Volume 4, Issue 1

The starch yields from both whole (MSI1) and decorticated mung bean seeds (MSI2) were 26.00 and 30.50% on total seed basis and 64.40 and 75.55% of total starch. Chemical analysis of the starch isolates i.e. MSI1 and MSI2 showed that they contained 9.00 and 8.90% moisture, 0.76 and 0.80% protein, 0.05 and 0.09% oil and 0.20 and 0.13% ash , respectively. The results also indicated that the purity of starch isolates was high. Microscopic examination (400X) showed that most mung bean starch granules had irregular shapes, which varied from oval, round to bean-shaped. Mung bean starch granule size varied from 7.65-33.15 µm with mean value at 20.40 µm. Studying the physico-chemical properties of mung bean starch indicated that the gelatinization temperature range was 65-69-75°C at initial, midpoint and final gelatinization of starch granules. Mung bean starch had a considerably lower degree of syneresis than other legume starches. Moreover, gel consistency decreased as starch concentration was increased. Viscosity of mung bean starch was high indicating that it had higher resistance to swelling and rupture than did cereal starches. The results indicated that the swelling power and solubility of the starch increased with increasing temperature. In addition, the solubility percentage increased, but non-linearly, with increasing swelling power.

An evaporative cool chamber was constructed with the help of baked bricks and riverbed sand. Maximum and Minimum temperature and relative humidity were recorded inside and outside the chamber for about one month. It was found that inside temperature was about 10-15°C lower than outside temperature and inside humidity was about 30-40 % higher than outside. A comparative study was made for the storage of different fruits and vegetables inside the cool chamber and in the ambient condition and their weight loss and freshness were observed everyday. It has been recorded that weight loss of fruits and vegetables kept inside the chamber was lower than those stored outside the chamber. The fruits and vegetables were fresh up to 3 to 5 days more inside the chamber than outside. The evaporative cool chamber does not require mechanical or electrical energy input and can be constructed with locally available material with unskilled labour. It is economical and can store the fruits and vegetables for 3 to 5 days with no significant loss.

Tofu – Soycurd, is one of the important non-fermented soybean products, which has been widely used in a variety of dishes by oriental people for many centuries. Normally in the preparation of Tofu, synthetic coagulants such as calcium sulphate, magnesium chloride, Glucono-?-lactone, etc., are used. These coagulants are not readily available sometimes for use in the household and not available easily in the rural areas. Hence, an attempt was made to use natural coagulants of plant origin (Citrus lemon, Garcinia indica, Tamarindus indica, Averrhoa carambola, Averrhoa bilumbi, Phyllanthus distichus, Tamarindus indica flower extract, Hibiscus canabinus and Passiflora edulis) in preparation of Tofu. Yield, texture, proximate composition and sensory quality of Tofu prepared using natural coagulants were analyzed and a comparative evaluation was made between Tofu obtained from synthetic coagulants. Results showed that use of natural coagulants in preparation of Tofu increased the yield (24.5g/100 ml of soymilk). Total crude protein estimation revealed that the protein content in Tofu prepared using natural coagulants was comparatively higher than the synthetic coagulants (61.4% on dry weight basis). Texture analysis results of Tofu prepared using different coagulants showed that Garcinia indica extract produced Tofu with hard texture, more cohesiveness and chewiness compare to other coagulants followed by Calcium sulfate and Tamrindus indica. Sensory analysis of Tofu showed Citrus lemon extract produced best Tofu with higher overall quality in terms of appearance, texture, taste, flavor and color followed by Tamarindus indica.

Natural fruit fibres have been used when spray drying a bioactive material, hibiscus extract, which contains significant amounts of anthocyanin. The extracts, when spray dried alone, produce powders that adsorb so much moisture that they deliquesce, forming liquid droplets in storage. The use of these fibres has demonstrated that the resulting extract and fibre powders do not deliquesce and reach a stable moisture state as powders. This situation of greater stability in the extract and fibre powders, regarding moisture sorption, than the spray dried extracts alone, may be due to the crystallization in the final extract and fibre powders caused by the fibres. Using this crystallization process to stabilize a bioactive extract in this way appears to be a novel process.

