Band 11, Heft 3 -

Coagulants and raw materials effects on the sensory characteristics of acid and salt-induced soft tofu-type gels were investigated and compared. Gels made from soybean were more whitish than the ones made from SPI with L* values between 79.743 and 80.847. Similarly, the raw materials affected more the volatile compounds composition than the coagulants. It was also established that CaSO 4 produced softer gels with hardness values varying between 104 and 145 g compare to 173 and 302 g for acid-induced gels. Salt-induced soybean gels demonstrated the highest score for beany taste (7.67), bitter taste (7.39) and mouthfeel (7.25). Correlation results depicted that the volatile compounds did not have a positive nor negative significant impact on mouthfeel of soft tofu gels; however, they were significantly correlated to beany and bitter taste. Furthermore, all free amino acids were positively correlated to beany, bitter taste and mouthfeel except cysteine. Glutamic acid, alanine, tyrosine, methionine and isoleucine free amino acids showed a significant influence on beany taste; while, glutamic acid, tyrosine, methionine and isoleucine showed a significant impact on bitter taste.

Chitosan microspheres (CsMs) that encapsulate salidroside (Sal) were prepared by the emulsion crosslinking method with naturally occurring genipin (Gp) and then examined for their in vitro release. Sal-loaded CsMs (Sal-CsMs) showed nearly spherical and smooth surfaces with internal voids. The particle size of Sal-CsMs ranged within 0.56–5.01 μm, and their encapsulation efficiency and loading capacity were beyond 77.58% and 23.29%, respectively. The stability of Sal improved after entrapment into the CsMs. The release rate of Sal from CsMs was initially rapid, followed by sustained release. The release behavior depended on the pH of the release medium. The main release mechanisms underlying the release procedure were anomalous behavior and Fickian diffusion. These results indicated that CsMs with a novel crosslinker of Gp was a potential carrier system for producing functional foods containing Sal.

This article uses several liquid diffusion models to describe convective drying of bananas cut into cylindrical pieces. A two-dimensional numerical solution of the diffusion equation with boundary condition of the third kind, obtained through the finite volume method, was used to describe the process. The cylindrical pieces were cut into the following dimensions: length of about 21 mm and average radius of 15 mm. Drying air temperatures were 40°C, 50°C, 60°C and 70°C. In order to determine the process parameters, an optimizer was coupled with the numerical solution. A model that considers the shrinkage and variable effective moisture diffusivity well describes drying for all the experimental conditions, and enables to predict the moisture distributions at any given time. For this model, the determination coefficient has varied from 0.99937 (70°C) to 0.99995 (40°C), while the chi-square ranged from 3.41 × 10 −4 (40°C) to 4.15 × 10 −3 (70°C) .

Kofter is a traditional product which is composed of water, molasses and starch. The quality of Kofter depends on many factors involving concentration of the ingredients, starch concentration and type, composition and type of the molasses and drying temperature and time. In the present study, the effect of molasses concentration (75–25%) on the pasting and textural properties of the Kofter samples was investigated. All pasting properties (peak viscosity, trough viscosity, breakdown viscosity, final viscosity, setback viscosity, peak time, pasting temperature) were significantly affected by molasses concentration used in the formula. The increase in water concentration generally caused increase in hardness, adhesiveness, gumminess and chewiness value of the Kofter samples. Sensory analysis was also performed to determine mostly preferred sample regarding appearance, color, texture, taste, odor and overall preference. According to the sensory results, Kofter sample including 40% molasses and 60% water was found to be mostly preferred sample.

Microwave-assisted extraction (MAE) was investigated for recovering of total phenolic compounds from dried waste grape skins using a domestic microwave oven. Influence of vessel geometry, irradiation cycles, irradiation power and time was investigated. The results in terms of phenolics yield, antioxidant capacity and energy consumption were compared with a reference solid–liquid extraction (SLE) carried out for 2 h at 60°C. Equivalent yield of total phenolics as in SLE was achieved with a MAE extraction time of 1,033 sec (corresponding to 83 sec of irradiation at 900 W, 83% saving in extraction time compared to SLE and with a 70% energetic efficiency). Pre-maceration of samples and solvent pre-heating are proposed for large-scale industrial processes to enhance phenolics extraction and process efficiency.

This study aimed to determine the mineral composition and anti-nutritional factors, oxalate and phytate, of yam and taro grown in southern Ethiopia. In addition, the effect of cooking at different temperatures on the mineral compositions and anti-nutritional factors together with respective molar ratios Ca:oxalate, Zn:phytate, Ca:phytate and (Ca × phytate):Zn was determined. The mineral compositions were found to be: 21.8–15.7, Ca; 11.4–12.1, Na; 7.02–7.24, Mg; 6.47–14.14, Zn; 2.04–4.3, Fe; 0.26–0.88, Mn; 0.50–0.60, Cu; 0.57–0.82, Co; and 0.20–2.15, Ni in mg/100 g in the raw yam samples and 41–53, Ca; 6.21–7.21, Na; 7.32–7.58, Mg; 42–50, Zn; 1.93–3.25, Fe; 1.71–5.88, Mn; 0.46–0.51, Cu; 0.65–0.95, Co; and 0.18–0.68 Ni in mg/100 g of raw taro samples. Mineral content decreased by cooking except Fe and Ca in one variety of taro where they show a bit increment. The anti-nutritional factor to mineral ratio tends to imply that the relative bioavailability of the minerals after cooking was found to be increased except for that of Fe. These tubers may present health hazard potential, which in turn demands proper processing before consumption to eliminate the toxic effects of anti-nutritional factors.

