Grain Oil Science and Technology最新文献

The harm of Aspergillus flavus (A. flavus) and aflatoxin is a severe food safety problem worldwide, which causes huge economic losses every year. Therefore, it is urgent to control the growth of A. flavus and the biosynthesis of aflatoxin. Plant-derived natural compounds are superior to synthetic fungicide in inhibiting the growth of A. flavus benefiting from their high safety to the environment, humans and stock, and low cost. This study aimed to evaluate the antifungal effects and potential antifungal mechanisms of three plant-derived compounds (octanal, nonanal and decanal) against A. flavus. We determined the minimum inhibitory concentrations (MICs) and action mechanism of the three volatile aldehydes on A. flavus and also performed calcofluor white (CW) staining for visualizing the distribution of septa. Cell respiration metabolism and the pathogenicity on maize kernels were also carried out to evaluate the efficacy of the three volatile aldehydes on the growth of A. flavus. The results showed that the three volatile aldehydes could inhibit the germination of spores and mycelial growth of A. flavus, the MICs on spores and mycelia were: octanal (1.0 and 0.5 μL/mL), nonanal (0.5 and 2.0 μL/mL), and decanal (1 and 5 μL/mL). The three volatile aldehydes could strongly damage the integrity of both the cell wall and the cell membrane of A. flavus. Meanwhile, they could decrease the content of total lipid and inhibit respiration metabolism of A. flavus cell. Results of in vitro antifungal test showed that all the three volatile aldehydes could effectively prevent the growth of A. flavus on maize kernels. The study revealed that octanal, nonanal and decanal could effectively inhibit the growth of A. flavus both in culture medium and on maize kernels to different extent. The results confirmed that the plant-derived compounds could be developed into promising antifungal agents applied in the preservation of grains. This study provides a theoretical basis for the research and application of potential antifungal agents.

β-Conglycinin, the main protein of soybean, is a key allergen that causes soybean allergies, and hydrolysis is usually applied to lower its antigenicity. We evaluated the enzymolysis characters of β-conglycinin from the perspective of enzymolysis kinetics using alkaline protease from B. subtilis ACCC 01746. A dynamic model describing the hydrolysis of β-conglycinin was proposed using the initial substrate concentration, enzyme dosage (enzyme to substrate ratio) and hydrolysis time as variables to illustrate the kinetic behavior of enzymatic hydrolysis. The hydrolysis of soybean β-conglycinin was carried out at 60 g/L protein concentration, 0.6% enzyme dosage, 55 °C and pH 8.5 to observe the peptides with anti-enzymatic activities. The hydrolysates were gradually fractionated by ultrafiltration through cut-off membranes with molecular weights of 40, 30, 20, and 10 kDa, and their antigenicities were evaluated using indirect competitive enzyme-linked immunosorbent assay. The results showed that the degree of hydrolysis (DH) of β-conglycinin decreased as the β-conglycinin concentration (S₀) increased, but increased with enzyme dosage (E₀) increasing. Thus, the enzymatic hydrolysis of β-conglycinin followed the first-order kinetics model. The hydrolysis rate (V) was (527.89C_E0–2.5533C_S0) exp (–0.022DH), the DH-hydrolysis time was 45.454ln[1 + (11.614C_E0/C_S0–0.0562)t], and the correlated kinetic constants k₂ and k_d were 527.89 min⁻¹ and 8.6126 min⁻¹, respectively. The hydrolysis behavior of β-conglycinin varied considerably among the α', α, and β subunits. Faster hydrolysis rates were observed for the α' and α subunits compared to the β subunit. The relative molecular weights of the intercepted peptides from the hydrolysates were 14.8–40.1 kDa, and the antigenicity of the peptides with smaller molecular weight was reduced, but not removed completely. However, the alkaline protease from the strain appeared to effectively reduce the allergenicity of β-conglycinin. Therefore, it is possible to produce less allergenic soybean proteins using enzymatic hydrolysis. Additionally, the microbial alkaline protease may serve as a potential novel food enzyme and should be evaluated for the development of hypoallergenic foods.

Argan oil is most frequently sold as pure oil, which can be directly applied topically due to its cosmetological proprieties or ingested in order to provide several health benefits. It's also commonly mixed into a number of cosmetic products like shampoos, soaps and conditioners. In this study we aimed to improve the argan oil extraction yield and quality parameters by comparing the effects of different extraction technologies. Argan kernel oils were extracted using four methods: mechanical cold press, Soxhlet extraction with n-hexane, supercritical fluid extraction (SFE), and enzyme assisted extraction with three different enzyme solutions cellulase (cellulast), pectinase (Pectinex) and a mixture of carbohydrase enzymes (Viscozyme®). The quality parameters was evaluated by determining the acid, peroxide and iodine values as well as the extinction coefficients K₂₃₂ and K₂₇₀ as measures of conjugated dienes and trienes, respectively. The results showed that the highest yield (66.37% ± 3.3%) was obtained by enzyme assisted extraction using the carbohydrases enzymes mixture (Viscozyme®), followed by Soxhlet extraction (59.5% ± 3.1%) and pectinase extraction (52.03% ± 3.55%). All argan oils samples obtained by the different methods showed a good oxidation stability, with acid, peroxide and iodine values lower than 0.8 mg/g, 15 meq/kg and 110 g/100 g according to the official argan oil norm, respectively. The results of argan oils quality parameters demonstrated that the enzyme extracted argan oils showed low oxidation, with the following quality parameters: acid values (0.4–0.6 mg/g), iodine values (95–100 g/100 g), dienes (K₂₃₂ < 2), trienes (K₂₇₀ < 0.35), and peroxide values (<1.5 meq/kg). The results proved that the enzyme assisted extraction method can be applied to improve the argan oil yield without affecting the oil quality. The enzyme extraction method may be a great alternative to solvent and cold press extractions for this eco-friendly processing approach.

