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关键词： Highland barley   Germination   Extrusion   In vitro digestion   Prebiotics  

摘要： This study determined the effects of four thermal processing methods for germinated highland barley (GHB) on its nutritional composition, physicochemical properties, in vitro starch and protein digestibility, and in vitro prebiotic effects. The contents of total dietary fiber (TDF) and total phenols were significantly increased by steaming, microwave, baking and extrusion processing, while the contents of ash, starch and resistant starch were decreased. Except for baking, the other three methods improved the water hydration properties by increasing the water absorption index, water solubility index and swelling power. Thermally processed samples, especially those extruded, exhibited better thermal stability, pasting properties and in vitro protein digestibility, possibly because of the damage to the whole grain powder particles. The thermally processed digesta of GHB promoted the proliferation of Lactobacillus plantarum and L. delbrueckii in a dose-dependent manner, especially for those extruded, followed by those processed by steaming, microwave and baking. A Pearson correlation analysis showed that the prebiotic effect was positively correlated with the content of TDF in the different samples. Overall, thermal processing increased the quality and digestibility of GHB, with extrusion being the most suitable for industrial processing.

关键词： lactation   goat milk   whey protein   casein   properties  

摘要： During lactation, goat milk contains colostrum, transitional milk, mature milk, and end milk. The protein present in goat milk during different lactation periods has different characteristics. This study aimed to characterize the protein profile of goat milk samples obtained at different lactation stages and to identify changes in the physicochemical and functional properties of whey protein and casein from goat milk collected at 1, 3, 15, 100, and 200 d after calving. The results demonstrated that the lactation period had a great influence on the physicochemical and functional properties of goat milk whey protein and casein, especially the protein properties of colostrum on the first day after delivery. The denaturation temperature, hydrophobicity, and turbidity of whey protein were significantly higher on the first day postpartum than at other lactation periods. Correspondingly, the colostrum whey protein also had better functional properties, such as emulsification, oil holding capacity, and foaming properties on the first day postpartum than at other lactation periods. For casein, the turbidity, particle size, water holding capacity, and foaming properties on the first day after delivery were significantly higher than those at other lactation periods, whereas the denaturation temperature, oil holding capacity, and emulsification followed the opposite trend. For both whey protein and casein, the 2 indicators of emulsifying properties, namely, emulsifying activity index and the emulsion stability, also followed an opposite trend relative to lactation stage, whereas the changes in foaming capacity with the lactation period were completely consistent with the change of foaming stability. These findings could provide useful information for the use of goat milk whey protein and casein obtained during different lactation stages in the dairy industry.

关键词： Microalgae   Cyanobacteria   Polysaccharide   Cryptic oligosaccharide   Antioxidant   Geroprotection  

摘要： Nostoc sphaeroides is a cyanobacterium traditionally used as food and medicine in the form of macrocolonies, the main supporting matrix of which is polysaccharides. Despite recent success in industrial-scale culture of colonial N. sphaeroides, biochemical and biofunctional information on the polysaccharides during colony production is lacking. Using a size-based colony growth profiling strategy, we show here that the high/low molecular weight ratio of the polysaccharides is significantly decreased while their Fourier-transform infrared absorptions remain unchanged. Importantly, monosaccharide compositions of all polysaccharides are similar to that of field colonies, indicating a comparable quality of the cultured colony products in terms of sugar composition. Subsequent experiments using free radical scavenging and Caenorhabditis elegans survival assays demonstrate both in vitro and in vivo antioxidant activities of the polysaccharides. Furthermore, the oligosaccharides prepared by partial acid hydrolysis are, like the polysaccharides, confirmed to increase oxidative survival and lifespan of C. elegans. The oligosaccharides, but not the polysaccharides, are further shown to ameliorate polyglutamine-mediated neurotoxicity and behavioral decline in a C. elegans model of proteotoxic stress, revealing their neuroprotective activity not shown by the polysaccharides. Consistently, several stress and proteostasis-associated genes are also found to be upregulated only by the oligosaccharides. Taken together, our results reveal distinct but also shared physicochemical and biofunctional properties of N. sphaeroides polysaccharides across colony growth stages and with derived oligosaccharides and also demonstrate the potentials of Nostoc oligosaccharides and thereby their parent polysaccharides as novel geroprotectors, including their beneficial effects on stress, lifespan, and age-related symptoms.

