Grain Oil Science and Technology最新文献

Identifying novel processing methods is an important research direction in the field of food engineering. Fermented flour products have been popular all over the world for a long time because of their unique flavor and texture. Whether for yeast or sourdough, the accurate temperature control is essential for the fermentation process. Some novel heating methods have shown potential in the processing of fermented flour products. Microwave heating (MWH), radiofrequency heating (RFH), and ohmic heating (OH) are undoubtedly the most promising heating methods. MWH affects the fermentation time of the dough by affecting the water molecules in the dough, and may also improve the fermentation quality of whole-wheat flour products. RFH contributes to the control of harmful substances in the fermentation process and has shown potential for the production of sourdough bread. OH has superiority in accurately controlling the temperature, enzymes, microorganisms, etc. in the fermentation process, and it is beneficial to shortening the fermentation time. Researchers have applied these heating methods with different properties to different uses. This article summarized the application and potential of these three novel heating methods in the production of fermented flour products. The application scenarios and parameter settings of novel heating technologies in dough fermentation process need further research. It is reasonable to believe that novel heating methods can become an important tool to improve the efficiency of dough fermentation and the quality of fermented dough in the future.

Benefiting from its favorable effects in promoting intestinal peristalsis, increasing satiety and reducing postprandial blood sugar, wheat bran insoluble dietary fiber (IDF) could be added to noodles to improve the nutrition value of noodle products. However, the addition of IDF usually results in an adverse effect on the quality characteristics of fiber fortified products, leading to unfavorable texture and consumption drop. It was found that IDF could weaken dough characteristics, thereby causing the quality deterioration of noodles, but the mechanism is unclear as yet. This study aimed to investigate the effects of different amounts of IDF on the texture quality and cooking quality of noodles. The water distribution, rheological properties, pasting properties and cooking properties of the noodles were determined by low-field nuclear magnetic resonance (LF-NMR), dynamic rheometer, and rapid visco-analyzer. The results of the LF-NMR showed that the increased IDF in the noodles resulted in a contraction of relaxation time and an increase in the proportion of loosely bound water. At a high amount of IDF, the water absorption and tensile distance of the noodles significantly decreased and the cooking loss rate increased, with a downward trend in peak viscosity, final viscosity and setback values. Moreover, IDF could improve the storage modulus and loss modulus of sheeted dough and enhance the texture of noodles. Furthermore, the correlations between IDF addition amounts and rheological properties as well as cooking properties were analyzed, and the results confirmed that noodles with the IDF amount of 2%–4% had higher nutrition and quality. This study provides the basis for future development and improvement of IDF-enriched health foods.

The prevention of fungal spoilage is an essential consideration in wheat storage. Recent studies have revealed that volatile organic compounds (VOCs), possibly with natural fungicidal properties, could be produced from stored wheat grains. In this study, the antifungal effect of hexanal, a main component of VOCs from stored wheat, against spoilage fungi on agar plate and in high-moisture wheat grains were investigated via the gas fumigation method. And the impact of hexanal fumigation on grain quality was evaluated through analysis of the malondialdehyde content, fatty acid values, germination percentages and vigor of 16% and 18% moisture wheat grains fumigated with 1.66, 2.49, and 3.31 mmol/L hexanal vapor. The results of in vitro antifungal experiments on agar plates revealed that the minimum inhibitory concentration and minimum fungicidal (fatal) concentration of hexanal against the five fungi were 4–14 folds and 4–7 folds lower than those of propionic acid, respectively. The fungal spoilage of high-moisture wheat grains inoculated with pure fungal spores and with naturally occurring fungi could be completely inhibited by 1.66 mmol/L hexanal vapor. During 5-week storage of high-moisture wheat grains fumigated with 1.66, 2.49, and 3.31 mmol/L hexanal vapor, the malondialdehyde content in high-moisture wheat grains did not change significantly in all samples, and fatty acid values were slightly higher in 18% moisture wheat than in 16% moisture wheat. The germination percentages and vigor of wheat samples decreased with increased hexanal vapor concentrations and moisture content. These results indicated that hexanal fumigation could be used as an alternative chemical control method to prevent the fungal spoilage of postharvest wheat.

