Grain Oil Science and Technology最新文献

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.

The baking quality of sorghum-wheat bread is equally reliant on the quantity and the quality of protein existent in the composite flours. A lot of procedures have been proposed for expanding the use of sorghum either as a composite flour blended with wheat or potentially as a straight flour. In any case, the amount of flour that can be subbed is up to a specific degree of sorghum flour to deliver sensory attractive products. The manipulation of the chemical composition, textural properties of the sorghum kernel, and selection of a proper hybrid could proffer desirable value addition results in bread making. The quality of the flour and the adherence to acceptable flour size standards is the key to producing good quality bread. In this paper, the effects of adding sorghum flour on dough rheological properties and the quality of bread were discussed in detail.

Starch with different particle sizes has different compositions and different physical and chemical properties. The amylopectin content and protein content and lipid content of small granule B starch are higher than that of A-type starch, which can form spiral complex to limit the expansion of starch. Under the same treatment conditions, B-type starch is more vulnerable to damage, sensitive to freezing storage, even breaks in freezing storage, and has higher gelatinization temperature than other starch during freezing. Amylose contained in A-type has high content, high crystallinity, high degree of ordering after frozen storage and insensitivity to frozen storage, which is beneficial to improve the stability of pores and texture of frozen dough. With the extension of freezing time, the content of amylose decreased, while the content of various amylopectin increased and the conformation of polysaccharide changed. Starch deterioration is different under different frozen storage conditions. The deterioration mechanism of frozen dough can be evaluated by variety of starch characteristics during freezing process, which is of great guiding significance to the improvement of frozen dough technology.