Effect of harvesting time and fruit size on titratable acidity, soluble solid and distribution of limonin in Thai tangerine juice

The effect of fruit size and harvesting of Thai tangerine fruit ( Citrus reticulata , Blanco) at different growth stages, 8–12 months after fruit set, on the distribution of limonin in whole fruit as well as in the individual fruit parts and extracted juice was investigated. The highest limonin concentration was observed in seed, followed by albedo, flavedo, segment membrane and juice sacs in decreasing order. The limonin concentration in juice as well as in whole fruit was decreased when fruit was harvested 8–12 months of fruit set. Increasing harvesting time from 8 to 12 months showed corresponding decreases in the amount of limonin in flavedo, albedo and seed. There was a decrease in titrable acidity and increase in total soluble solid and total soluble solid/titrable acidity ratio of juice with a later than normal harvesting time. However, fruit size showed no effect on limonin content and other properties of juice extracted from tangerine.     

Isolation of probiotic bacteria from turmeric (Curcuma longa Linn.) and its application in enriched beverages

The purpose of this study is to obtain lactic acid bacteria (LAB) from fresh turmeric rhizomes that could be used as starter culture with the ability to ferment turmeric and to investigate its influence on total phenolic content (TPC) and antioxidant activity. Three LAB strains, namely Enterococcus faecium, Lactococcus lactis subsp. lactis, and Lactobacillus plantarum, were isolated from turmeric rhizomes. These microorganisms showed similar characteristics as probiotic organisms. The TPC of fermented turmeric beverages was measured using the Folin–Denis reagent method, while the antioxidant activity assays were quantified by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and ferric reducing antioxidant power assay. This study confirms that bacteria isolated from turmeric can be used as starter. Moreover, fermentation time and LAB lead to dominant amount of TPC and that they have high levels of antioxidant activities.     

Effects of parboiling and fluidized bed drying on the physicochemical properties of germinated brown rice

Changes in physicochemical properties of germinated brown rice (GBR) and parboiled germinated brown rice (PGBR) dried in a fluidized bed dryer at 110–150 °C were investigated. Results indicated that parboiling altered the properties of GBR owing to starch gelatinisation. The moisture content, yellowness, peak viscosity and hardness of PGBR increased, but internal fissured kernel, cooking time, water absorption and total solids loss decreased when compared to GBR. γ‐aminobutyric acid (GABA) content in GBR was 23.31 mg per 100 g and was reduced to 17.91 mg per 100 g in PGBR. The drying times required to reduce the moisture content of GBR and PGBR to 16% d.b. were 4.01–7.65 min and 5.11–9.50 min, respectively. Final moisture content, which is optimum to prevent internal fissures of dried GBR and PGBR, was 27–29% and 25–28% d.b., respectively. The same trend was observed in the physicochemical properties of GBR and PGBR when increasing drying temperature and time.     

Effect of rice variety,rice flour concentration and enzyme levels on composite bread quality

A study was conducted to determine the suitability of substituting portions of wheat flours with rice flours for breadmaking. The levels of substitution were 50, 100, 150 and 200 g kg^?1. Two kinds of enzymes, barley malt and fungal amylase, were added to composite flours, and their effects on the volume and quality of the rice-based bread were determined. The results showed that the enzymes, levels of replacement and the varieties of rice had significant effects on weight, specific volume and overall acceptability of the bread samples. However, the enzymes did not have significant effects on the volume, protein and fat contents or on the character and color of the crust in the sensory analysis. Comparisons were made of the nutritional and sensory qualities of the bread made entirely from wheat flour, and the sample which performed best, the bread with 50 g kg^?1 of flour from low amylose variety (183.3 g kg^?1) with barley malt, showed non-significant differences. The overall acceptability of the products showed that it is acceptable to substitute wheat flour with flours generated from rice up to the 150 g kg^?1 replacement level only.     