关键词： Lentil flour   Lentil flour fortified yogurt   Quality attributes   SEM  

摘要： This study aims to assess the quality attributes of lentil flour fortified yoghurt during cold storage (6 +/- 2 degrees C) for 21 days. Yogurt formulation was based on the addition of roasted and unroasted lentil flour at rate of 4%. Three formulations (first and the second treatments were prepared with the addition of unroasted and roasted lentil flour (ULF and RLF), respectively and third one plain yogurt) were prepared from partially skimmed cow milk and fermented with specific thermophilic bacteria of yogurt. The physicochemical (pH, titratable acidity and dry extract), microbiological quality and sensory acceptance were evaluated through the entire storage period. Lentil flours structure (roasted and unroasted) has been observed, before and after addition in the yogurt, by scanning electron microscope (SEM). Results showed that addition of lentil flour significantly (p < 0.05) affected the physicochemical and sensorial properties of fortified yogurts. Low syneresis value was observed in yogurt with unroasted and roasted lentil flour, respectively compared with the control. While, the microbiological analysis showed that the yogurts are of satisfactory quality. The most preferred yogurt was the one incorporated with unroasted lentil flour. The SEM observations of lentil flours before and after addition in yogurt found the significant changes in their morphology structure.

关键词： Dehydration  

摘要： Alternative pretreatments to food materials are necessary to enhance the dehydration process and improve the quality of products. The aim of this study was to evaluate the effect of the ultrasound pretreatments on the dehydration behavior and quality characteristics of dehydrated shrimp. Shrimps were ultrasonicated in a salt solution (10%) at 4 degrees C for 15 and 30 min in an ultrasonic bath (130 W, 40 kHz) and then dehydrated and their kinetics modeled. The ultrasound pretreatments for 15 and 20 min diminished the dehydration time by 15.6% and 12.1%, respectively, in comparison with the control treatments, being the Page model the one that best described the dehydration kinetics. The content of ash significantly increased (p < .05) and the water activity (a(w)) significantly decreased (p < .05), while some rehydration quality indices also raised in the dehydrated shrimps pretreated with ultrasound in comparison with controls. Ultrasound can potentially be applied for shrimp dehydration, given the advantages in reducing processing time and improving product quality. Practical applications Shrimp (Litopenaeus vannamei) is a nutritious seafood that is appreciated for its delicious meat, which represents 53% of the world's aquaculture production of crustaceans. Unfortunately, shrimp like many foods is highly perishable;hence, different processing technologies must be applied to improve its useful life. At present, drying is the main applied method in the aquatic product processing industry, but depending of the applied conditions, changes may occur that affect the quality of the product. Pretreatments such as the ultrasound improved the dehydration process and the quality of the dehydrated shrimp. Therefore, such conditions could be used to produce ready-to-eat food from shrimp, as is currently demanded by consumers.

关键词： Dextran   gel   Maillard reaction conjugates   mechanical properties   secondary structure   sweet potato protein  

摘要： Covalently linked sweet potato protein (SPP)-dextran conjugates were produced through Maillard reaction, and the effects of this conjugation on physicochemical and gelling properties of SPP were studied. Formation of SPP-dextran-conjugated product was confirmed with increase in browning intensity and molecular weight, with concomitant reduction in free amino group content of the protein. Dry-heating period of 0, 1, 3, 5 and 7 days gave rise to 0%, 12.8%, 19.0%, 25.2% and 22.8% degree of conjugation (DC), respectively. High molecular weight protein polymer with polydispersed band above 50 kDa was formed. FTIR spectroscopic analysis showed that the C-O (amide I) and C-N (amide II) stretching bands were modified by the Maillard reaction. Conjugation of SPP with dextran reduced its denaturation temperature. SPP-dextran conjugate gels' network structures were sustained by both physical interactions and covalent bonds. SPP-dextran conjugates' gels had significantly improved hardness and resilience in comparison with the unmodified SPP (P< 0.05).

关键词： Portable X-ray fluorescence   Soil enzymes prediction   Relief   Soil quality   Prediction models  

