Effect of starch multi-scale structure alteration on japonica rice flour functionality under infrared radiation drying and storage

Effects of cold plasma pretreatment before different drying process on the structural and functional properties of starch in Chinese yam

This article compared the effects of hot air drying (HAD), infrared drying (IRD), and cold plasma (CP) as a pretreatment on the structure, quality, and digestive characteristics of starch extracted from yam. As the most commonly used drying method, HAD was used as a control. SEM and CLSM images showed that all treatments preserve the integrity of the yam starch. CP caused some cracks and breaks in the starch granules. IRD did not destroy the crystal structure of starch molecules, but made the spiral structure tighter and increased short-range orderliness. However, CP led to the depolymerization and dispersion of starch molecular chains, resulting in a decrease in average molecular weight and relative crystallinity. These molecular conformation changes caused by different processes led to differences in solubility, swelling power, pasting parameters, digestion characteristics, and functional characteristics. This study provided an important basis for the reasonable drying preparation and utilization of yam starch.

Effects of annealing temperature and time on the structural and physicochemical properties of sweet potato flour hydrogels

The physicochemical properties of sweet potato flour (SPF) can be modified by annealing. Native SPF was annealed in deionized water at a flour-to-water ratio of 1:3 (w/v) and temperatures of 50, 55, 60, or 65 °C for either 12 or 24 h. Annealed SPF maintained the A-type crystalline region and displayed increased relative crystallinity, increased pasting temperature, and decreased breakdown. SPF gels showed enhanced hardness together with better springiness when SPF was annealed at low temperature/long time or high temperature/short time. Annealed SPF hydrogel sheets contained larger, more uniform, and smoother pores than native ones. Noticeably, hydrogel sheets made of SPF annealed at 50 °C for 24 h exhibited advanced fracture strain from 93% to 176%. Overall, this work showed that annealing could modulate the characteristics of SPR hydrogels, which may widen the extent of applications in food industries. However, the annealing conditions need to be optimized.

Influence of accelerating storage of foxtail millet on the edible and cooking quality of its porridge: An insight into the structural alteration of the in-situ protein and starch and physicochemical properties

This study aimed to elucidate the effect of the accelerating storage (40 °C, 10 weeks) of foxtail millet on the edible and cooking quality of its porridge. The structural alteration of the in-situ protein and starch in foxtail millet, as well as the physicochemical properties were investigated. Both the homogeneity and palatability of millet porridge were significantly improved after 8-week storage of millet, while its proximate compositions remained unchanged. Meanwhile, the accelerating storage increased the water absorption and swelling of millet by 20 % and 22 %, respectively. The morphological studies (using the SEM, CLSM and TEM) revealed that the starch granules in the stored millet became easier to swell and melt, leading to better gelatinization with a higher coverage extension in protein bodies. FTIR results showed that the protein hydrogen bonds in the stored millet became stronger and the starch ordered degree was reduced. Compared to the native foxtail millet, the peak, trough, final, and setback viscosity of the stored sample increased by 27 %, 76 %, 115 % and 143 %, respectively, while the onset, peak, and conclusion temperature increased by 0.80, 1.10 and 0.80 °C, respectively. Besides, the G' and G″ of the stored foxtail millet were significantly higher than its native counterpart.

Analysis of microwave irradiation on the lethal conditions for insect pest in rice and its influence and regulation on the quality of rice

In view of the problem that conventional insecticidal methods cannot inhibit the hatching of insect eggs in rice, microwave heating was used to kill the insect eggs hidden in the rice grains. The lethal conditions of microwave irradiation on insect pests in rice and the effects of microwave irradiation on the quality of rice were studied, and the process conditions that can both ensure the quality of rice and kill insects were put forward. The microwave energy density parameter was used to evaluate the lethal conditions of microwave irradiation for insect pests in rice. The results showed that the lethality ratio of insect pests was 100% when the microwave energy density was higher than 0.0325 kW h/kg. Both microwave power density and microwave power affected the quality of rice. The results concluded that the cracking ratio, chalkiness and amylose content were increased with the increase of microwave power at the same microwave power density, while the free fatty acid content was decreased. Through the study of variable microwave power process, it was found that the cracking ratio and chalkiness can be controlled below 1.5% when the heating rate of rice at the later stage of microwave irradiation was less than 0.2 °C/s. The use of two-stage variable microwave power process can eventually ensure the disinfestation and the quality of rice simultaneously.

Superheated steam processing of cereals and cereal products: A review

The concept of superheated steam (SS) was proposed over a century ago and has been widely studied as a drying method. SS processing of cereals and cereal products has been extensively studied in recent years for its advantages of higher drying rates above the inversion temperature, oxygen-free environment, energy conservation, and environmental protection. This review provides a brief introduction to the history, principles, and classification of SS. The applications of SS processing in the drying, enzymatic inactivation, sterilization, mycotoxin degradation, roasting, and cooking of cereals and cereal products are summarized and discussed. Moreover, the effects of SS processing on the physicochemical properties of cereals and the qualities of cereal foods are reviewed and discussed. The applications of SS for cereal processing and its effects on cereal properties have been extensively studied; however, issues such as the browning of cereal foods, thermal damage of starch, protein denaturation, and nutrition loss have not been comprehensively studied. Therefore, further studies are required to better understand the mechanism of the quality changes caused by SS processing and to expand the fields of application of SS in the cereal processing industry. This review enhances the understanding of SS processing and presents theoretical suggestions for promoting SS processing to improve the safety and quality of cereals and cereal products.

Effects of infrared heating as an emerging thermal technology on physicochemical properties of foods

Infrared (IR) radiation is part of an electromagnetic spectrum between the ultraviolet and microwave regions. IR radiation impacts the surface of the food, generating heat that can be used as an efficient drying technique. Apart from drying, IR heating is an emerging food processing technology with applications in baking, roasting, microbial inactivation, insect control, extraction for antioxidant recovery, peeling, and blanching. Physicochemical properties such as texture, color, hardness, total phenols, and antioxidants capability of foods are essential quality attributes that affect the food quality. In this regard, the main objective of this review study was to highlight and discuss the effects of IR heating on food quality to expand its food applications and commercial adoption. The fundamental mechanisms, type of emitters, and IR processing parameters are discussed in this review to explore their impacts on food quality. Infrared heating has been shown that the appropriate operating conditions (distance, exposure time, IR power, and temperature) with high heat transfer, thus leading to a shorter drying time. Besides, IR heating used in food processing to improve food-surface color and flavor, it also enhances hardness, firmness, shrinkage, crispiness, and viscosity. Meanwhile, antioxidant activity is enhanced, and some nutrients are retained.

Sustainable Hydrogen Production from Starch Aqueous Suspensions over a Cd0.7Zn0.3S-Based Photocatalyst

We explored the photoreforming of rice and corn starch with simultaneous hydrogen production over a Cd0.7Zn0.3S-based photocatalyst under visible light irradiation. The photocatalyst was characterized by UV–vis diffuse reflectance spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The influence of starch pretreatment conditions, such as hydrolysis temperature and alkaline concentration, on the reaction rate was studied. The maximum rate of H2 evolution was 730 μmol·h−1·g−1, with AQE = 1.8% at 450 nm, in the solution obtained after starch hydrolysis in 5 M NaOH at 70 °C. The composition of the aqueous phase of the suspension before and after the photocatalytic reaction was studied via high-performance liquid chromatography, and such products as glucose and sodium gluconate, acetate, formate, glycolate, and lactate were found after the photocatalytic reaction.