Phytosterols, which are naturally occurring in plants, have excellent nutritional and health values on lowering both the blood cholesterol level and the risk of cardiovascular diseases. Edible oils are the main source of daily intake of phytosterols, whereas the properties of phytosterols may vary a lot depending on their sources. During the processing of edible oil including refining and frying, phytosterol's content fluctuates, which influences the properties of the final product. Phytosterols and their derivatives undergo physical migration between different phases and chemical conversion during the processing, which reduces the quality and the commercial value of edible oils. Therein, the loss of phytosterols is the major concern in the process of neutralization and deodorization. In addition, oxidation and thermal degradation of phytosterols occur simultaneously during frying, which also reduces the content of phytosterols. Nevertheless, the oil matrix has a promoting or an inhibitory effect on the thermal oxidation of phytosterols. Therefore, various efforts have been devoted to analyzing and improving the remaining contents of phytosterols in edible oil. Regardless of the processing method, temperature plays an important role in the loss of phytosterols. At present, the main analysis methods of phytosterols include gas chromatography and liquid chromatography, in which the pretreatment of different types of phytosterols is also a crucial step. This review focused on the following topics comprehensively: (i) the distribution of phytosterols in the oil-containing plants and edible oils during the refining processing; (ii) the pretreatment and analysis methods of various phytosterols (free phytosterols, phytosteryl fatty acid esters, phytosteryl glycosides and acylated phytosteryl glycosides); (iii) the variation of phytosterols in process of esterification and oxidation, storage and so on. The study also proposed that the investigation in the loss and safety of phytosterols during processing of the vegetable oils should be proceeded further in combination with efficient and accurate chromatography methods.

During the investigation of natural enemy insects in grain depots, we've found an Anthocoridae insect accounted for a high proportion of natural enemy insects. We identify the enemy insects from morphology and molecular biology, so as to realize more accurate and effective control of storage pests by using the enemy insect. The images of the insects under the ultra-depth microscope (VHX-5000) showed that the insect adults were black brown in colour; the antennas of both the female and male had four segments, which increase in length sequentially from the base to the end, and had a length of 756.2 μm for the female and 741.1 μm for the male. The rostrums of both the female and the male insects were composed of three segments, the male's rostrum (596.8 μm) were shorter than the female's (734.6 μm), and the former two segments of the female's rostrum were significantly longer than the male's. The abdomen of the insect was bilaterally symmetrical, the female's abdomen was wider than the male, and the male insect had a dent between its eighth and ninth segments of the left abdomen, in which its male genitalia was located. In addition, the nymphs as a whole were tangerine in colour, and the eggs were elliptic with creamy white gloss and gridding patterns on the surface. The cytochrome C oxidase I (COI)  gene sequences of the insects were identified by DNA barcoding technique, and the determined COI sequences were then submitted to the Genbank database for Blast alignment, and the results showed that the COI gene sequences had a high degree of similarity (99%) with X. flavipes records in the Genbank database. Therefore, we could determine that the insect was X. flavipes. In addition, the neighbor joining (NJ) was used to construct the evolutionary tree, and 1,000 repeated tests were conducted on the confidence levels of each branch. Based on the phylogenetic tree, we've found that X. flavipes belongs to Xylocoris genus. Based on morphology and COI sequence identification, we confidentiy determined that the collected natural enemy insect was X. flavipes. This is the first time that the identification of X. flavipes is being investigated from morphology and molecular biology. The research results are helpful to identify and distinguish the species of flower bugs, and beneficial for the better application of X. flavipes in biological control.

Due to its beneficial health effects, the use of soybean protein has shown a continuous increase, but concerns regarding the allergenicity of soybean antigenic protein have also increased. This study aimed to evaluate the hydrolytic effects of a non-commercial alkaline protease isolated from the Bacillus subtilis ACCC 01746 on soybean β-conglycinin and the allergenicity of its hydrolysates. Alkaline protease of the strain was separated by precipitation method of organic solvents, and the β-conglycinin was separated by alkali-solution and acid-isolation and purified by use of gel column. Using the degree of hydrolysis (DH) and inhibition rate as evaluation indexes, the enzymatic hydrolysis parameters of β-conglycinin was optimized by single factor and L₉(3⁴) orthogonal tests, so as to explore the effect of the protease on the hydrolysis degree and the antigenicity of β-conglycinin hydrolysates. The results showed that the native enzyme existed as an 18.3 kDa monomer with a 430 U/g maximum activity. The purity of β-conglycinin was 84.8%. The single-factor test results showed that DH showed the oppostie trendency with the inhibition rate, and the increase of protein concentration caused monotone increasing and monotone decreasing of the inhibition rate and the DH, and the optimal protein concentration was 30 mg/mL. The optimization results showed that pH had the largest impacts on both DH and the inhibition rate, followed by enzyme dosage, hydrolysis temperature and hydrolysis time. Under the optimum hydrolysis conditions of protein concentration 30 mg/mL, enzyme dosage 0.7%, hydrolysis time 40 min, temperature 55 °C and pH 8.5, the DH reached the highest of 76.28%, and the inhibition rate was the lowest of 27.03%, which was reduced greatly compared with that before optimization. These results suggested that alkaline protease appeared to show a relatively high effeciency in lowering soybean allergenicity, making it possible to produce low-allergenicity soybean protein.

