Gamma irradiation of cowpea (Vigna unguiculata L. Walp) flours and pastes: Effects on functional,thermal and molecular properties of isolated proteins

In a previous study irradiation of cowpea flours and pastes at medium (10 kGy) and high (50 kGy) doses resulted in significant changes in protein-related functional properties. To understand some of the effects of gamma irradiation on cowpea proteins in particular, we isolated proteins from cowpea flours (FPC) and pastes (PPC) treated with gamma irradiation at 2, 10, and 50 kGy and analyzed their functional, thermal and molecular properties. Nitrogen solubility index of both FPC and PPC decreased, whereas oil absorption and emulsion capacities increased significantly with increasing irradiation dose. Differential scanning calorimetry showed decreases in transition temperatures (T_d) and enthalpies (ΔH), indicating a progressive denaturation of cowpea proteins with increasing irradiation. Size exclusion HPLC revealed increases in protein molecular weights, probably due to protein–protein cross-linking with irradiation in a dose-dependent manner. Reducing SDS-PAGE of FPC and PPC samples seems to suggest that the contribution of disulphide bonds to irradiation-induced cowpea protein–protein cross-linking is small.     

Effect of fruit ripeness and method of fruit drying on the extractability of avocado oil with hexane and supercritical carbon dioxide

BACKGROUND: Oil yield from avocado fruit may be influenced by fruit pre‐treatment and extraction method. Unripe and ripe avocado fruit pieces were deep‐frozen at ? 20 °C and either freeze‐dried or oven‐dried (80 °C). Oil yield from these samples was determined after extraction with hexane and supercritical carbon dioxide (SC‐CO₂). The fruit samples were examined using scanning electron microscopy before and after oil extraction. RESULTS: Average oil yield from ripe fruit (freeze‐dried and oven‐dried combined) was 72 g kg^?1 higher than from unripe fruit for SC‐CO₂ extracts and 61 g kg^?1 higher for hexane extracts. This may be due to enzymatic degradation of parenchyma cell walls during ripening, thus making the oil more available for extraction. Freeze‐dried samples had a mean oil yield 55 g kg^?1 greater than oven‐dried samples for SC‐CO₂ extracts and 31 g kg^?1 higher for hexane extracts. However, oil yields from ripe fruit (freeze‐dried and oven‐dried) subjected to hexane extraction were not significantly different. All hexane extracts combined had a mean oil yield 93 g kg^?1 higher than SC‐CO₂ extracts. CONCLUSION: SC‐CO₂ may be more selective and may create paths of least resistance through the plant material. Hexane, on the other hand, is less selective and permeates the whole plant material, leading to more complete extraction and higher oil yields under the experimental conditions. Copyright © 2007 Society of Chemical Industry     

Effects of different souring methods on the protein quality and iron and zinc bioaccessibilities of non-alcoholic beverages from sorghum and amaranth

Souring by lactic acid fermentation and lactic acid acidification as well as inclusion of amaranth were explored as ways of improving the protein quality and iron and zinc bioaccessibilities of non-alcoholic sorghum-based beverages. The bioaccessible iron and zinc increased by 128–372%, 24–194%, respectively, in the fermented and chemically acidified beverages compared to the beverages without fermentation or acidification. The protein digestibility, reactive lysine, and bioaccessible iron in sorghum-amaranth beverages increased by 14–58%, 24–52% and 34–64%, respectively, compared with the 100% sorghum beverages. Both fermentation and acidification with lactic acid have the potentials for improving the nutritional quality of cereal-based foods as a means of combating protein malnutrition and iron and zinc deficiencies.     

Aqueous Extraction of Coconut Oil by an Enzyme-Assisted Process

A pre-extraction enzyme treatment of copra meal was incorporated into a rural wet copra oil extraction process to investigate the possibility of improving the traditional process by the enzyme treatment. The enzymes used in the study were combinations of a protease from Aspergillus niger, a cellulase/hemicellulase preparation from Trichoderma reseei, and α-amylase from A oryzae and a pectinase from A niger (all were crude preparations). Finely milled copra meal samples were mixed with water and the enzymes and incubated at 37°C for 6 h or more. After the treatment, the meal was extracted using a water flotation technique. Yield increases of about 50%, relative to experimental controls, were observed, suggesting the possibility of using the enzyme-assisted oil extraction methods to improve upon traditional copra processing. © 1997 SCI.     

Online Genetic Improvement on the java virtual machine with ECSELR

Online Genetic Improvement embeds the ability to evolve and adapt inside a target software system enabling it to improve at runtime without any external dependencies or human intervention. We recently developed a general purpose tool enabling Online Genetic Improvement in software systems running on the java virtual machine. This tool, dubbed ECSELR, is embedded inside extant software systems at runtime, enabling such systems to self-improve and adapt autonomously online. We present this tool, describing its architecture and focusing on its design choices and possible uses.     

Microbial modification of the texture of grated cassava during fermentation into akyeke

The traditional akyeke inoculum and fermenting akyeke, an indigenous cassava product, were investigated to identify microbial species responsible for the modification of cassava texture during fermentation. Both field and laboratory samples were examined and only some cultures isolated on Plate Count Agar and Malt Extract Agar were found to be capable of causing a softening of cassava tissue when plated directly on sterile cassava slices. The cassava tissue softening isolates on PCA were tentatively identified as Bacillus subtilis and isolates on MEA as Candida tropicalis and Zygosacchromyces florentinus. The population of B. subtilis in the laboratory sample of inoculum was found to be 2.4 x 10(9) cfu g(-1) and increased during dough fermentation from 1.1 x 10(7) to 3.5 x 10(9) cfu g(-1) after 96 h. C. tropicalis was present in the inoclum at 3.0 x 10(9) cfu g(-1) and increased during dough fermentation from 3.2 x 10(6) to 6.9 x 10(7) cfu g(-1) whilst Z. florentinus was present in the inoclum at 9.1 x 10(8) cfu g(-1) and increased from 8.1 x 10(5) to 7.5 x 10(6) cfu g(-1) during dough fermentation.     

Effects of processing sorghum and millets on their phenolic phytochemicals and the implications of this to the health‐enhancing properties of sorghum and millet food and beverage products

Sorghum and millet grains are generally rich in phytochemicals, particularly various types of phenolics. However, the types and amounts vary greatly between and within species. The food‐processing operations applied to these grains, i.e. dehulling and decortication, malting, fermentation and thermal processing, dramatically affect the quantity of phenolics present, most generally reducing them. Thus the levels of phytochemicals in sorghum and millet foods and beverages are usually considerably lower than in the grains. Notwithstanding this, there is considerable evidence that sorghum and millet foods and beverages have important functional and health‐promoting effects, specifically antidiabetic, cardiovascular disease and cancer prevention, due to the actions of these phytochemicals. Also their lactic acid bacteria‐fermented products may have probiotic effects related to their unique microflora. However, direct proof of these health‐enhancing effects is lacking as most studies have been carried out on the grains or grain extracts and not the food and beverage products themselves, and also most research work has been in vitro or ex vivo and not in vivo. To provide the required evidence, better designed studies are needed. The sorghum and millet products should be fully characterised, especially their phytochemical composition. Most importantly, well‐controlled human clinical studies and intervention trials are required. © 2014 Society of Chemical Industry