Guardianelli, LucianoPuppo, Maria C.Salinas, Maria, V
9页
查看更多>>摘要：The objective of this work was to study the effect of pistachio by-product flour (PBF) addition to wheat flour on the rheological properties of dough. Pistachio levels used were: 0 (C), 5 (P5), 15 (P15), and 25 g/100 g (P25). Alveographic and farinographic assays, gluten, moisture content (H), and dough pH were studied. In addition, texture profile analysis, dynamic rheology and relaxation of dough were performed. The farinographic water absorption, development time, and stability decreased with PBF, whereas the degree of softening increased. Moreover, tenacity, extensibility, and deformation work decreased with PBF. Wet gluten (WG) content was not modified, while dry gluten (DG) increased with the PBF level, decreasing the WG/DG ratio. C dough had higher moisture and pH than dough with PBF, and both parameters decreased when PBF content increased. P5 dough was softer and less consistent but with similar adhesiveness and elasticity to C. Dough hardness and elasticity increased with an increase in PBF content. The elastic moduli also increased, while relaxation times were not significantly modified with higher amounts of PBF. The study of hydration and rheological properties of pistachio-wheat dough is important from the technological point of view because pistachio components could affect the final bread quality.
查看更多>>摘要：Solid particles play very important roles in stabilizing Pickering emulsions and improving interfacial catalytic reactions. In this study, hydrophobic modified Fe3O4@SiO2 particles were constructed and used to deacidify rice bran oil (RBO) in enzyme-Pickering emulsions as emulsifiers in the presence of lipase. The results showed that the particles had a core-shell structure with a zeta potential of -24.2 mV, an average particle size of 282.4 +/- 1.30 nm, a contact angle of 83.8 degrees, and a rough surface. Optimal Pickering emulsion stability was achieved by an Fe3O4@SiO2 particle concentration of 1.0 g/100 mL, oil/water ratio of 4:6, homogenization speed of 20,000 rpm and temperature of 50 degrees C. The saturation magnetization value of the emulsifier decreased from 28 emu/g to 5.8 emu/g after 15 reuses. Fluorescence microscopy results revealed that lipase was adsorbed at the oil-water interface when 10 mL/100 mL lipase was added to the continuous phase, which indicated the formation of an enzyme-Pickering emulsion. The enzyme-Pickering emulsion catalytic system was distinguished by a short reaction time (6 h) and good reusability of lipase after 12 reuses (relative activity of 72%) in the deacidification process of RBO. These findings provide a theoretical basis for enzyme-Pickering emulsion application in a magnetic fluidized bed.
查看更多>>摘要：A novel fusion levansucrase (TPS-SacB-T305A) was constructed by adding to SacB-T305A an extra C-terminus of the trehalose-6-phosphate synthase (TPS) involved in its thermostability. The fusion TPS-SacB-T305A was expressed in Escherichia coli and purified, its hydrolytic V-max and K-m were about 39.53 mu mol/(minute*mg protein) and 13.36 mmol/L, respectively. The levan production reached 71.6 +/- 2.06 g/L with a conversion yield of 35.8 +/- 1.03% using sucrose as substrates under the present optimum condition of polymerization and the products were characterized by NMR and FT-IR. Interestingly, the optimum temperature of fused TPS-SacBT305A was 15 degrees C higher than that of free SacB-T305A on levan polymerization, and the half-life at 40 degrees C of fusion enzyme increased to more than 4-fold. The proportion of high molecular weight (HMW) levan (approximately 2000 kDa) to total polysaccharides was raised tremendously from approximately 4% (catalyzed by free SacB-T305A) to approximately 91% (catalyzed by TPS-SacB-T305A). The present study provides a potential industrial enzyme to produce HMW levan and helps to explore the mechanism of levan polymerization.
Siaw, Michelle OppongWang, Ya-JaneMcClung, Anna M.Mauromoustakos, Andy...