Linoleic acid was isolated effectively from Sambucus williamsii (SW) seed oil which was extracted by high-pressure fluid and its biological activities were investigated. Linoleic acid was isolated from the oil by urea inclusion, the yield was 65.81% and the purity was 92.12%. 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay was used to determine the antioxidant activity of linoleic acid. IC 50 of DPPH radical scavenging activity of linoleic acid was 61.92 mg/mL. The antiglycemic activity of linoleic acid was evaluated by determining its inhibitory effect on α-glucosidase. The results showed that α-glucosidase was inhibited to a certain extent by linoleic acid (1.56–25 mg/mL). In addition, the hypolipidemic activity of linoleic acid was investigated in vivo using hyperlipidemia mice models fed with the linoleic acid at doses of 1, 2, 4 g/kg BW (body weight). The results showed that serum lipid levels were highly significantly ( p <0.01) improved, which indicated the hypolipidemic activity of linoleic acid. The linoleic acid extracted from SW seed oil was proved to possess good antioxidant, antiglycemic and hypolipidemic activity in human diets, which may have industrial use.

The study examined the impact and interactions of cashew apple juice (CAJ) concentration, pH, NaNO 3 concentration, inoculum size and time on gluconic acid (GA) production in a central composite design (CCD). The fermentation process and parameters involved were modeled and optimized using artificial neural network (ANN) and response surface methodology (RSM). The ANN model established the optimum levels as CAJ of 250 g/l, pH of 4.21, NaNO 3 of 1.51 g/l, inoculum size of 2.87% volume and time of 24.41 h with an actual GA of 249.99 g/l. The optimum levels predicted by RSM model for the five independent variables were CAJ of 249 g/l, pH of 4.6, NaNO 3 of 2.29 g/l, inoculum size of 3.95% volume, and time of 38.9 h with an actual GA of 246.34 g/l. The ANN model was superior to the RSM model in predicting GA production. The study demonstrated that CAJ could serve as the sole carbon source for GA production.

A mathematical model for the rotary dryer that determines the total residence time is developed. Experiments were performed in a laboratory-scale direct contact rotary dryer with the gas flowing concurrently with the solids. The model predictions depicted that the total residence time decreases with increasing the inclination of the rotary drum, the speed of rotation and the radius of rotary drum. The validation of the model was carried out experimentally for maize while varying the inclination of the rotary drum and the speed of rotation. The experimental results were observed to be in good agreement with the model predictions.

The aim of this study was to optimize the spray drying process parameters for sweet corn enzymolysis liquid concentrate (SCELC). Experimental design with inlet temperature (170–190°C), SCELC/maltodextrin (MD) ratio (0.25–4) and inlet feed rate (800–1000 mL h −1 ) as independent variables was studied to investigate the effects on product responses. The corresponding results showed that an increase in the inlet temperature resulted in sweet corn powder with lower moisture, bulk density, L * value, H ° value and higher water solubility index. Meanwhile, an increase in MD ratio brought lower moisture and higher L * value, H ° value, water solubility index. It was also found that an increase in the inlet feed rate caused higher moisture and lower water solubility index. The highest production yield was achieved at 42.86% with optimized inlet temperature of 177.66°C, SCELC/MD ratio of 0.84 and inlet feed rate of 834.50 mL h −1 . Accordingly, the production yield, moisture content, bulk density, water solubility index, L * and H ° value were 42.86%, 3.57%, 0.45 g/cm 3 , 96.54 g/100 g, 84.46, and 83.54, respectively.

Convective hot air drying was used to dry date fruits at different air temperatures and velocities. The kinetics of drying was evaluated by 10 common models. The fruit color and texture were examined before and after drying. Drying time increased as both drying temperature and air velocity decreased. Best fits to the experimental data were provided by the Midilli and Kucuk model, followed by the logarithmic, two-term exponential, and Henderson–Pabis models. Drying affected the fruit color and texture. To minimize such changes, the range of drying temperature and air velocity should be 60–70°C and 2 m/s, respectively.

This study is designed to investigate drying kinetics, nutrient retention and rehydration ratio of onion slices under air-impingement jet drying (AIJD) with different drying temperatures (40, 50 and 60°C), air velocities (11, 12 and 13 m/s), and the distance between jet nozzles and material box (0, 40 and 80 mm). Additionally, the influence of AIJD and hot air drying (HAD) on drying efficiency and product quality of onion slices was comparatively investigated. It was found that the moisture effective diffusivity of onion slices under AIJD ranged from 3.51 × 10 −10 to 5.51 × 10 −10 m 2 /s, and the activation energy ( E a ) of onion determined from Arrhenius equation was 14.73 kJ/mol, and ascorbic acid content (AAC), total phenolic content (TPC) and DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging activity (DSA) significantly decreased in the dried onions compared to that in fresh onion. In addition, the results suggest that the Modified Page model provides the best fit for AIJD curves. Furthermore, AIJD product is better than HAD both in decreasing drying time and enhancing drying rate, AAC, TPC, DSA and rehydration ratio. Accordingly, the AIJD method has advantages in drying time and quality of products, indicating that this technology can be widely applied to food drying process.