Optimization of microwave drying conditions of two banana varieties using response surface methodology

AbstractOptimization of microwave drying conditions of Luvhele and Mabonde banana varieties were studied using response surface methodology. The drying was performed using a central composite rotatable design for two variables: microwave power level (100, 200 and 300 W) and drying time (40, 26, and 12 min.) for Luvhele; (100, 200 and 300 W) and (42, 27, and 12 min) for Mabonde. The colour and texture (hardness) data were analyzed using ANOVA and regression analysis. The fitness of the models obtained was good as the lack of fit for each of the models was not significant. The coefficient of determination R2 of the models was relatively high, hence the models obtained for the responses were adequate and acceptable. Drying conditions of 178.76 W, 12 min. drying time were found optimum for product quality at a desirability of 0.91 for Luvhele; while 127.67 W, 12 min. with a desirability of 0.86 was predicted for Mabonde. The result of this study could be used as a standard for microwave processing of Luvhele and Mabondebanana varieties.

The effect of different concentrations of pre-harvest gibberellic acid on the quality and durability of ‘Obilnaja’ and ‘Black Star’ plum varieties

Abstract The research work aimed at investigating the effect of pre-harvest gibberellic acid (GA3) treatment on the quality of ‘Obilnaja’ and ‘Black Star’ Japanese plum varieties. GA3 was sprayed onto the trees during the fruit color break at 0, 25, 50, 75, and 100 ppm concentrations. After pre-cooling, the plums were placed in modified atmosphere packages and exposed to the following conditions as follows: short storage-transportation (ST) [20 days at 2 °C and 90% relative humidity (RH)]; distribution center (DC) (5 days at 6 °C and 80% RH), and shelf life conditions (SL) (2 days at 20 °C and 70% RH). Pre-harvest GA3 treatments increased the fruit weight and size. Treatment of GA3 at 50, 75, and 100 ppm increased the fruit flesh firmness and total soluble substances (TSS) values in both the plum varieties during storage, transport, and marketing; it also limited the weight loss during the marketing process. Treatment of GA3 had no significant effects on the color, titratable acidity (TA), and the total phenolic and antioxidant activity values of plums. Pre-harvest GA3 treatment at 50 ppm GA3 can be thus recommended for both the plum varieties due to its effect on the fruit quality.

Phytochemical investigations on ‘black glumed’ Njavara (Oryza sativa L.), the medicinal rice, as compared to staple varieties and evaluation of their antioxidant, anti-inflammatory and anticancer effects

The study was planned to investigate the bioactive compounds in Njavara compared to staple varieties and their bioactivity to substantiate the medicinal properties. Results of the study on chemical indices, antioxidant activity and antiinflammatory activity (in vivo) of Njavara black rice bran and rice in comparison with non-medicinal varieties like Sujatha and Palakkadan Matta rice bran and rice are given. The phytochemical investigation and quantification of Njavara extracts in comparison with staple varieties are detailed in this study. The last chapter is divided in three sections (A, B and C). Section A comprises the antioxidant activity by in vitro assays like DPPH, superoxide anion radical and hydrogen peroxide scavenging activity of the compounds. Also, theoretical studies using DFT were carried out based on DPPH radical scavenging activity for understanding the radical stability and mechanism of antioxidant activity. Section B comprises the anti-inflammatory activity of the identified compounds namely tricin and two flavonolignans in both in vivo and in vitro models. Section C describes the cytotoxicity of the rare flavonolignans, tricin 4’-O-(erythro-β-guaiacylglyceryl) ether and tricin 4’-O-(threo-β-guaiacylglyceryl) ether towards multiple cancer cells belonging to colon, ovarian and breast tumours.

Successful rescue and field establishment of native banana varieties severely affected by rhizome rot

Rhizome rot disease caused by Erwinia spp. is emerging as a major problem in banana nurseries and young plantations worldwide. Management of the disease is possible only in the initial stages of development. Currently no method is available for rescuing plant material already infected with this pathogen. A total of 95 Nanjanagud Rasabale and 212 Elakki Bale suckers were collected from different growing regions of Karnataka, India. During nursery maintenance of these lines, severe Erwinia infection was noticed. We present a method to rescue infected plants and establish them under field conditions. Differences were noticed in infection severity amongst the varieties and their accessions. Field data revealed good establishment and growth of most rescued plants under field conditions. The discussed rescue protocol coupled with good field management practices resulted in 89.19 and 82.59 percent field establishment of previously infected var. Nanjanagud Rasabale and var. Elakki Bale plants, respectively.

Effects of phosphorus and water stress on shoot and root growth and on mycorrhization of different pearl millet (Pennisetum glaucum (L.) R. Br.) varieties from West Africa

This research work aimed at investigating the physiological mechanisms of tolerance of pearl millet to low soil Phosphorus availability and drought under the Sahelian conditions.

