analysis confirmed that the desired initial volume (approximately 6 liters) and oxygen gas content (approximately 10%) were maintained during storage. Consumers from the local community who were the primary shoppers for their households and who purchased and ate lettuce regularly evaluated the appearance, color, aroma, flavor, and texture of the lettuce and their overall liking of the lettuce. Forty consumers were recruited to evaluate processing replication 1 on 26 April, and another 40 were chosen to evaluate processing replication 2 on 3 May. Because replication differences were observed in instrumental color measurements and in mean sensory ratings, replications were not pooled for the two test dates. Lettuce purchased for processing replication 2 was considerably greener than that used in replication 1. Overall, the antibacterial treatment was more effective than the control treatment in maintaining sensory quality over 15 days of storage, provided that the lettuce was initially intensely green. Three-fourths of the participants indicated that they would be willing to buy precut packaged lettuce that had already been treated at the packinghouse or processing plant with an antibacterial solution, and of these participants, 62.5% indicated that they would be willing to pay 5 to 10 cents more per bag.

Functional characteristics of cowpea (Vigna unguiculata) flour and starch as affected by soaking, boiling, and fungal fermentation before milling

Abstract Functional characteristics of cowpea flour and starch as affected by soaking, soaking and boiling (S/B), and fermentation of seeds with Rhizopus microsporus var. oligosporus before milling were investigated. Soaking and fungal fermentation had fewer effects on flour and starch functionality compared to boiling. Boiling drastically reduced foamability and thus increased specific gravity of whipped cowpea paste. The gradual increase in total color differences of pastes prepared from S/B seeds with or without fermentation was due to a gradual decrease in lightness (L∗). The more intense yellow color observed in whipped pastes from S/B seeds after fermentation was due to increased b∗ and decreased L∗ values. Starch from all treatments had greater swelling volume than flour. Significant reductions in swelling volume of flour and starch were due to the boiling treatment. Pasting characteristics of control flour and starch are concentration dependent. The pasting curve pattern of cowpea flour differed markedly from that of cowpea starch.

Quality characteristics of ground beef patties extended with moist-heated and unheated seed meals

Extending ground beef with 5% peanut, soybean, pecan, or field pea meals increased cooked yields and water-retention properties of beef patties. Extended patties were more tender, requiring less force to compress than all-beef patties. Protein content was significantly increased by the addition of peanut and soybean meal to ground beef. Unheated meals produced patties with larger volumes but were poorer in aroma and flavor qualities than all-beef patties or those prepared with heated meals. Moist heat effectively improved aroma and flavor qualities of the meals without altering their binding properties.

Functional characteristics of cowpea flours in foods

Functionality of legume flours as food ingredients is influenced by genetic and agronomic factors, storage, composition and processing. The processing of flour from dry cowpeas (Vigna unguiculata) is a simpler technology than that utilized for oilseed flour production. A defatting step is not required because the crude fat content of cowpeas is low (∼1–2%); however, decortication (seed coat removal) is necessary if a light-colored flour is to be obtained from cultivars with dark testa or eyes. Process condition employed in the decortication of cowpeas and production of cowpea flour influence the quality of subsequent products made from the flour. Functionality of cowpea flour as an ingredient in wheat flour mixtures, akara and moin-moin (fried and steamed cowpea paste, respectively), extruded products and meat products will be reviewed.

NUTRITION CONSIDERATIONS IN FOOD SELECTION

The importance of nutrition consideration to households in food selection is instrumental in the development of information programs to promote public health and to market healthy food. Using a national telephone survey of 2880 U.S. households, this study examines the role and influence of socio-economic characteristics and lifestyle on a household meal planners consideration of four dietary components in food selection. Household income, children in households, geographic location, and gender, age, education, and lifestyle of meal planners affected the consideration of dietary components in food selection. The results provide a basis for developing education programs that focus on the particular dietary considerations of identified demographic subgroups.

Changes in fatty acid, simple sugar, and oligosaccharide content of cowpea (Vigna unguiculata) flour as a result of soaking, boiling, and fermentation with Rhizopus microsporus var. oligosporus

Changes in fatty acid, simple sugar, and oligosaccharide content of cowpea flour as a result of soaking, boiling, and fermentation with Rhizopus microsporus var. oligosporus were investigated. The major fatty acids in flour made from both nonfermented and fermented cowpeas were linoleic, palmitic, and linolenic. With the exception of lower amounts of lauric, palmitic, linoleic, and linolenic acids and slightly higher amounts of lignoceric acid, the remaining fatty acids in flour made from soaked cowpeas were essentially unchanged from the control flour made from cowpeas that were not soaked, boiled or fermented. Soaking followed by boiling generally increased amounts of fatty acids in flour compared to the control. Rhizopus microsporus did not utilize lipid during 24 h of fermentation. Soaking decreased the amount of sucrose and stachyose by 39% and 18.4%, respectively, whereas soaking followed by boiling caused decreases of 58.3% and 49.3%. Complete elimination of sucrose, raffinose, and stachyose was achieved after 15 h of fermentation.