Effect of extrusion conditions on the physicochemical properties of a snack made from purple rice (Hom Nil) and soybean flour blend

Soy flour was added at levels of 5%, 10%, and 15% of Hom Nil rice flour for extrusion at 190 °C barrel temperature and 350 rpm screw speed. The extruded snack qualities decreased inversely with soy flour. However, product qualities were considered to be optimised when soy flour at 5% was added. The effect of feed moisture content (15, 17, 19 g (100 g)^?1 wb), barrel temperature (150, 170, 190 °C) and screw speed (350, 400, 450 rpm) on physicochemical properties of the snack were then investigated. The physicochemical properties of the product including expansion ratio, density, water absorption index (WAI), water solubility index (WSI) and hardness were evaluated. All properties were related, as linear equations, in terms of feed moisture content, barrel temperature, screw speed with relative correlation (R²) at 0.83–0.94. The snack properties along with consumer acceptance were all highest when the extruded condition were 15 g (100 g)^?1 wb feed moisture content, 170 °C of barrel temperature and 450 rpm of screw speed.     

High-power ultrasonication-assisted extraction of soybean isoflavones and effect of toasting

The effect of high-power ultrasonication (HPU) on extraction of soybean isoflavones and components, including total phenolic and DPPH radical scavenging activities (RSA) were evaluated. Isoflavones from defatted soybean flakes were extracted using a bench scale HPU system at 20 kHz and varying amplitudes (18–54 μm) for 1 and 3 min. Aqueous acetonitrile, and aqueous ethanol based solvents were evaluated for extraction at samples-to-solvent ratios of 0.1:1 and 0.2:1. The non-sonication control extraction was with mixing with magnetic stirrer for 2 h. Preliminary data indicated 1.2–1.5 times more genistein recovery at 1, and 3 min sonication compared to control, however, total phenolic decreased. The genistein recovery was lower at higher sonication levels. RSA also decreased to 40% for HPU-assisted extractions. Total isoflavones recovery in HPU-assisted extractions increased from 600 to 5813 μg/g. The concentration of major isoflavone components, genistein, daidzein, and glycitein also increased by 10-fold. HPU for 3 min reduced the average particle size of treated soy flakes from 530 μm to 60 μm. Toasting at 150 °C of defatted soy flake for longer period of time led to higher aglycone concentration in extract; however, 2 h toasting was sufficient prior to HPU-assisted extraction.     

Ultrasonic assisted alkali extraction of protein from defatted rice bran and properties of the protein concentrates

Alkaline extraction for the preparation of protein concentrate from rice bran was compared with a range of ultrasonic treatments. Results revealed that the extraction time decreased, and the reaction rate constant increased, with increasing ultrasonic power. The reaction rate constants were 0.0065, 0.0130, 0.0237 and 0.0924 at 40, 60, 80 and 100 W respectively. The defatted rice bran protein concentrate (DRBPC) using ultrasonication (100 W for 5 min) and conventional methods showed no significant difference in bulk densities ( P  > 0.05) but it had higher yield (%) and was lighter brown using ultrasonication ( P  ≤ 0.05). The SEM showed that the residual rice bran after extracting protein using ultrasonication exhibited more damage than the conventional method. The functional properties of both samples were not significantly different ( P  > 0.05) in terms of foam and emulsifying stability. However, the water and oil absorption, foam capacity and emulsion activity were significantly different ( P  ≤ 0.05). The nitrogen solubility index of both DRBPC samples gave similar profiles with the lowest solubility at pH 4–6.     

Effect of Raw Material Preparation on Rice Vermicelli Quality

The physicochemical properties of high amylose rice flour prepared from wet milling and dry milling were examined and the rice vermicelli quality made from these flour samples was evaluated. The effect of flour particle size on rice vermicelli quality was also determined. The milling method affected chemical compositions and all physicochemical properties of the flour. A higher degree of starch damage occurred in drymilled flour. Rice vermicelli made from dry‐milled flour had higher cooking losses and softer texture than that made from wet‐milled flour and the commercial reference products. Flour particle size influenced both cooking and textural quality of rice vermicelli but did not influence the water absorption index. Flours with larger particle sizes gave vermicelli with higher cooking loss and less desirable texture than flours with smaller particle sizes. Flour with particle sizes less than 200 mesh produced acceptable vermicelli in terms of cooking and textural quality.