Characterization of callase (β-1,3-d-glucanase) activity during microsporogenesis in the sterile anthers of Allium sativum L. and the fertile anthers of A. atropurpureum

We examined callase activity in anthers of sterile Allium sativum (garlic) and fertile Allium atropurpureum. In A. sativum, a species that produces sterile pollen and propagates only vegetatively, callase was extracted from the thick walls of A. sativum microspore tetrads exhibited maximum activity at pH 4.8, and the corresponding in vivo values ranged from 4.5 to 5.0. Once microspores were released, in vitro callase activity peaked at three distinct pH values, reflecting the presence of three callase isoforms. One isoform, which was previously identified in the tetrad stage, displayed maximum activity at pH 4.8, and the remaining two isoforms, which were novel, were most active at pH 6.0 and 7.3. The corresponding in vivo values ranged from pH 4.75 to 6.0. In contrast, in A. atropurpureum, a sexually propagating species, three callase isoforms, active at pH 4.8–5.2, 6.1, and 7.3, were identified in samples of microsporangia that had released their microspores. The corresponding in vivo value for this plant was 5.9. The callose wall persists around A. sativum meiotic cells, whereas only one callase isoform, with an optimum activity of pH 4.8, is active in the acidic environment of the microsporangium. However, this isoform is degraded when the pH rises to 6.0 and two other callase isoforms, maximally active at pH 6.0 and 7.3, appear. Thus, factors that alter the pH of the microsporangium may indirectly affect the male gametophyte development by modulating the activity of callase and thereby regulating the degradation of the callose wall

Biological Evaluation of the Protein Quality Sponge Guord (Luffa aegyptiaca) Seeds

Objectives: The study was aimed at investigating the bioavailability of the crude protein of Luffa aegyptiaca dehulled seeds in albino rats, with a view of utilizing it as a protein supplement for animals or livestock feeds. Materials and Methods: The rats were fed for 28 days with diet prepared with Luffa aegyptiaca dehulled seeds and casein served as the control. Clinical performance of the test animals was determined. The faecal and urinal Nitrogen content were recorded. The True Protein Digestibility (TD); Biological value (BV); Net Protein Utilization (NPU); Net Protein Retention (NPR); and Protein Efficiency Ratio (PER) were determined for the various diets used. Results: There was a significant difference (

Production and Evaluation of Ice Cream from Nigerian Tiger-Nut Milk Extract

Ice cream was prepared from water-soluble extracts of the yellow variety of Nigerian tiger-nut. A modified standard method was used for the production of the tiger-nut milk ice cream. The resulting ice cream had pH of 7.10, 35%Brix, specific gravity of 1.0888 and total solids of 45.67%. The proximate composition of the ice cream showed a crude protein content of 1.77 + 0.46%, fat 7.91 + 0.15%, carbohydrate content of 35.34 + 0.15% and a caloric value of 219.63 Kcal. These results are similar to the findings of Nawab (1991) on the quality standards for soy-ice cream. Sensory evaluation tests showed that the formulated ice cream from tiger-nut was acceptable. Microbiological examination showed that the tiger-nut ice cream was safe for consumption and an over-run of 55% was obtained in this study

Effects of submerged and anaerobic fermentations on cassava flour (Lafun)

Cassava tubers for processing into cassava flour, Lafun a Nigerian locally fermented product was subjected to two different types of fermentations: submerged and anaerobic fermentation for 72 h. Physicochemical changes that occurred during fermentation and their influence on the functional, rheological and sensory properties of the resulting flour were investigated. There was no significant difference in rate of decrease of pH and hydrocyanide under both fermentation conditions but titratable acidity differed significantly (p<0.05). Crude fibre, crude protein, ash, swelling index and final viscosity were significantly higher (p<0.05) in flour from submerged fermentation. Lafun from submerged fermentation had greater sensory quality and higher consumer preference than that of anaerobic fermentation. Key words: Cassava fermentation, physicochemical, functional, pasting properties

