Effect of gamma irradiation on rice and its food products

Structure-based modification of a-amylase by conventional and emerging technologies: Comparative study on the secondary structure, activity, thermal stability and amylolysis efficiency

α-Amylase is an endo-enzyme that catalyzes the hydrolysis of starch into shorter oligosaccharides. α-Amylase plays a crucial role in various industries. Manipulated α-amylases are of particular interest due to their remarkable amylolysis efficiency and thermostability for large-scale biotechnological processes. The retained catalytic activity of enzymes is decreased according to extreme pH, temperature, pressure, and chemical reagents. Broad industrial applications of α-amylases need special properties such as stability against temperature, pH, and chelators, and also attain reusability, desirable enzymatic activity, efficiency, and selectivity. Considering the biotechnological importance of α-amylase, its high stability is the most critical challenge for its economic viability. Therefore, improving its functionality and stability recently gained much interest. To achieve this purpose, various emerging technologies in combination with conventional methods on α-Amylases with different sources have been conducted. The present review is an attempt to summarize the effect of various conventional methods and emerging technologies employed to date on α-amylase secondary structure, thermal stability, and performance.

Active compounds: A new direction for rice value addition

The development of rice active compounds is conducive to improving the added value of rice. This paper focused on the types and effects of active compounds in rice. Furthermore, it summarized the effect of rice storage and processing technology on rice active compounds. We conclude the following: Rice contains a large number of active compounds that are beneficial to humans. At present, the research on the action mechanism of rice active compounds on the human body is not deep enough, and the ability to deeply process rice is insufficient, greatly limiting the development of the rice active compound industry. To maximize the added value of rice, it is necessary to establish a dedicated preservation and processing technology system based on the physicochemical properties of the required active compounds. Additionally, attention should be paid to the development and application of composite technologies during the development of the rice active compound industry.

Use of Blood Powder (Ground and Irradiated) for the Manufacture of Chocolate Agar

Chocolate agar (CA) is an enriched medium for the isolation and identification of fastidious bacteria. Defibrinated blood is used to manufacture CA, but this expensive product is not always affordable for companies in developing countries. Blood powder (BP) is potentially a cheaper alternative, although its pre-treatment using autoclaving can impair the quality of the media. Therefore, optimization of BP as a substitute for defibrinated blood for CA manufacture deserves further research. CA was manufactured with irradiated BP (dehydrated bovine blood powder) and its physical and microbiological characteristics were compared with those of conventional CA and CA prepared with autoclaved BP. Each medium was seeded with 20-200 CFU of target bacteria using the spiral pouring method. Finally, another medium was prepared using BP pre-treated by grinding and gamma irradiation and its performance assessed. Compared to conventional CA, the medium containing ground and irradiated BP provided a similar CFU count for both fastidious (Neisseria, Haemophilus, Campylobacter, and Streptococcus) and non-fastidious (Moraxella, Staphylococcus, Enterococcus, Klebsiella, and Pseudomonas) species, unlike the medium prepared with BP subjected only to irradiation, which provided a lower growth of fastidious species. Morphology and characteristics of all bacterial colonies were very similar in conventional CA and the new medium, the number of Pseudomonas CFU being higher in the latter. The medium prepared with ground plus irradiated vs. irradiated BP more closely resembled conventional CA, having a browner background. The new CA medium prepared with ground and gamma irradiation-sterilized BP has comparable productivity properties to conventional CA. Therefore, it could be a more practical and economical methodology to facilitate large-scale CA manufacture.

Novel nonthermal food processing practices: Their influences on nutritional and technological characteristics of cereal proteins

Cereals, as the main crops cultivated and consumed in the world, are a rich source of carbohydrates, proteins, dietary fiber, and minerals. Despite the nutritional importance, their technological applicability in food matrices is also considerably important to be determined. Cereal processing is done to achieve goals as increasing the shelf‐life, obtaining the desired technological function, and enhancing the nutritional value. Nonthermal processing is preferred regarding its potential to provide beneficial impacts with minimum adverse effect. Technological functionality and nutritional performance are considered as the most basic challenges through cereal processing, with proteins as the main factor to take part in such roles. Technological and nutritional functionalities of proteins have been found to be changed through nonthermal processing, which is generally attributed to conformational and structural changes. Therefore, this study is aimed to investigate the impact of nonthermal processing on nutritional and technological characteristics of cereal proteins.