摘要： Soil enzymes act in biogeochemical cycles of elements and are indicators of soil quality since they rapidly reflect changes of the environmental conditions. Moreover, enzymes are related to soil physicochemical properties, but their spatial distribution has been rarely evaluated. The hypothesis of this work is that soil properties related to fertility and texture (F), total contents of chemical elements obtained by portable X-ray fluorescence (pX) spectrometry and terrain attributes (T) can be used as predictor variables to soil enzyme activity, along with phytophysiognomy and season information. The objective of this work was to predict soil enzymes activity and assess its spatial variability in the most common phytophysiognomies of the Quadrilatero Ferrifero mineral province, in Brazil. Soil samples were collected in four phytophysiognomies during both dry and humid seasons. Activity of beta-glucosidase, acid phosphatase, alkaline phosphatase, urease, and hydrolysis of fluorescein diacetate (FDA) was determined. Phytophysiognomy, season, F, T, and pX, were used together or separately to predict the enzymes activity through conditional random forest algorithm and the accuracy was assessed via leave-one-out cross validation. The generated models were accurate, with coefficient of determination (R-2) varying from 0.63 (FDA by pX) to 0.82 (beta-glucosidase by F). F variables were more important for the predictions, while pX variables were more important for predicting acid phosphatase and urease. The accurate models using T variables allowed the generation of maps showing the enzymes variability along the phytophysiognomies. This approach can accelerate the determination of soil enzymes activity across the landscape.

关键词： gliadin   quercetin   NaCl concentrations   structure   physicochemical properties  

摘要： BACKGROUND Polyphenols may interact with protein via covalent bonds and non-covalent interactions, improving the structures and functional properties of the protein. The cross-linking between the polyphenol and protein is susceptible to salt (sodium chloride, NaCl) concentrations. Our study investigated the combined effects of quercetin (Q) and NaCl concentrations on wheat gliadin (G) structure and physicochemical properties. RESULTS Q and NaCl addition resulted in a more compact protein microstructure. The improved foaming and emulsifying properties indicated that the modified G might be potent as a novel surface-active agent. Differential scanning calorimetry analysis indicated that Q protected the thermal stability from destruction at 50 and 200 mmol L-1 NaCl concentrations, with narrower protein denaturation peaks. Fourier transform infrared and the Raman spectral analyses showed the secondary structural and microenvironmental changes of G. NaCl addition imparted a rearrangement of hydrogen bonds in the polypeptide chain and the disorder of protein structure, whereas Q enhanced the transition from beta-sheets and random coils to alpha-helices and beta-turns, forming a more ordered structure. Moreover, the interaction between G and Q resulted in significant disulfide bridges conformational rearrangements in the protein. CONCLUSION The results showed the benefits of natural food additives in food processing, which might have potential in improving the structure and physicochemical properties of protein-based foods. (c) 2020 Society of Chemical Industry

关键词： neutralization of ammonia   platinum   selective oxidation   XPS   supported catalysts   TEM  

摘要： Platinum catalysts prepared by incipient wetness impregnation of different supports (TiO2, WO3/TiO2, CeO2, Al2O3, zeolite ZSM-5) are tested in the ammonia oxidation reaction (TPR-NH3+O-2) and characterized by a combination of physicochemical (powder XRD, TEM, XPS) and kinetic (TPR-H-2, TPD-NH3) techniques. On the surface of all catalysts, platinum is present in the highly dispersed form (average particle size <1.5 nm), providing the activity for ammonia oxidation above 150 degrees C. In the temperature range 150-250 degrees C, the main oxidation products are nitrous oxide and molecular nitrogen whereas NOx oxides start to form at T > 250 degrees C. The highest catalytic activity is observed when platinum is supported on TiO2 promoted with tungsten. The introduction of tungsten modifies the acidity of the surface and affects the redox properties of platinum catalysts. The role of the support is found to be the stabilization of oxidized or reduced platinum forms on the surface, thus determining the total activity in the ammonia oxidation reaction.

关键词： Extrusion   Micronutrients   Oxidation stability   Potato   Red palm oil   Sweet potato  

摘要： Extruded potato (P) and sweet potato (SP) products with red palm oil (RPO) were prepared under different conditions. Superior product characteristics such as sensory score, expansion ratio, and water solubility index, among others, were obtained at high extrusion temperature (150-155 degrees C) and low water feed rate to the extruder (50.4-50.8 mL/min). The optimal products, P-1 and SP1, had high micronutrients as their total contents of beta-carotene, squalene, tocopherols, and tocotrienols were 883.2, 304.4, 262.4, and 397.0 mg/kg of oil, respectively. The average peroxide value was 4.3 meq O-2/kg oil, p-anisidine value 3.3, and induction period (100 degrees C) 11.4 h. Moreover, RPO extruded with P showed a better extrusion behavior but lower micronutrient retention and oxidative stability than that extruded with SP. Thus, the finding herein is important for investigating extrusion conditions, increasing variety, improving nutritional quality, assessing applicability and predicting the shelf-life of RPO-P/SP-extruded food.