Mathematical Modelling of Thin Layer Dried Cashew Kernels

In this paper mathematical models describing thin layer drying of cashew kernels in a batch dryer were presented. The range of drying air  temperature was 70 – 110°C. The initial moisture content of the cashew kernels was 9.29% (d.b.) and the final moisture content was in the range of 3.5 to 4.6% dry-basis. Seven different thin layer mathematical drying models were compared according to their coefficients of determination (R2) mean square error (MSE) and mean relative deviation modulus (P) to estimate drying curves. The effects of the drying air temperature and time on the drying model constants and coefficients were predicted by multiple regression analysis using linear and non-linear type models. The results have shown that among the models, the Page model was found to be the best for describingthe drying behaviour of cashew kernels with R2, MSE and P values of 0.9830, 0.00311 and 5.046 respectively.Keywords: Modelling, cashew kernel, thin layer, drying, moisture loss

Effect of roasted bambara groundnut (voandzeia subterranea) fortification on quality and acceptability of biscuits

Biscuits were produced from refined wheat flour and roasted Bambara Groundnut (BGN) flour (140°C for 20 min) at ratio: 100:0, 80:20, 70:30, 60:40 and 50:50 respectively. The physical, chemical and organoleptic properties and acceptability of the biscuits were evaluated. The BGN fortified biscuits contained high quantities of crude protein (11.42-13.96%), total fat (14.30- 15.46%) and carbohydrate (64.85- 74.04%). The moisture content (3.42-3.74%) and the caloric value (451.94-454.38 kcal/100 gm) were similar in all the blends, while crude ash (0.56-2.13%) significantly (p<0.05) differed from each other. No significant difference (p>0.05) was observed between weight, thickness and spread ratio of the 100:0 wheat (control) and BGN fortified biscuits. However, there were significant differences (p<0.0.5) between the control and the fortified biscuits in breaking strength with the 100:0 ratio wheat flour biscuit having the higher value of 1.41. Sample with 50:50 ratio roasted BGN flour was significantly (p<0.05) darker in color than the control (100:0 wheat flour biscuit) and those fortified with 80:20 and 70:30 BGN flour. Sensory evaluation result indicates that all the fortified biscuits had high sensory ratings for the attributes evaluated. There were no significant (p>0.05) differences between biscuits with 80:20, 70:30 and 60:40 BGN flour and the control sample in crust color, crust surface characteristics and taste. Although, biscuits with ratio 50:50 BGN flour had lower mean scores in crumb color, texture and taste, they were generally acceptable to the panelist. In all, biscuits with up to 70:30 wheat flour/roasted BGN flour ratio blend compared favorably well with the control in all the evaluated quality attributes

Production and partial purification of glucoamylase from Aspergillus niger isolated from cassava peel soil in Nigeria

Glucoamylase is an enzyme that hydrolyses 1,4α and 1,6β-glucosidic linkages in polysaccharides yielding glucose. Aspergillus niger strains 1, 2 and 3 were locally isolated from cassava peel dumpsite for the production of glucoamylase enzyme. A. niger strains 1, 2 and 3 were screened for their hyper producing ability on potato dextrose agar using plate assay method fortified with starch agar, and showed zone of clearance of 17.0, 23.0 and 8.0 mm, respectively. The glucoamylase activity for A. niger strains 1 and 2 were 13 000.0 and 11 740.0, respectively. These values were however higher than the activity as obtained from the commercial enzyme with 2 500.0. Investigations on the protein (mg/ml), and specific activity (units/mg) on glucoamylase produced by A. niger strains 1 and 2 was 24.20, 537.19, 23.13 and 507.57, respectively. Fractionation of the enzyme ammonium sulphate (% w/v) using 60, 80 and 100% showed that the enzyme activities were 33 179.86, 47 985.86 and 19 167.65 units/ml, respectively. Protein concentrations were 16.29, 16.29 and 21.55 units/mg, respectively, while specific activities were 2 036.82, 2 945.725 and 889.45 units/mg, respectively. The production, packaging, and commercialization of glucoamylase in Nigeria will save a lot of foreign exchange earnings, and boost the economy of Nigeria.Keywords: Glucoamylase, specific activity, Aspergillus niger, fractionation, cassava peel.African Journal of Biotechnology, Vol 13(21) 2154-215