Due to the complexity of structure, it is difficult to determine the content of sorghum tannins. The current method for the determination of sorghum tannins is the Ferric ammonium citrate assay described in ISO 9648. However, the standard tannic acid (TA) used in the ISO 9648 method is significantly different in both structure and dynamics from sorghum tannins, resulting in inaccurate quantitative result. Furthermore, the extraction solvent, 75% dimethylformamide (DMF), used in each step of this method had large toxicity to human. Hence, the objective of this study is to optimize the ISO 9648 method by selecting proper standard and extraction solvents so as to enhance the accuracy and safety. In this study, Sephadex LH-20 chromatography combined with high pressure liquid chromatography was used to purify and identify the extracted sorghum tannin (ST). Then, commercial TA, epicatechin (EA), grape seed procyanidin (PA) were selected as the standard and ST was used as reference for Ferric ammonium citrate assay to compare the effects of the three standards. Furthermore, the extraction rates of sorghum tannins in the presence of several low toxic solvents, such as absolute ethanol, absolute methanol, 70% ethanol solution, 70% methanol solution and 70% acetone solution, were compared to determine the alternative solvents of 75% DMF solution. The results showed that PA was superior to TA and EA in structure, with satisfactory color yield close to ST, and higher accuracy than TA. In terms of the extraction solvent, 70% acetone solution was selected to replace 75% DMF solution because of its higher extraction yield (only next to 75% DMF) and low toxicity. Verification experiment results showed that both the recovery rate and the repeatability of the optimized method met the requirements of AOCO. Moreover, the optimized method, with higher accuracy and safety than the ISO 9648 method, can be applied widely in laboratory.

Water-solid interactions play a key role in determining the efficacy of inert dusts. The critical water activity (A_wc) for phase transition in amorphous materials is an important characteristic of amorphous inert dusts used as grain protectants. As water activity (A_w) rises above A_wc, amorphous dusts undergo a transition from glassy or vitreous state to rubbery state. Such a transition induces dramatic changes in material properties, texture and structure, and hence impact their performance as grain protectants. Full Dynamic Dewpoint Isotherms (DDI) of a synthetic amorphous zeolite intended for grain protection were generated using the Vapor Sorption Analyzer (VSA) to determine A_wc by investigating the relationship between moisture content and A_w at constant temperatures. Sorption experimental data was fitted using three sorption isotherm models: Guggenheim-Anderson-de Boer (GAB), Double Log Polynomial (DLP), and Brunauer-Emmet-Teller (BET). DLP model was the best model to estimate zeolite and wheat sorption isotherms. Full sorption isotherms of zeolite and wheat obtained at 25, 35, and 45 °C clearly showed the hysteresis phenomenon. The hysteresis loops were of type H3 for wheat, and of type H4 for zeolite powder. The intensity of hysteresis remained unchanged for wheat. However, the intensity of hysteresis decreased with increasing temperatures during water adsorption by porous zeolite powder. Monolayer moisture content values for each sorption direction were provided only by GAB and BET models and indicated a decrease in monolayer moisture content with an increase in temperature. The net isosteric heats of sorption and the differential enthalpy of zeolite estimated by the Clausius–Clapeyron equation and determined graphically decreased with increasing moisture content. Conversely, differential entropy of zeolite decreased with increasing zeolite moisture content. The optimal moisture content of inert dust for grain treatment was dependent on wheat moisture content and wheat storage temperature. This is the first time that a synthetic amorphous dust is being investigated for grain protection. Our results recommend the application of inert dusts at the optimal moisture content to mitigate moisture migration within the system “wheat-dust”, thus ensuring dust maximal efficacy.