The aim of this research is to determine the bacteriological quality of the irrigation canal from Loskopdam, the two rivers that feed it and vegetables (broccoli and cauliflower) in Mpumalanga, South Africa and also to predict the presence of selected bacterial pathogens in irrigation water and on vegetables with logistic regression analysis. Water and vegetable samples were examined for the presence of total coliforms, faecal coliforms, Escherichia coli, Listeria monocytogenes, Salmonella sp., Enterococcus, Staphylococcus aureus, aerobic sporeformers, anaerobic sporeformers and aerobic colony counts were done. Apart from bacterial analysis, the following physico-chemical tests: temperature, pH, turbidity and COD were determined in water samples. The average COD and turbidity in the two rivers and the canal were higher than WHO and SA water guidelines. Sampling and analyses were done for a period of 12 months. Levels of faecal coliforms and E. coli were higher than the WHO standard. S. aureus, Intestinal Enterococci, Salmonella, L. monocytogenes were recovered from the two rivers and the canal. Apart from L. monocytogenes which was not recovered from cauliflower, all bacterial pathogens recovered from the surface water were recovered from the vegetables. 2Practical application: These results show that the rivers in Mpumalanga may contribute to the contamination in the irrigation canal which may be a possible preharvest source of contamination of broccoli and cauliflower, which may in turn constitute a health risk to consumers. Logistic regression analysis of the sampled data showed that COD was statistically reliable to predict L. monocytogenes, turbidity reliable to predict Intestinal Enterococci and faecal coliform and coliform reliable to predict Salmonella in irrigation water. Aerobic colony count (ACC) was statistically significant for the prediction of the three pathogens in vegetables.

In this study, the bambara protein isolate (BPI) was digested with three proteases (alcalase, trypsin and pepsin), to produce bambara protein hydrolysates (BPHs). These hydrolysates were passed through ultrafiltration membranes to obtain peptide fractions of different sizes (<1, 1-3, 3-5 and 5-10 kDa). The hydrolysates and their peptide fractions were investigated for antioxidant activities. The membrane fractions showed that peptides with sizes <3 kDa had significantly (p < 0.05) reduced surface hydrophobicity when compared with peptides >3 kDa. This is in agreement with the result obtained for the ferric reducing power, metal chelating and hydroxyl radical scavenging activities where higher molecular weight peptides exhibited better activity (p < 0.05) when compared to low molecular weight peptide fractions. However, for all the hydrolysates, the low molecular weight peptides were more effective diphenyl-1-picrylhydrazyl (DPPH) radical scavengers but not superoxide radicals when compared to the bigger peptides. In comparison with glutathione (GSH), BPHs and their membrane fractions had better (p < 0.05) reducing power and ability to chelate metal ions except for the pepsin hydrolysate and its membrane fractions that did not show any metal chelating activity. However, the 5-10 kDa pepsin hydrolysate peptide fractions had greater (88%) hydroxyl scavenging activity than GSH, alcalase and trypsin hydrolysates (82%). These findings show the potential use of BPHs and their peptide fraction as antioxidants in reducing food spoilage or management of oxidative stress-related metabolic disorders.

Summary Functional properties of protein concentrates prepared from three bambara groundnut landraces using acid precipitation and salt solubilisation methods were evaluated. The protein content of bambara grains (26–27%) was similar for the three landraces. The acid precipitation gave a much higher yield of protein concentrates (52%), which were also high in protein (79%) compared to the salt solubilisation method (yield: 25%, protein content: 57%). Functional properties of proteins were more influenced by the methods of preparation rather than the landraces. Protein concentrate prepared by salt solubilisation method showed higher emulsifying (63–66%), foaming (53–57%), water (1.4–2.0 mg mL−1) and oil absorption properties (2.2–2.6 mg mL−1) than the acid‐precipitated concentrates (53–57%, 63–66%, 2.0–2.7 mg mL−1, 1.4–1.7 mg mL−1). The foaming capacity and stability of all the protein concentrates decreased with increasing pH from 3 to 8. Salt solubilisation may be the most appropriate method for the enhanced functionality and utilisation of bambara groundnuts’ protein concentrates.

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Effects of frying treatments on texture (hardness) and colour parameters (L,a,b,ΔE) during deep fat frying of yellow fleshed cassava root slices (TMS 01/1371) were investigated. Slices (dimension of 40 mm × 25 mm × 3 mm) were divided into three portions and subjected to vacuum frying (fresh slices) and atmospheric frying (fresh and predried slices) and equivalent thermal driving forces (ETDF) of 60°C, 70°C, and 80°C were maintained during frying. The quality attributes investigated were best preserved in vacuum fried chips. The overall colour change in chips fried under vacuum conditions at 118°C and 8 min was the least (21.20) compared to fresh and atmospherically predried ones (16.69 and 14.81, resp.). A sharp reduction in the breaking force was obtained for all frying treatments after 8 min and this effect was the least in vacuum fried chips. First-order kinetics modeled the changes in quality attributes for all the temperatures investigated. Rate constants k (min−1) obtained for vacuum frying were almost equal to that of atmospheric frying while activation energies for hardness and colour change were 53.30 and 467.11 KJ/mol, respectively. Quality attributes studied were best preserved during vacuum frying.