9页
查看更多>>摘要：The physicochemical properties of rice are influenced by their chemical components and their interactions. It has been demonstrated that the interactions among rice chemical components are enhanced by protein denaturation (PD) via heat treatment and by lipid removal (LR) via solvent extraction. The objective of this study was to investigate the impacts of PD, LR, and their combined treatments on the gelatinization and pasting properties, swelling power, and water solubility of four brown rice flours. Rice protein was denatured under a vacuum at 100 degrees C, and rice lipid was removed via hexane for varying times. The combined treatments were done in two ways, PD followed by LR (PD-LR), and LR followed by PD (LR-PD). The results showed that PD increased gelatinization temperatures, while LR decreased gelatinization temperatures. Both PD and LR reduced pasting and swelling properties; however, PD resulted in a greater decrease than LR. Polar lipids are proposed to serve as bridges to link denatured proteins and starch granules in the combined treatments, resulting in greater decreases in the pasting and swelling properties than the individual treatments. The results obtained in this study demonstrate the importance of starch-lipid-protein interactions on the physicochemical properties of brown rice flour.
查看更多>>摘要：Wheat starch and proteins functionality can be modified by applying heat moisture treatment, giving beneficial effects on flour technological properties and final product digestibility. The aim of this study was to optimize the conditions of wheat flour hydrothermal treatment (HMT) and the supplementation level with grape peels flour (GPF) and to characterize the optimum product. The effects of the independent variables (temperature, time, moisture level and GPF addition level) on flour viscosity, dough complex modulus and cohesiveness, pasta color, fracturability, polyphenols and dietary fibers contents, cooking loss, chewiness and resistant starch content were investigated. The optimum processing conditions and GPF level were found to be 64.35 degrees C, 3 h and 26.65% moisture for wheat HMT and 4.94% GPF supplementation. The results revealed that the polyphenolics, dietary fiber and resistant starch contents increased compared to the control. Dough complex modulus and pasta fracturability were higher than those of the control, while for chewiness lower value was observed. Protein and starch structural changes caused by HMT were observed by FT-IR and microstructure analysis. These results evidenced the opportunity to use HMT and GPF for pasta production, without significant negative effects on the quality and with many health benefits.
查看更多>>摘要：An orifice based hydrodynamic cavitation system was developed for treating fresh sugarcane juice, non-thermally. The effect of hydrodynamic cavitation treatment parameters such as pressure (2.5, 3, and 3.5 bar), processing time (10, 20, 30, 40 min), and type of orifice plate geometry on the physicochemical attributes such as temperature rise, pH, titratable acidity (TA), total soluble solids (TSS), viscosity, change in colour and microbial load of the sugarcane juice were investigated. The maximum rise in temperature during the treatment was 22 degrees C at 3.5 bars with the 17 number of orifices. The pH decreased from 4.94 to 4.64 and TSS significantly reduced (p < 0.01) from 20 to 13 degrees Brix depending on the severity of the treatment. The reduction in viscosity was in the range of 3-48%. The maximum colour change in the juice could be observed when treated at an inlet pressure of 3.5 bar for a processing time of 40 min with a plate having 17 numbers of orifices. The maximum microbial load inactivation from 5.53 log(10) CFU/mL to 3.3 log(10) CFU/mL was observed at the highest pressure, processing time, and orifices.
查看更多>>摘要：An untargeted GC-MS approach was performed to study the stability of the volatile fraction and taste of five different single-cultivar strawberry purees during pasteurization (95 degrees C/1 min) and accelerated storage (14 d at 35 degrees C). The PLS-DA results showed that the volatile fraction varied markedly among the cultivars in fresh purees; with Honeoye and Sengana exhibiting the most distinctive profiles with more than 8 discriminative markers. However, the differences among the five cultivars remained similar upon pasteurization and storage. Pasteurization generally resulted in changes on the volatile fraction, that could be cultivar dependent, and decrease in glucose and fructose. The contents of hexanal, alcohols and some esters decreased whereas acetate esters increased. During storage, losses of esters, alcohol terpenes, hexanal and the formation of off-flavors (e.g. dimethyl sulfide, alpha-terpineol and hydrocarbons) occurred for all cultivars, whereas sugar contents remained constant. Food manufactures should pay attention to an adequate raw material selection as the strawberry cultivar strongly influences the volatile fraction and taste of the resulting puree after pasteurization and during storage.
