Search

Limited data are published regarding changes in the physicochemical properties of rice flours from germinated de-hulled rice treated by ultrasound. This work was undertaken to evaluate the effect of ultrasound treatment (25 kHz, 16 W/L, 5 min) on starch hydrolysis and functional properties of rice flours produced from ultrasound-treated red rice and brown rice germinated for up to 36 h. Environmental Scanning Electron Microscopy (ESEM) microimages showed that the ultrasound treatment altered the surface microstructure of rice, which helped to improve moisture transfer during steam-cooking. The flours from sonicated germinated de-hulled rice exhibited significantly (p < .05) enhanced starch hydrolysis, increased the glucose content, and decreased falling number values and viscosities determined by a Rapid Visco Analyzer. The amylase activity of the germinating red rice and brown rice displayed different sensitivity to ultrasonic treatment. The ultrasonic pre-treatment resulted in a significant reduction in energy use during germination with a potential to further reduce energy use in germinated rice cooking process. The present study indicated that ultrasound could be a low-power consumption method to modify the rheological behavior of germinated rice flour, as well as an efficient approach to improve the texture, flavor, and nutrient properties of steam-cooked germinated rice., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Red rice (Oryza sativa L.) that has a red (reddish brown) bran layer in de-hulled rice is known to contain rich biofunctional components. Germination is an effective technique to improve the nutritional quality, digestibility, and flavor of de-hulled rice. Ultrasonication, a form of physical stimulation, has been documented as a novel approach to improve the nutritional quality of plant-based food. This study was undertaken to test the use of ultrasound to enhance the nutritional value of red rice. Ultrasonication (5min, 16W/L) was applied to rice during soaking or after 66h germination. Changes of metabolites (amino acids, sugars, and organic acids) in red rice treated by ultrasonication were determined using a GC/MS plant primary metabolomics analysis platform. Differential expressed metabolites were identified through multivariate statistical analysis. Results showed that γ-aminobutyric acid (GABA) and riboflavin (vitamin B 2 ) in red rice significantly increased after germination for 72h, and then experienced a further increase after treatment by ultrasound at different stages during germination. The metabolomics analysis showed that some plant metabolites, i.e. GABA, O-phosphoethanolamine, and glucose-6-phosphate were significantly increased after the ultrasonic treatment (VIP>1.5) in comparison with the untreated germinated rice. The findings of this study showed that controlled germination with ultrasonic stress is an effective method to enhance GABA and other health-promoted components in de-hulled rice., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Sprouts and microgreens present unique food safety risks. This study aimed to enhance microbial food safety of sprouts and microgreens via seed sanitation and antimicrobial spray. Radish, broccoli, and kale seeds inoculated with Escherichia coli O157:H7 were sanitized by a high acoustic power density (APD) ultrasound and mild heat (55 °C water) combined treatment for 5 min (US-5) or 10 min (US-10) that was compared with the FDA-recommended 20 min, 20,000 mg/L chlorine treatment. E. coli O157:H7 populations of the seeds and sprouts/microgreens were enumerated immediately after seed sanitation, on day-4 of germination, and after 4 more days in storage, or at the time of harvesting (day 7) for microgreens. Sanitated seeds were planted into germination mix and sprayed with water, 0.1% or 0.2% of calcium oxide (CaO) solution three times a day for 7 days. The US-5 treatment achieved a comparable E. coli O157:H7 reduction and sprout yield as the 20,000 mg/L chlorine treatment. The US-10 treatment exhibited a significantly higher E. coli O157: H7 reduction in all three seed types than the chlorine treatment but with a lower germination rate (p < 0.05). The 0.1% CaO spray effectively inhibited E. coli O157:H7 growth in kale microgreens while maintaining the yield and germination rate. For the same varieties of seeds regardless of treatment, microgreens harvested without roots showed much lower microbial loads (3.0–3.9 log CFU/g) than sprouts (6.0–7.0 log CFU/g) with roots. Overall, the US-5 treatment can be an adequate and environmentally friendly alternative to the traditional chlorine treatment. This study provided a practical solution to ensure microbial safety of the sprouts and presented evidence that microgreens are generally safer than sprouts. • High acoustic power density (APD) ultrasound is effective for surface sanitation. • High APD ultrasound +55 °C water seed sanitation can replace the 20,000-ppm chlorine method. • Seed sanitation efficiency is negatively correlated with seed surface roughness. • Microgreens have lower E. coli concentration in edible parts than sprouts. • Broccoli seed skin was damaged the most during pre-germination treatments. [ABSTRACT FROM AUTHOR]

Limited data are published regarding changes in the physicochemical properties of rice flours from germinated de-hulled rice treated by ultrasound. This work was undertaken to evaluate the effect of ultrasound treatment (25 kHz, 16 W/L, 5 min) on starch hydrolysis and functional properties of rice flours produced from ultrasound-treated red rice and brown rice germinated for up to 36 h. Environmental Scanning Electron Microscopy (ESEM) microimages showed that the ultrasound treatment altered the surface microstructure of rice, which helped to improve moisture transfer during steam-cooking. The flours from sonicated germinated de-hulled rice exhibited significantly ( p  < .05) enhanced starch hydrolysis, increased the glucose content, and decreased falling number values and viscosities determined by a Rapid Visco Analyzer. The amylase activity of the germinating red rice and brown rice displayed different sensitivity to ultrasonic treatment. The ultrasonic pre-treatment resulted in a significant reduction in energy use during germination with a potential to further reduce energy use in germinated rice cooking process. The present study indicated that ultrasound could be a low-power consumption method to modify the rheological behavior of germinated rice flour, as well as an efficient approach to improve the texture, flavor, and nutrient properties of steam-cooked germinated rice. [ABSTRACT FROM AUTHOR]