教学课程资源库 更多>>

关键词： Oat-based drink   Wholemeal oat   Oat bran   Physical stability   Physicochemical properties  

摘要： The popular dairy alternative oat-based drink (OBD) is made from hydrolysed oat. However, natural OBD is inherently unstable. OBD is commonly made from wholemeal oat and considered to have health benefits due to the beta-glucan content. beta-glucan is also a hydrocolloid with stabilizing potential and stored mainly in the bran. This study investigated the effect of bran substitution, to traditional wholemeal oat on the stability and physicochemical properties of OBD. In addition, the effect of the loss of the beta-glucan network at neutral and acidified pH are also assessed. Products with intact beta-glucan from bran were highly viscous and, thus, stable throughout storage at 20 degrees C for 14 days, but showed a viscous gel-like tendency that is unsuitable for thin beverage applications. The loss of the beta-glucan network made thin beverage-like products that were unstable. The instabilities observed were phase separation due to thermodynamic incompatibility (bran pH 6.4), gravity separation-based creaming (wholemeal pH 6.4 and 4.2), and electrostatic complex formation (bran pH 4.2). The complex formation highlighted the slight anionic tendency of hydrolysed beta-glucan. The use of bran fraction leads to higher protein and beta-glucan content. The physicochemical balance of the products greatly influenced the stability of the product.

关键词： Lactobacillus fermentation   phosphorus content   physicochemical properties   potato starch  

摘要： The effect of different levels of phosphorus on the process of amylolytic Lactobacillus fermentation and physicochemical properties of potato starch samples are investigated. The low-phosphorus starch (LPS), medium-phosphorus starch (MPS), and high-phosphorus starch (HPS) samples, the phosphorus contents in which are 422.7, 729.5, and 936.2 mg kg(-1), respectively, are selected for fermentation. The maximum rate of Lactobacillus fermentation is observed in HPS, and the lowest rate of fermentation is recorded for MPS. The effect of phosphorus content on fermentation rate shows a different tendency from enzymatic hydrolysis. The process of fermentation exerted significant effects on the thermodynamic properties of MPS and HPS (p < 0.05). Fermentation is also found to exert significant effects on the pasting properties (exception: pasting temperatures) of potato starch samples (p < 0.05). It also influenced the properties of adhesiveness, springiness, and resilience of HPS gels and the chewiness and gumminess of MPS gels (p < 0.05). The principal component analysis results suggested that phosphorus and fermentation significantly affect the physicochemical properties of potato starch that is used to make different staple food items.

关键词： bovine lactoferrin   zinc-lactoferrin interactions   whey proteins   metallocomplexes  

摘要： One trend of the modern world is the search for new biologically active substances based on renewable resources. Milk proteins can be a solution for such purposes as they have been known for a long time as compounds that can be used for the manufacturing of multiple food and non-food products. Thus, the goal of the work was to investigate the parameters of Znbovine lactoferrin (bLTF) interactions, which enables the synthesis of Zn-rich protein complexes. Zinc-bLTF complexes can be used as food additives or wound -healing agents. Methodology of the study included bLTF characterization by sodium dodecyl sulfate-PAGE, MALDI-TOF, and MALDI-TOF/TOF mass spectrometry as well Zn-bLTF interactions by attenuated total reflection-Fourier-transform infrared, Raman spectroscopy, scanning and transmission microscopy, and zeta potential measurements. The obtained results revealed that the factors that affect Zn-bLTF interactions most significantly were found to be pH and ionic strength of the solution and, in particular, the concentration of Zn2+. These findings imply that these factors should be considered when aiming at the synthesis of Zn-bLTF metallocomplexes.

关键词： fermented goat milk   proteolysis   viscosity   gastrointestinal conditions  

摘要： We evaluated the performance of Limosilactobacillus mucosae CNPC007 as an autochthonous adjunct cul-ture in the production of goat milk Greek-style yogurt. The techno-functional, physicochemical, and sensory characteristics of the control yogurt (containing only starter culture, CY) and the probiotic yogurt (with the probiotic strain added, PY) were assessed during 28 d of refrigerated storage. Furthermore, we determined the survival of the strain throughout the gastrointestinal tract under simulated conditions. The PY yogurt had a lower extent of proteolysis index and a higher depth of proteolysis index. These results indicate that the proteolytic enzymes of L. mucosae may have a possible action in PY. The PY formulation exhibited viscosity almost 1.5 times as high as CY over the refrigeration period, probably due to higher production of exopoly-saccharides by the probiotic strain, which directly in-terferes with the microstructure, texture, and viscosity of the product. The PY formulation received higher scores for color, flavor, and global acceptance at 1 d of storage and higher texture scores at 28 d. The counts of L. mucosae remained high (>7 log cfu/g and >8.5 log cfu/g) throughout mouth-ileum digestion and storage, respectively, in PY. The autochthonous adjunct culture of L. mucosae CNPC007 can be used for production of a novel potentially probiotic goat yogurt without negatively affecting the general characteristics of the product quality, adding value associated with maintain-ing its functional potential.