Knowing that flavored products would increase the use of olive oil by non-traditional consumers and enhance the added value of this valuable agricultural product, the virgin olive oil (VOO) was flavored with the seeds of Pimpinella anisum (Green anise) using three different methods: classic maceration, ultrasonic assisted maceration and direct addition of the essential oil (EO). These methods were compared under two main criteria: time and level of aromatization. The physico-chemical parameters and the thermal stability of flavored oils prepared by the three methods were determined by AOAC titration method and GC–MS analysis so as to compare the aromatization effect of the three methods. The trans-anethole is the major component of the EO of anise seeds as well as the indicator of the level of aromatization. GC/MS analysis results of the flavored oils showed that the diffusion of trans-anethole in the flavored oil by direct addition of EO was very important (36.3% of the total volatile fraction of the flavored oil) in comparison to the oil flavored by ultrasonic assisted maceration or classic maceration (respectively 26.59% and 23.85%). These different aromatization methods ensure an improvement in the quality of VOO with an enrichment in polyphenols estimated at 35% in the case of ultrasonic flavored oil, an increase in the content of carotenoids and chlorophylls (67% and 21% respectively) in the event of aromatization by classic maceration, and a decrease in specific absorbency at 232 nm estimated at 29% during aromatization by addition of EO as well as a decrease in the peroxide value estimated at 26% in oil flavored by classic maceration unlike in oil flavored by ultrasound which has seen an increase of around 20%. The aromatization was able to maintain the stability of the oils and its qualification as VOO with a gain in induction time in the case of treatment at 60 °C estimated at 29 and 27.5 d respectively in oils flavored by addition of EO and by conventional maceration, an improvement resistance to degradation concerning K₂₃₂ and K₂₇₀ of all flavored oils which varied from 15 to 40 d in the case of treatment at 60 °C and 3 h resistance to degradation of oils treated at 130 °C for K₂₃₂. Polyphenols, chlorophyll pigments and carotenoids play an important role in oxidative stability due to their antioxidant nature and their degradation during heating is very complex. All of these physico-chemical changes have increased the thermal stability of flavored oils with better resistance to oxidation of flavored oil by classic maceration in compared to oil flavored by adding EO and the oil flavored by using ultrasound.

Corn is a high starchy cereal crop with the highest production and provides over 85% of the starch produced worldwide. Various by-products, differentiated by technological process features such as steep liquor, corn germ, corn bran, gluten, are created largely during corn starch processing. They are inexpensive, nutrient-rich, and vary widely in chemical composition such as proteins, oils, carbohydrates, and minerals. In an increasingly resource-constrained modern world, the utilization approach of these by-products for non-starch industrial processing is attractive widely considering both nutritive value and economic aspects. In fact, at present, applications of these by-products can often be found in feed, fermentation, nutrient extraction and other industries. For example, protein-rich corn gluten can be used as a good animal feed, and corn germ can be used as a raw material for the high-quality edible oil industry. Undoubtedly, increasing utilization means that these by-products will no longer be treated as waste but will be transformed into high value-added products. In this work, the separation process and chemical composition of several main by-products of the corn starch industry is briefly described, and the application in many industrial fields of these by-products over the last ten years are discussed in particular. This review attempts to summarize all aspects of the application and research of these by-products. For the by-products of the corn starch industry, the most promising way is to be utilized in high value and used to produce high value-added products. According to the characteristics of their chemical composition, they have a better application prospect and research significance in the industries directly related to human beings, such as medicine, green food and health care products. In fact, in recent years, some researchers have recognized this and carried out the research. It is clear from these studies that the main issues to be faced now and in the future are how to produce efficiently while maintaining the quality of the product and using it effectively. The retrospective discussions also provide some ideas for other grain and oilseed crops to be fully utilized.

