Ohmic heating as a pre-treatment in solvent extraction of rice bran.

Rice bran, which is one of the major by products of paddy contain high quality proteins and edible oil apart from fibre, ash and NFE (nitrogen free extract). The existing solvent extraction method employs n-hexane as the most viable solvent for the extraction of oil from rice bran. But the high cost and scarce availability of n-hexane resulted in uneconomical extraction of rice bran oil. In this study, rice bran was ohmically heated for different time periods(1, 2 and 3 min) with different current values (5, 15 and 20 A) and with different concentration of sodium chloride (1 M, 0.1 M and 0.01 M) as conducting medium. The ohmically heated rice bran was subjected to extraction studies. Ohmic heating of rice bran of paddy varieties Red Triveni and Basmati reduced the extraction time by nearly 75 % and 70 % respectively and gave a maximum quantity of oil extracted when compared to bran, which was not ohmically heated. From the experiments with varying concentrations, residence time of ohmic heating and currents, it was found that ohmically heating the rice bran with 1 M sodium chloride solution and with a current value of 20 A for 3 min gave maximum oil extraction with minimum extraction time.

Physico-chemical changes in tomato with modified atmosphere storage and UV treatment.

Physico-chemical changes in ripe tomato (Lycopersicon esculentum Mill.) were analyzed on day 0 and 2 weeks after ultraviolet-C (UV-C) light treatment or modified atmosphere (MA) storage and combined UV-C + MA storage at 10 °C. Modified atmosphere packaging (MAP) film was used to create MA conditions. The tomatoes were evaluated for surface colour, mass loss, firmness, respiration rate, total soluble solids and antioxidant capacity. The tomatoes treated with UV-C and MA storage underwent least changes in their physico-chemical properties, indicating that combination of UV-C and MA storage was successful in retaining the attributes of the fresh product. The increase in antioxidant capacity of the tomatoes during UV-C treatment suggested that UV treatment during post harvest handling may be successfully combined with MA storage, resulting in a product with better nutritive value.

Predicting the Moisture Ratio of a Hami Melon Drying Process Using Image Processing Technology.

For food drying, moisture content and shrinkage are vital in the drying process. This paper is concerned with the moisture ratio modeling and prediction issues of the Hami melon drying process. First, an experimental system was developed; it included an adjustable-power microwave drying unit and an image-processing unit. The moisture contents and the areas of Hami melon slices at different times were sampled in real time. Then, the expression of the moisture ratio with regard to shrinkage was derived by using the Weierstrass approximation theorem. A maximum likelihood fitness function-based population evolution (MLFF-PE) algorithm was then put forward to fit the moisture ratio model and predict the moisture ratio. The results showed that the proposed MLFF-PE algorithm was effective at fitting and predicting the moisture ratio model of the drying process of Hami melon slices.

Estimating the Moisture Ratio Model of Cantaloupe Slices by Maximum Likelihood Principle-Based Algorithms.

As an agricultural plant, the cantaloupe contains rich nutrition and high moisture content. In this paper, the estimation problem of the moisture ratio model during a cantaloupe microwave drying process was considered. First of all, an image processing-based cantaloupe drying system was designed and the expression of the moisture ratio with regard to the shrinkage was built. Secondly, a maximum likelihood principle-based iterative evolution (MLP-IE) algorithm was put forward to estimate the moisture ratio model. After that, aiming at enhancing the model fitting ability of the MLP-IE algorithm, a maximum likelihood principle-based improved iterative evolution (MLP-I-IE) algorithm was proposed by designing the improved mutation strategy, the improved scaling factor, and the improved crossover rate. Finally, the MLP-IE algorithm and MLP-I-IE algorithm were applied for estimating the moisture ratio model of cantaloupe slices. The results showed that both the MLP-IE algorithm and MLP-I-IE algorithm were effective and that the MLP-I-IE algorithm performed better than the MLP-IE algorithm in model estimation and validation.

Online Machine Vision-Based Modeling during Cantaloupe Microwave Drying Utilizing Extreme Learning Machine and Artificial Neural Network.

Online microwave drying process monitoring has been challenging due to the incompatibility of metal components with microwaves. This paper developed a microwave drying system based on online machine vision, which realized real-time extraction and measurement of images, weight, and temperature. An image-processing algorithm was developed to capture material shrinkage characteristics in real time. Constant-temperature microwave drying experiments were conducted, and the artificial neural network (ANN) and extreme learning machine (ELM) were utilized to model and predict the moisture content of materials during the drying process based on the degree of material shrinkage. The results demonstrated that the system and algorithm operated effectively, and ELM provided superior predictive performance and learning efficiency compared to ANN.