关键词： Digital storage  

摘要： This study investigated the impact of sugar reduction on the physicochemical properties (pH, water activity (a(w)), total soluble solids (TSS), viscosity, and color) and microbial safety (total mesophilic and psychrotrophic bacteria, yeast and mold, total coliform, Escherichia coli, and Listeria monocytogenes) of chocolate-flavored milk stored under refrigeration (4 +/- 1 degrees C) for 28 days. When compared with the full-sugar chocolate milk (control), the 50% reduced-sugar (w/v) formulation containing concentration of stevia (56.27 mg/L) and monk fruit extract (81.90 mg/L), optimized based on the sensory responses by 107 consumers, showed no significant changes in pH, a(w), and microbial growth. However, TSS and viscosity were significantly lower with higher lightness and yellowness but lower redness values in the reduced-sugar sample compared to the control, but no significant changes were observed over the storage period. Consequently, 50% of added sugar (w/v) could be reduced to formulate chocolate milk with acceptable physicochemical properties and microbial safety. Practical applications Flavored milk is a source of recommended dietary allowances for vitamin D and calcium but can contain up to 10% of added sugar (w/v). However, the intake of high levels of added sugar has been associated with several chronic diseases. Hence, there is a need to reduce added sugar. But the impact of sugar reduction has mainly been investigated from a health perspective. There is limited data available on how this impacts physicochemical and microbial properties. These aspects are crucial to be assessed before the new product could be launched in the market. Hence, the findings from this study will provide insights to the dairy industry on the stability of a new product in terms of physicochemical and microbiological safety when considering sugar reformulation programs.

关键词： Physicochemical properties  

摘要： In view of the nutritional and sensory aspects of thyme (Thymus vulgaris), it can be added as a functional ingredient to extend the shelf life of food products. Thyme leaves powder (TLP) at different concentrations (1%, 3%, 5%, and 7%) with wheat flour in cookies formulation was added. Physicochemical composition and sensory attributes of cookies at storage intervals of 0, 15, 30, and 45 days were studied. All the properties of cookies affected significantly. During storage, TLP had a nonsignificant effect on chemical composition of cookies except moisture. There was no significant change for physical properties of cookies but fracturability, hardness, and water activity showed changes during storage. Color of cookies (L*, a*, and b*) varied from 57.79 to 42.64, 12.82 to 3.37, and 23.29 to 17.82, respectively, but storage did not affect the color. Cookies with 3% TLP were most preferred with respect to organoleptic characteristics by judges. Practical applications The present study can not only endorse the nutritional characteristics and sensory evaluation of thyme leaves powder cookies but also guide the overall community concerning the significance of thyme herb. In future, research on application of thyme in various food industries with its more striking benefits regarding safety and quality is required.

关键词： Starches   Flours   Physicochemical properties   Roots and tubers  

摘要： Underutilized roots and tuber crops have the potential to commercialize and contribute to the regular diet of the consumers. These crops provide several nutrients and health benefits, besides, to serve as major sources of carbohydrates. This study was aimed to characterize the flours and starches of Dioscorea alata (Kahata-ala-KA and Hingurala-H), Dioscorea esculenta (Java-ala-JA), Lasia spinosa and Nelumbo nucifera concerning compositional, functional and morphological parameters. The composition of carbohydrates, starch granular morphology and functional properties of selected roots and tubers were analyzed. The total dietary fiber and resistant starch contents were in the range of 6.83 +/- 0.66-39.42 +/- 0.74% and 4.65 +/- 0.56-9.54 +/- 0.71 respectively on a dry weight basis. The shapes of starch granules of D. alata, D. esculenta, L. spinosa and N. nucifera were spherical, polygonal, elongated and round to elongate respectively. There were considerable variations in total starch, total dietary fiber, resistant starch, amylose and amylopectin, water holding capacity, oil holding capacity, swelling power, water solubility and gelatinization parameters among five varieties. All tested varieties showed a considerable amount of dietary fiber and resistant starch contents that could lead to health benefits along with preferable functional properties that favorable for food product formulation.