A mathematical model was developed to predict the change of temperature distribution with time in the radial and axial directions in a simulated sealed cylindrical pit. The finite difference method was used in the model to calculate the conductive heat transfer. The model predicts the grain temperatures in the pit during the storage period using input data of initial grain temperature, storage time and number of spatial elements in both radial and axial directions. Other input data include the finite difference spatial increment in both directions, the finite time increment, temperatures of soil surrounding the pit and the physical properties of grain, pit wall material and surrounding soil. To validate the model, predicted temperatures were compared with measured data for wheat of Apollo variety being stored in a simulated sealed pit for a period of 70 days. The wheat was stored in a cylindrical mild steel tank with 0.6 m in both diameter and height. The initial uniform grain temperature was 15°C and the initial uniform grain moisture content was 12.45% (w.b.). Both measured and predicted wheat temperatures attained steady state within a short period of storage (2 to 6 days) and this equilibrium was maintained throughout the experiment period. At the end of the storage period, the grain temperatures were decreased by an average of 2.63°C and the grain moisture contents were increased by an average of 1.62% (w.b.) at the top layer of the pit. For the bottom layer of the pit, the grain temperatures increased by an average of 7.04°C and the grain moisture contents were decreased by an average of 0.50% (w.b.) The conductive heat transfer model predicted the grain temperatures with a standard error of estimate between measured and predicted of 0.12°C -0.25°C.

This study involved the determination of convective heat transfer coefficient in both helical and straight tubular heat exchangers under turbulent flow conditions. The experiments were conducted in helical heat exchangers, with coils of two different curvature ratios (d/D = 0.114 and 0.078), and in straight tubular heat exchangers at various flow rates (1.89 x 10-4 - 6.31 x 10-4 m3/s) and for different end-point temperatures (92 - 149 °C). The results show that the overall heat transfer coefficient (U) in the helical heat exchanger is much higher than that in straight tubular heat exchangers. In addition, U was found to be larger in the coil of larger curvature ratio (d/D = 0.114) than in the coil of smaller curvature ratio (d/D = 0.078). The inside (hi) and outside (ho) convective heat transfer coefficients were determined based on the overall heat transfer coefficient and a correlation to compute the inside convective heat transfer coefficient (hi) as a function of NRe, NPr, and d/D was developed.

Experimental methods of ohmic heating of parboiling of paddy have been presented. The temperature of the parboiling varied from 110 to 150 °C. Milling performance, cooking qualities and protein content of parboiled rice have been tested and it was found that these requirements are optimum at 130 °C. Milling performance of the parboiled rice by ohmic heating is better than the conventional parboiled rice. The cooking qualities of the parboiled rice are quite comparable with conventional parboiled rice.

Some varieties of sorghum (Sorgum bicolor) available in the North of Cameroon have been characterized for to their ability to meet consumers and industries requirements. Local varieties of sorghum, namely ``Zouaye," ``Djigari," ``Damougari" have been compared to four selected varieties with good agronomic characteristics (S35, CS-210, CS-95, CS-54). Results indicate that the varieties CS-95, CS-54, and ``Madjeru" present very high percentages of cut brown grains with a variation from 48% to 87%. The variety ``Dmougari" seems harder than the others with a PSI of 19±2.6. Varieties CS-210 and CS-95 appear to be most tender with successive PSI of 11.8±5.21 and 12.2±1.2. All local varieties (Madjeru, Zouaye, Damougari, Djigari) have shown a 1000-kernel weight ranging between 21.9±2.6g and 25.5±1.5g, whereas selected varieties (S35, CS-210, CS-95, CS-54) present 1000-kernel weight binds between 15.43 ±2.5g and 19.31±5.21 g. The majority of the studied grains present an index of vitrosity between 1.6 and 4.85, except CS-210, Madjeru, Djigari which are semi-vitreous (with indices of vitrosity ranging between 3 and 4. Dihurin content of all varieties ranges from 108±15 to 225±23 (ppm). The colour of the grain shows that the improved varieties present yellow blades and yellow ivory colours, whereas the local varieties are brown and red.

The present research is aimed at a formulation of the entomopathogenic fungi, Beauveria bassiana (Bal.) Vuillemin and Metarhizium anisopliae (Metch.) Sorokin, in two types of diatomaceous earth dusts, fossil shield and Silico-Sec, are then applied against the adults of three species of stored-grain insects: Sitophilus oryzae L., Rhyzopertha dominica Fab. and Tribolium castaneum Herbs. Effect of the treatment was assessed by comparing the mortality percentage of the adults of the three insect species exposed to the formulated fungi with that of the adults exposed to the unformulated fungi or the diatomaceous earth dusts or the undisturbed control. Results obtained from these exposures have indicated that treatment of the adults with the formulated fungi resulted in a significantly higher mean mortality percentage compared to the treatment with the unformulated fungi or the diatomaceous earth dusts or the undisturbed control. A synergistic interaction between the effect of fungal species and the diatomaceous earth dusts was shown. Viability of conidia of both fungal species in diatomaceous earth dusts was assessed by calculating the germination percentage of the conidia over time. Results indicated a small loss of mean germination percentage for formulated conidia of both fungal species versus a high loss of mean germination percentage for the unformulated conidia, thus the diatomaceous earth dusts used in the formulation of both fungi demonstrated a negligible effect on the viability of formulated conidia compared to the unformulated.