To study the structure-antifungal activity of vanillin against Aspergillus flavus (A. flavus), the susceptibilities of A. flavus to vanillin and its isomers (o-vanillin, 2-hydroxy-4-methoxybenzaldehyde (HMB), 2-hydroxy-5-methoxybenzaldehyde) and the possible antifungal mechanisms have been investigated. All the four volatile aldehydes could inhibit the germination of spores, and the minimum inhibitory concentrations (MICs) of them were in this order: vanillin (200 μg/mL), o-vanillin (100 μg/mL), 2-hydroxy-5-methoxybenzaldehyde (100 μg/mL), HMB (70 μg/mL). The minimum fungicidal concentrations (MFCs) of them were in this order: vanillin (240 μg/mL), o-vanillin (160 μg/mL), HMB (140 μg/mL), 2-hydroxy-5-methoxybenzaldehyde (140 μg/mL). Spore size was arrested at 0 h with the treatment of the four volatile aldehydes. Effects of the four volatile aldehydes on the cell wall and cell membrane integrity of A. flavus were observed by calcofluor white (CW) staining and propidium iodide (PI) staining. The results showed that HMB exerted the strongest antifungal and fungicidal effects on the growth of A. flavus. The four volatile aldehydes had little influence on cell wall integrity after 3-hour treatment, however, they could strongly damage the cell membrane integrity. All the four volatile aldehydes could effectively prevent the growth of A. flavus on peanut seeds. The antifungal mechanisms of the four volatile aldehydes provide theoretical foundations for their development of new antifungal agents.

Tibetan butter (TB), generally called butter, is a solid oil product extracted from yak milk in the Qinghai-Tibet plateau area. However, due to the limitations of raw material sources and production technology, there is a shortage of TB, so it is important to find substitutes of TB. This paper studied the crystallization behavior of six kinds of commercial TB products in Tibet to provide the theoretical basis for the development of TB substitutes for the production of TB lamps and flowers. This study assessed the crystallization behaviors of the TB samples, including isothermal crystallization process and non-isothermal crystallization process. The microstructure, isothermal crystallization of TB were evaluated by polarized light microscopy and low-pulse NMR spectrometry, respectively. The non-isothermal crystallization process of TB under temperature scanning were investigated using Rheometer, and the crystallization behavior under different cooling rates were determined by differential scanning calorimetry (DSC) procedures. The results showed that the TB was crystallized at a higher supercooling (−10, 0 and 10 °C). Dimensional growth is dominant; at 20 °C, spiral growth dominates. The TB has complex crystallization nucleation behavior. The crystal types of TB are mainly β'-crystal form and β'-like crystal form. The lower the cooling rate, the shorter the crystallization induction time, and the more the number of crystal nuclei. Therefore, during producing TB substitutes in the factory, the cooling rate can be controlled at 10 °C/min to reduce energy consumption and production costs.

Simiao rice is a variety of long-grain Indica rice popular in South China. However, researches on the milling technology of Simiao rice are limited. The effect of different degrees of milling (DOMs) of Simiao rice (0–12%) were evaluated in terms of the physicochemical properties and in vitro starch digestibility of the rice. The results showed that, as the DOM increased from 0 to 12%, the head rice yield (HRY) and the content of protein, lipid, dietary fiber, vitamin B₁, vitamin E and niacin nonlinearly decreased, while the content of total starch and amylose and paste viscosity parameters nonlinearly increased. The differences in chemical constituents between the brown and milled Simiao rice with different DOMs lead to the variation in their pasting properties and in vitro digestibility. Because of lower content of slowly digestible starch (SDS) and resistant starch (RS), milled Simiao rice exhibited greater digestibility and a higher estimated glycaemic index (EGI). The EGI of Simiao rice ranged from 77.98 to 85.55, and remained almost constant (approximately 84) when the DOM was above 4%. Correlation analysis indicated that the EGI had strong negative correlations with lipid, protein, dietary fiber and RS, but a positive correlation with amylose. These results provide theoretical guidance for the production of Simiao rice with desired physicochemical properties and digestibility by adjusting the DOM.

The γ-PGA-based food hydrogel exhibits good biodegradability and biocompatibility, and is non-toxic to humans. In this study, a novel hydrogel (γ-PGA/casein composite hydrogel) was prepared by combining casein with γ-PGA separated from natto using microbial transglutaminase (MTG) as the crosslinker. The effects of the MTG mass concentration, gelation time, crosslinking temperature, pH, and the mass ratio of γ-PGA to casein on the crosslinking ratio of γ-PGA and swelling ratio of the γ-PGA/casein hydrogel were investigated. Furthermore, the synthesis conditions were optimized by response surface methodology to optimize three important factors, i.e. crosslinking temperature, pH and the mass ratio of γ-PGA to casein. The results of single factor experiments showed that the MTG mass concentration and crosslinking time had little impacts on the crosslinking ratio of γ-PGA and the swelling ratio; the preferred MTG mass concentration, crosslinking time, temperature and pH were selected as 0.3%, 7 h, 40 °C and 7.5; and the preferred mass ratio of γ-PGA to casein was 0.1 for the crosslinking ratio of γ-PGA and 0.2 for the swelling ratio. The response surface experiment results showed that the optimum crosslinking temperature, pH and the mass ratio of γ-PGA to casein ratio were 42.4 °C, 7.33, and 0.18, respectively. Under these optimum conditions, the predicted crosslinking ratio of γ-PGA and swelling ratio reached 90.35% and 112.07%, which were highly consistent with the experimental values (88.00% and 115.87%). The γ-PGA/casein composite hydrogel developed in this study shows promising application potential in food industry, biomedical field, and cosmetic industry.