Gamma radiation application to rice: Reduced glycemic index in relation to modified carbohydrate observed in FTIR spectra

This study was conducted with a popular, low price Bangladesh rice variety BRRI Dhan 29 with a view to possible carbohydrate modification targeting lower glycemic index using gamma radiation application. Irradiation process (5 and 10 ​kGy ​at a dose rate of 9.74kGy/h) altered amylose content, amylose/amylopectin ratio, swelling power, and solubility index. FTIR spectroscopy confirmed the changed molecular structures due to radiation application. Treatment with a dose of 5 and 10kGy caused increased amylose and amylose/amylopectin ratio significantly (p ​< ​0.02). The highest amylose content was found in 10 ​kGy irradiated rice (30.20%) compared to unirradiated one (17.27%). Gamma radiation caused decreased swelling and increased water solubility in rice powder. These features of carbohydrate amendment in irradiated rice lead to reduced glycemic index as investigated with the in vivo experiments. Therefore, this study suggests gamma-irradiated rice (10kGy) is beneficial for diabetic subjects keeping lower blood glucose levels.

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Radiation processing of rice significantly enhanced amylose content

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FTIR spectrum confirmed the molecular rearrangement in irradiated rice

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Rice treated with gamma radiation at a 10kGy lowered Glycemic index significantly (p ​< ​0.02).

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Gamma irradiated rice having higher amylose content could be recommended for diabetic subjects.

Influence of Electron Beam Irradiation on the Moisture and Properties of Freshly Harvested and Sun-Dried Rice

Moisture content is an important factor that affects rice storage. Rice with high moisture (HM) content has superior taste but is difficult to store. In this study, low-dose electron beam irradiation (EBI) was used to study water distribution in newly harvested HM (15.03%) rice and dried rice (11.97%) via low-field nuclear magnetic resonance (LF-NMR). The gelatinization, texture and rheological properties of rice and the thermal and digestion properties of rice starch were determined. Results showed that low-dose EBI could change water distribution in rice mainly by affecting free water under low-moisture (LM) conditions and free water and bound water under HM conditions. HM rice showed smooth changes in gelatinization and rheological properties and softened textural properties. The swelling power and solubility index indicated that irradiation promoted the depolymerization of starch chains. Overall, low-dose EBI had little effect on the properties of rice. HM rice showed superior quality and taste, whereas LM rice exhibited superior nutritional quality. This work attempted to optimize the outcome of the EBI treatment of rice for storage purposes by analyzing its effects. It demonstrated that low-dose EBI was more effective and environmentally friendly than other techniques.

Characterization of the physical properties of electron-beam-irradiated white rice and starch during short-term storage

Electron-beam irradiation (EBI) is a cold sterilization technology used in the irradiation processing of food, including rice. Herein, the effects of EBI on the swelling power, color, pasting, and sensory properties of white rice after short-term storage were analyzed. Samples were electron-beam irradiated at 0, 2, 4, 6, or 8 kGy and stored at 25 °C or 37 °C for up to 75 days. Results showed that swelling power and major pasting viscosities (including peak, breakdown, and setback viscosities) at both storage temperatures decreased with increased irradiation dose. Negative correlations were also observed between the major viscosities of pasting properties and irradiation dose at both storage temperatures. During sensory evaluation, extremely low scores for rice hardness, appearance, taste, and overall acceptability were obtained for rice subjected to high EBI dose (>4 kGy). However, rice stored at 37 °C showed lower performance than rice at 25 °C in terms of the abovementioned parameters. By contrast, the sensory properties at irradiation doses between 2 and 4 kGy were better than those of the control group at both storage temperatures. All these findings indicated the potential of low-dose (<4 kGy) EBI as pretreatment for improving the quality of white rice during storage.

Gamma irradiation protect the developing wheat endosperm from oxidative damage by balancing the trade-off between the defence network and grains quality