The instantaneous controlled pressure drop process (or D.I.C process: ``Détente Instantanée Contrôlée") was used as a pre-treatment prior to pectin acid extraction from orange peel. This process involves subjecting the orange peel for a short time to steam pressure varying from 100 to 700 kPa, followed by an instantaneous decompression to vacuum at 5 kPa. Effects of processing pressure, moisture content of peels before the thermomechanical treatment and processing time were examined with response surface methodology. The optimal conditions were determined and the response surfaces were plotted from the mathematical models. The Fisher test and p-value indicated that both processing pressure and moisture content of peels before the pre-treatment had a highly significant effect on the pectin yield. The quadratic effect of processing pressure as well as the interaction effects of the initial moisture content and processing time also had a significant effect on the response. Moreover, the kinetics of pectin extraction showed that after few minutes of hydrolysis, the yields of pectin were systematically higher than that of the control sample and this is important from industrial point of view because the hydrolysis of pectin is generally performed in 10-15 minutes.

Flow behavior of chocolate drinks from Cupuassu (Theobroma grandiflorum, Sterculiaceae) from instantised and normal formulation, and enriched with calcium, were studied. Flow behavior was described using common rheological models (Newton, Power Law, and Bingham plastic). Experimental results, obtained at 25 oC and 40oC, fitted mostly the Ostwald and Bingham models, with R2 ? 0.997. The Newtonian model has 0.886 ? R2 ? 0.991. At 25 oC, as expected, viscosity of samples was higher and pseudoplasticity increased (n values were lower than 1). The spray-dryer process lead to differences of rheology of the ``chocolate'' milk drinks. The addition of microcrystalline cellulose plus calcium leads to a lower viscosity.

A food grade divinylbenzene adsorbent resin was used to separate/recover plyphenolics from diluted apple juice concentrate. The work was carried out to investigate the effect of processing parameters on the adsorption process, to compare the efficiency of divinylbenzene adsorbent resin to that of ethylene glycol cross-linked polymethylmethacrylate adsorbent resin used in our previous study and to determine the effect of oxygen on the adsorption of polyphenolics process.A laboratory scale adsorption was determined by mixing weighed amounts of the polymer with a diluted apple juice concentrate at 10–60 oC and at pH values ranging from 2.0 to 3.9. At regular intervals, samples were withdrawn from the aqueous phase. Total phenolics, absorbance values at 280 and 420 nm, and the amounts of individual phenolics remaining in the liquid phase were determined. The analytical data were fitted to the Langmuir and Freundlich isotherms.Findings from this study are in agreement with Kammerer et al. (2006) but, in contrast to previous studies, the pH value significantly affected the adsorption onto the resin. HPLC analyses revealed different affinities of individual compounds, which enabled selective enrichment of certain phenolics in the liquid phase or on the sorbent surface. HPLC profiling showed that the polyphenolics recovered did not differ significantly from those in the original apple extracts. This has confirmed that there is minimal damage during processing. The major losses in the process were due to polyphenols not binding to, or not being recovered from, the adsorbent. Optimization of the process would enable the losses to be minimized and up to 80% of the polyphenolics could be recovered in the extracts.Desorption studies were performed using a resin with known amounts of adsorbed phenolic compounds. Elution was carried out by an automated pressurized liquid extraction system, studying the effects of temperature (40–180 oC) and solvents (water, ethanol, methanol). Again, individual compounds behaved differently, depending on their hydrophobicity. Therefore, a systematic change of parameters for the adsorption and desorption process can be helpful for the recovery of purified plant extracts enriched in certain target compounds.

The effects of sucrose concentration, pH, temperature and aeration rate on the production of biomass and inulinase (2,1-beta-D-fructan fructanohydrolase, EC 3.2.1.7) were investigated using fed-batch fermentation by Kluyveromyces marxianus var. bulgaricus. The best sucrose concentration for enzyme activity was 10 g L-1, whereas activity was inhibited when the sucrose concentration was 20 g L-1. Enzyme activity was strongly influenced by pH of the culture. pH 5.0 was the most suitable for both enzyme activity and cell growth, achieving 98.04 U mL-1 and 14.05 g L-1, respectively, after 72 hours of cultivation. The highest production of inulinase and biomass was observed at temperatures of 25oC and 30oC, whereas a decrease in activity was observed at 35oC and 40oC. The best aeration rate was 1.0 vvm. The increase in aeration rate or oxygen injection provided no increase in enzyme activity and biomass.