Effects of row spacing on productivity and nodulation of two soybean varieties under hot sub-moist tropical conditions in south-western Ethiopia

The objective of this study was to determine the optimum row spacing to improve the productivity of two soybean (Glycine max L.) varieties under the tropical hot sub-moist agroecological conditions of Ethiopia. A two-year split-plot design experiment was conducted to determine the effect of variety (Awasa-95 [early-maturing], Afgat [medium-maturing]) and row spacing (RS: 20, 25, 30, 35, 40, 45, 50, 55, 60 cm) on the productivity, nodulation and weed infestation of soybean. Seed and total dry matter (TDM) yield per ha and per plant, and weed dry biomass per m^2 were significantly affected by RS. Soybean variety had a significant effect on plant density at harvest and some yield components (plant height, number of seeds/pod, and 1000 seed weight). Generally, seed and TDM yield per ha and per plant were high at 40 cm RS, and weed dry biomass per m^2 was higher for RS >= 40 cm than for narrower RS. However, the results did not demonstrate a consistent pattern along the RS gradient. The medium-maturing variety Afgat experienced higher mortality and ended up with lower final plant density at harvest, but higher plant height, number of seeds per pod and 1000 seed weight than the early-maturing variety Awasa-95. The results indicate that 40 cm RS with 5 cm plant spacing within a row can be used for high productivity and low weed infestation of both soybean varieties in the hot sub-moist tropical environment of south-western Ethiopia.

Perceptions of the impacts of genetically modified cotton varieties: a case study of the cotton industry in Gujarat, India

The paper reports the findings of a study designed to consider the impact of the adoption of Bt cotton on markets, businesses, and institutional arrangements in India. Given that evidence to date suggests that widespread adoption of Bt cotton by farmers is likely to increase production, this study aims to assess possible implications for markets (access to inputs, prices of inputs and outputs, etc.) and local industries and to identify potential winners and losers. The results suggest that there are impacts on the cotton industry following from the release of Bt hybrids, and so far the impacts are most noticeable "upstream" (i.e., the input suppliers), where companies are rapidly moving away from the sale of bollworm insecticide and attempting to sell Bt seeds. Seed companies are looking for partnerships with Monsanto, the owner of the Bt gene. One reason that companies are keen to move away from insecticide is so they can avoid the need for credit supply to their customers. Seed purchase is not normally through credit, whereas insecticide purchase is. Issues for companies "downstream" (gins, textile manufacturers) relate more to the better quality of Bt cotton and the need for adequate segregation of Bt and non-Bt cotton.

Factors affecting the adoption of leguminous cover crops in Nigeria and a comparison with the adoption of new crop varieties

This paper presents the results of (a) On-farm trials (eight) over a two-year period designed to test the effectiveness of leguminous cover crops in terms of increasing maize yields in Igalaland, Nigeria. (b) A survey designed to monitor the extent of, and reasons behind, adoption of the leguminous cover crop technology in subsequent years by farmers involved, to varying degrees, in the trial programme. particular emphasis was placed on comparing adoption of leguminous cover crops with that of new crop varieties released by a non-governmental organization in the same area since the mid 1980s. While the leguminous cover crop technology boosted maize grain yields by 127 to 136% above an untreated control yield of between 141 and 171 kg ha(-1), the adoption rate (number of farmers adopting) was only 18%. By way of contrast, new crop varieties had a highly variable benefit in terms of yield advantage over local varieties, with the best average increase of around 20%. Adoption rates for new crop varieties, assessed as both the number of farmers growing the varieties and the number of plots planted to the varieties, were 40% on average. The paper discusses some key factors influencing adoption of the leguminous cover crop technology, including seed availability. Implications of these results for a local non-governmental organization, the Diocesan Development Services, concerned with promoting the leguminous cover crop technology are also discussed.

The genotypic variation of the antioxidant potential of different tomato varieties

There is increasing interest in the ability of diets rich in polyphenols to modulate age-related diseases and promote healthy ageing. We have conducted a pilot experiment with eight tomato varieties to correlate the total antioxidant capacity of the tomato variants with the specific constituent flavonoids present. A strong correlation was observed with the flavonol rhamnoglucoside rutin but not with other flavonoids, such as naringenin chalcone, or hydroxycinnamates, such as chlorogenic, which are also present in the tomato. To test the rigor of this correlation a second study was undertaken with a further 37 tomato varieties selected for low, medium and high rutin levels. We show that the flavonol rutin contributes to the greatest extent to the antioxidant capacity of tomatoes and suggest that this flavonoid may be a useful target for up-regulation in tomatoes in order to improve their antioxidant status.

Comparison of the antioxidant activity of two Spanish onion varieties

Phenol content and antioxidant activity of two Spanish onion varieties, namely white onion and Calcot de Valls, have been studied. White onions contained higher phenol content than Calcot onions, with values which ranged from 2.57 +/- 0.51 to 6.53 +/- 0.16 mg gallic acid equivalents/g dry weight (GAE/g DW) and 0.51 +/- 0.22 to 2.58 +/- 0.16 mg GAE/g DW, respectively, depending on the solvent used. Higher phenol content was associated with higher antioxidant capacity. White onion extracts had the highest antioxidant activity at 86.6 +/- 2.97 and 29.9 +/- 2.49 mu mol Trolox/g DW for TEAC and FRAP assays, respectively, while the values for the Calcot variety were 17.5 +/- 0.46 and 16.1 +/- 0.10 mu mol Trolox/g DW. The antioxidant capacity of freeze dried powder from both onion varieties was also tested in sunflower oil-in-water emulsions, and hydroperoxide formation was monitored during storage at 40 degrees C. In accordance with differences in phenol content, Spanish white onions had better antioxidant activity.. while Calcot was only effective in the early stages of the oxidation process. (c) 2007 Elsevier Ltd. All rights reserved.