Gamma irradiation has been reported to modulate the biochemical and molecular parameters associated with the tolerance of plant species under biotic/ abiotic stress. Wheat is highly sensitive to heat stress (HS), as evident from the decrease in the quantity and quality of the total grains. Here, we studied the effect of pre-treatment of wheat dry seeds with different doses of gamma irradiation (0.20, 0.25 and 0.30 kGy) on tolerance level and quality of developing wheat endospermic tissue under HS (38 °C, 1 h; continuously for three days). Expression analysis of genes associated with defence and starch metabolism in developing grains showed maximum transcripts of HSP17 (in response to 0.25 kGy + HS) and AGPase (under 0.30 kGy), as compared to control. Gamma irradiation was observed to balance the accumulation of H₂O₂ by enhancing the activities of SOD and GPx in both the cvs. under HS. Gamma irradiation was observed to stabilize the synthesis of starch and amylose by regulating the activities of AGPase, SSS and α-amylase under HS. The appearance of isoforms of gliadins (α, β, γ, ω) were observed more in gamma irradiated seeds (0.20 kGy), as compared to control. Gamma irradiation (0.25 kGy in HD3118 & 0.20 kGy in HD3086) was observed to have positive effect on the width, length and test seed weight of the grains under HS. The information generated in present investigation provides easy, cheap and user-friendly technology to mitigate the effect of terminal HS on the grain-development process of wheat along with development of robust seeds with high nutrient density.

Innovative processing techniques for altering the physicochemical properties of wholegrain brown rice (Oryza sativa L.) - opportunities for enhancing food quality and health attributes

Rice is a globally important staple consumed by billions of people, and recently there has been considerable interest in promoting the consumption of wholegrain brown rice (WBR) due to its obvious advantages over polished rice in metabolically protective activities. This work highlights the effects of innovative processing technologies on the quality and functional properties of WBR in comparison with traditional approaches; and it is aimed at establishing a quantitative and/or qualitative link between physicochemical changes and high-efficient processing methods. Compared with thermal treatments, applications of innovative nonthermal techniques, such as high hydrostatic pressure (HHP), pulsed electric fields (PEF), ultrasound and cold plasma, are not limited to modifying physicochemical properties of WBR grains, since improvements in nutritional and functional components as well as a reduction in anti-nutritional factors can also be achieved through inducing related biochemical transformation. Much information about processing methods and parameters which influence WBR quality changes has been obtained, but simultaneously achieving the product stabilization and functionality of processed WBR grains requires a comprehensive evaluation of all the quality changes induced by different processing procedures as well as quantitative insights into the relationship between the changes and processing variables.

Effects of electron beam irradiation on physicochemical properties of corn flour and improvement of the gelatinization inhibition

The properties and viscosity-reduction mechanism of corn flour irradiated by electron beam have not been understood properly. Here, we investigate the effects of electron beam irradiation (EBI) on the gelatinization and physicochemical properties of corn flour irradiated by 0-5.40kGy of electron beam. The total starch and crude fiber contents of corn flour decreased significantly (P<0.05) after EBI treatment, while the moisture and reducing sugar contents increased significantly (P<0.05). EBI caused perforations on the corn flour particle surfaces, and the irradiated parts of the particles would gradually peel off and afford smooth surfaces, spherical structures, and smaller sizes. Molecular chains of corn flour broke owing to EBI. After irradiation, the pasting peak viscosity decreased dramatically (P<0.01) from 1251.74 to 7.16Pa·s, showing that the gelatinization of corn flour was completely inhibited. Thus, EBI can be used to inhibit the gelatinization of corn flour, which may be beneficial for industrial and food formulations.

Changes in Physicochemical, Structural, and Sensory Properties of Irradiated Brown Japonica Rice during Storage

Brown japonica rice was treated with (60)Co γ irradiation at doses of 0, 0.2, 0.5, 1.0, and 2.0 kGy immediately after harvesting. The effects of irradiation on physicochemical, structural, and sensory properties during long-term storage (18 months) were investigated. The study revealed that the pasting properties, including peak, through, breakdown, final, and setback viscosities, decrease considerably in a dose-dependent manner and vary differently during 18 months of storage. Irradiation reduced the free fatty acid (FFA) content in comparison with unirradiated brown rice with long-term storage (from 12 to 18 months). Scanning electron microscope (SEM) observation showed that the mean range and shape of starch granules did not vary significantly. However, dark spots developed among starch granules and the narrow cracks became wider with increasing irradiation dose and storage time. During sensory evaluation, extremely low scores for odor and overall acceptability were obtained for medium-dose irradiated rice (1.0 and 2.0 kGy); however, no significant difference was found in acceptability between low-dose irradiated rice (0.2 and 0.5 kGy) and the control rice (0 kGy). Overall, low-dose (0.5 kGy or below) irradiation seems to be a promising alternative treatment to increase brown rice shelf life, without affecting the physicochemical and structural characteristics and sensory acceptability.