Poly-γ-glutamic acid (γPGA) is a natural and promising biopolymer synthesized by Bacillus spp. during fermentation. This study isolated Bacillus spp. from ogi steep liquor (OSL) and lemon- ogi steep liquor (LOSL) using standard methods and determined the γPGA-producing ability. The antimicrobial and angiotensin-converting enzyme (ACE) inhibitory activities of γPGA polymer were evaluated and isolates were sequenced. Four isolates (TA004, TA006, TA011, TA012) selected based on phenotypic characterization and stickiness (<15 cm) showed antibacterial activity against different pathogens with the highest activity found in TA004 (22.5 mm) and least in TA011 (16.6 mm). Furthermore, time-kill assay showed that the combined γPGA polymer was more effective and demonstrated bactericidal activity over individual γPGA which are bacteriostatic in nature. All γPGA polymer exhibited ACE properties except TA011. The highest IC 50 was observed in TA006 (0.11 mg/ml) and least in TA004 (0.35 mg/ml). TA004 had the highest molecular weight (261 kDa) while TA011 had the least (194.97 kDa). In addition, all γPGA exhibited characteristic peaks at 3413–3268 cm -1 and 1722–1664 cm -1 that corresponded to amine N–H stretching intensities and C = O stretching in COOH. Bacillus isolates were identified as TA004 ( B. subtilis -GenBank: MH782061), TA006 ( B. amyloliquefaciens - GenBank: MH782075), TA011 ( B. subtilis - GenBank: MH782088), TA012 ( B. subtilis - GenBank: MH782083). OSL and LOSL have the potential for developing functional foods with a valuable effect on health.

Improvement of some quality attributes of soymilk through optimization of selected soybean sprouting parameters using response surface methodology, CyTA -Journal of Food, 16:1, 230-237, DOI: 10.1080/19476337.2017 To link to this article: https://doi.org/10. 1080/19476337.2017 ABSTRACTThis study aimed at producing functional soymilk by optimizing the sprouting conditions of soybeans using response surface methodology. Soaking (12-24 h) and germination times (48-96 h) were optimized using central complete randomized design. Responses obtained from experimental runs were fitted into second order polynomial regression model. Significance of model parameters was tested using ANOVA and R 2 was evaluated. The optimum sprouting conditions of soybeans were 12 h soaking and 52 h germination using desirability concept. Soymilk made from optimized conditions had 17% increase in total proteins, 50% reduction in phytic acid, 1.7% increase in total phenolics and a color change (ΔE) of 4.89 compared with the control. There was a significant reduction in trypsin inhibitor activity (0.03 mg/g TI), with increase in total amino acids and similar rheological properties in optimized soymilk. Optimized conditions obtained are adequate in the production of soymilk with improved nutritional and quality attributes.Mejoramiento de algunos atributos de calidad de la leche de soya [soja] a partir de la optimización de parámetros seleccionados de germinado de soya utilizando la metodología de superficies de respuesta RESUMEN El presente estudio se propuso producir leche de soya funcional a partir de la optimización de las condiciones de germinado de la soya, utilizando la metodología de superficies de respuesta. Con este objetivo se optimizaron la duración del remojo (12-24 h) y de la germinación (48-96 h) usando el diseño central completo aleatorizado. Las respuestas obtenidas en las pruebas experimentales fueron ajustadas al modelo de regresión polinomial de segundo orden. La significancia de los parámetros del modelo fue sometida a prueba, empleando ANOVA y evaluando R 2 . Partiendo del concepto de deseabilidad se determinó que las condiciones óptimas para el germinado de la soya son 12 h de remojo y 52 h de germinación. Se constató que en la leche de soya preparada bajo estas condiciones optimizadas se registró un aumento de 17% de proteínas totales, una reducción de 50% de ácido fítico, un aumento de 17% de fenólicos totales y un cambio de color de 4.89 en comparación con el control. Además, en la leche de soya optimizada se detectó una reducción significativa de la actividad inhibidora de la tripsina (0.03 mg/g TI), presentándose un incremento en los aminoácidos totales y que la misma exhibe propiedades reológicas similares. Las condiciones optimizadas logradas resultan adecuadas para la producción de leche de soya con atributos nutricionales y de calidad mejorados. ARTICLE HISTORY