查看更多>>摘要：The aim of this study is to isolate and characterize potential aroma producing lactic acid bacteria with some probiotic properties from artisanal cheese environment. For this purpose, 40 of lactic acid bacteria isolates were obtained from traditionally produced White cheese samples. They were preliminary characterized in Enterococcus genus by morphological, physiological, biochemical tools. Technological properties such as milk acidifying, lipolytic and proteolytic activities were also screened. Most of them were good acid producers. Aroma producing ability was determined by diacetyl production and among 40 isolates, 18 of them could produce this compound. DNA isolation and 16 S rRNA ribosomal gene sequence analysis of selected isolates indicated that they were identified as E. faecium, E. faecalis and E. durans. Aroma producers were screened for their probiotic characteristics and they showed variable acid tolerance, hydrophobicity, auto-aggregation, antimicrobial activity and antibiotic sensitivity. All of them tolerated bile salt. In conclusion, particularly two isolate, MD 30 and MD 38 identified as E. faecium were found to be the most promising bacteria due to both technological and probiotic traits.
查看更多>>摘要：The present work aimed to explore the stability mechanism of Pickering emulsions (PEs) and high internal phase PEs (HIPPEs) to resist environmental stresses (i.e., pH and ionic strength) via altering the interfacial rheology and microstructure. The storage, centrifugal, oxidative stabilities and interfacial properties of PEs and HIPPEs stabilized by pea protein isolate-high pectin-epigallocatechin gallate (PPI-HMP-EGCG) complex were investigated. The compact and dense viscoelastic interfacial layers, appropriate gel-like elastic network structure and apparent viscosity allowed PEs and HIPPEs to have excellent long-term storage stability, the best centrifugal and oxidative stabilities at pH 3.5 and 0 mmol/L NaCl. As PEs and HIPPEs at neutral and alkaline conditions, the centrifugal and oxidative stabilities of PEs and HIPPEs reduced, which was ascribed to the insufficient number of complexes, leading to the formation of the weak interfacial layer and the decrease of apparent viscosity and viscoelasticity. As NaCl concentration increased to 1000 mmol/L, the oil droplets were not completely surrounded by the interfacial layer with weak viscoelastic response, which resulted in the reduction of centrifugal and oxidative stabilities. These findings are useful to broaden the application of antioxidant PEs and HIPPEs in the food industry under a wide range of pH and ionic strengths.
查看更多>>摘要：Foodborne pathogenic bacteria is a serious threat to food safety, endangers human health, and can cause huge economic losses. Thus, there is a vital need for development of novel anti-bacterial agents with feature of enhanced antimicrobial activity and high bio-safety, which have almost no influence on textural and flavor perspectives of foods. Polysaccharides are natural macromolecular polymers that are widespread in nature and have attracted much attention due to their significant bio-activities. Although polysaccharides have been demonstrated for their activities against foodborne pathogens, their antibacterial abilities and modes of action have not been systematically discussed. This review presented herein focuses on diverse antibacterial mechanisms of polysaccharides. Actually, their antibacterial mode of action was shown to be via damaging cellular structural and inhibiting bioenergetics metabolism. Additionally, for the higher antibacterial activity, probably also the new antibacterial mechanism of polysaccharides and the strategies should be developed. Accordingly, this review could open the door for the production and application of polysaccharides as novel antibacterial agents and green preservatives in the food field.
NSTL
Elsevier