Microwave-assisted extraction of phenolic antioxidants from potato peels.

A response surface method was used to optimize the microwave-assisted extraction parameters such as extraction time (t) (min), solvent (methanol) concentration (S) (v/v) and microwave power level (MP) for extraction of antioxidants from potato peels. Max. total phenolics content of 3.94 mg g⁻¹ dry weight (dw) was obtained at S of 67.33%, t of 15 min and a MP of 14.67%. For ascorbic acid (1.44 mg g⁻¹ dw), caffeic acid (1.33 mg g⁻¹ dw), ferulic acid (0.50 mg g⁻¹ dw) max contents were obtained at S of 100%, t of 15 min, and MP of 10%, while the max chlorogenic acid content (1.35 mg g⁻¹ dw) was obtained at S of 100%, t of 5 min, and MP of 10%. The radical scavenging activity of the extract was evaluated by using the DPPH assay and optimum antioxidant activity was obtained at S of 100%, t of 5 min, and MP of 10%.

Optimization of the proportions of four wastewaters in a blend for the cultivation of microalgae using a mixture design.

A 2nd degree mixture design was used to determine the optimal blend prepared from four wastewater streams to produce microalgae-based biomass. The streams consisted of a liquid digestate from an anaerobic digestion process, a landfill leachate, a septic-system sludge treatment plant liquid, and a wastewater treatment plant effluent. The mixture regression analysis indicated that blends with higher proportions of treated effluent and digestate improved cells growth, while the use of leachate was detrimental to the growth. The global solution of the mixture optimization predicted a maximum value of biomass productivity of 22.76 mg L-1 d-1, in a blend consisting of 19% treated effluent, 21% digestate, and 60% water. Proportions of leachate higher than 13.33% were detrimental to the growth. The concentration of ammonia-N in the blends ranged from 0.39 to 150 mg L-1 d-1, and its toxicity effect on the cells diminished with increasing amounts of organic carbon in the cultivation medium.

High-humidity hot air impingement blanching alters texture, cell-wall polysaccharides, water status and distribution of seedless grape.

Blanching pretreatment plays an essential role in fruits and vegetables processing to obtain excellent final products. The purpose of current work was to characterise the texture, cell-wall polysaccharides and water distribution of grapes pre- and post- high-humidity hot air impingement blanching (HHAIB). The cell-wall pectins nanostructure, water status and distribution of samples were determined by atomic force microscopy (AFM), low field nuclear magnetic resonance (LF-NMR) and magnetic resonance image (MRI), respectively. Results revealed that blanching caused significant berry tissue softening which was accompanied by an increase of water-soluble pectin (WSP, from 39.57 to 57.44 g/100 g fresh weight) and a decrease of chelate-soluble pectin (CSP, from 79.34 to 53.78 g/100 g fresh weight) and sodium-carbonate-soluble pectin (NSP, from 364.23 to 187.64 g/100 g fresh weight) concentration. Obvious depolymerization and degradation was observed in cell-wall polysaccharides nanostructure in blanched berries. The length frequencies of WSP chains are mainly distributed in the range of 0.51-2.00 µm, while it was 1.01-2.00 µm for the CSP chains of blanched samples. LF-NMR transverse relaxation time and MRI analysis indicated that HHAIB treatment resulted in a water loss and migration from berry interior to surface tissue. The findings in present study provide a deeper understanding in tissue softening and moisture variation of blanched berries.

Effect of high-pressure on calorimetric, rheological and dielectric properties of selected starch dispersions.

Effects of high-pressure (HP) treatment on the rheological, thermal and dielectric properties of the four selected starch dispersions (two modified starches, one native and one resistant) were evaluated. Differential scanning calorimetry (DSC) and oscillatory rheometry were employed to assess the extent of starch gelatinization and the developed gel rigidity (G') of starch gels after HP treatment. It was observed that starch dispersions gelatinized completely at 500 MPa with a 30-min holding time. The HP-treated starch samples exhibited predominantly solid-like (G'>G") behavior except for the resistant starch. Pressure-induced gel rigidity differed significantly among starch samples. The G' of starch gels increased with the pressure (400-600 MPa) in the studied frequency range (0.1-10 Hz) except for the native starch where a marginal decrease was recorded at similar condition. The holding time (15-30 min) and concentration (20-25% w/w) significantly attributed towards gel rigidity of starch samples. Measurement of dielectric properties of HP-treated samples over the frequency range 450-4450 MHz indicated differences in the dielectric constant (ɛ'), loss factor (ɛ") and penetration depth among starch gels. Pressure did not show any effect on dielectric property of the resistant starch sample. Power penetration depth decreased significantly with frequency and with the pressure.