关键词： Extrusion  

摘要： The utilization rate of oat bran was improved and wastage of resources was reduced using the micro-pulverization technology combined with extrusion in processing oat bran. The effects of micro-pulverization and extrusion treatment on the structure, color, physical and chemical properties, functional properties, and pasting properties of oat bran were evaluated via Fourier transform infrared spectroscopy, scanning electron microscopy, colorimeter, and rapid viscosity analyzer. Results showed that the pulverization and extrusion did not produce new functional groups in the bran. However, both treatment methods could increase the content of soluble dietary fiber and degree of starch gelatinization, reduce oil-holding capacity, and increase water solubility index. Micro-pulverization increased the brightness and slowly digestible starch of the bran, reduced rapidly digestible starch (RDS), and enhanced the antioxidant capacity of oat bran. Conversely, extrusion reduced the brightness and antioxidant capacity of oat bran, increased RDS. And extrusion made the surface of the bran relatively flat and denatured the protein. This study provides a theoretical basis that enterprises involved in oat processing can refer to. According to different market needs, adopt appropriate processing methods to process oat bran in order to gain more oat bran products. Novelty impact statement Micro-pulverization and extrusion had a great influence on the physical and chemical properties of oat bran. Some indicators (such as anti-oxidation, color) had completely opposite results with two treatments. micro-pulverization did not change the functional groups of bran, did not affect its beta-glucan content, but reduced its IDF content.

关键词： Dough rheology   Bread texture analysis   Starch retrogradation   Bread staling   FTIR analysis   Sensory evaluation  

摘要： Wheat flour was substituted by flour from roasted chickpeas at 10-20% (flour basis) and a multi-instrumental analytical approach was employed to explore the dough rheological behavior of the composite starch-proteins hydrated networks, the quality attributes of the resultant breads, as well as the staling process. Fortifications with roasted chickpea flour at 15 and 20% level significantly increased dough viscosity and elasticity as showed by oscillatory and creep-recovery rheological tests, implying higher dough resistance to flow and deformation that resulted in breads with significantly lower specific volumes and harder crumb than the control (bread without chickpea flour). Moreover, at 20% substitution level, the staling kinetics of composite breads, as monitored by texture profile analysis, indicated a greater extent of crumb hardening at the end of storage, whereas the level of retrograded amylopectin in the crumb as assessed by calorimetry (DSC) did not differ among samples. Nevertheless, for bread with 20% chickpea flour, FTIR spectroscopy revealed a large increase in protein beta-sheets and a further increment of such conformational change in the stored crumb, suggesting dehydration of gluten and its involvement in the staling process. Instead, formulations with 10% roasted chickpea flour did not exhibit any major influence on dough rheological behavior, as well as on textural attributes and bread staling. Furthermore, at 10% substitution of wheat flour by roasted chickpea flour, there was complete masking of the "grass-like" and reduced "beany" and "earthy" off-flavor notes in breads, as assessed by a trained panel, pointing to a product with high overall acceptability.

关键词： Microalgae   Extraction   Techno-functional properties   Emulsifying properties   Rheological behaviour  

摘要： Microalgae are a promising and sustainable ingredient for functional food development, due to their rich nutritional and health-promoting effects. Moreover, microalgae generally contain large amounts of structural biopolymers such as proteins and polysaccharides, which might display interesting technological features and rheological properties. This study aims at unravelling Phaeodactylum tricornutum extracts (PTE) potential role as structuring agents for food applications. Distilled water and a mixture of water/ethanol (75/25, v v(-1)) were used as solvents. Extracts' physicochemical properties were analysed regarding protein folding, molecular weight distribution, polymer interactions, and their main functional groups. PTE thermal properties, rheological behaviour, and emulsifying capacities were also evaluated. PTE showed different gelling mechanisms, with 40 degrees C aqueous purified extracts reporting the strongest gel character. Moreover, 80 degrees C ethanolic purified extracts showed the greatest emulsifying potential, with an initial emulsification index (EI) of around 90%. This EI decreased to 60% after 10 days, but remained constant for the following 15 days, showing an interesting emulsion stability. Overall, these findings suggest that PTE have a great potential for further application as thickening or emulsifier food ingredients. This diatom revealed to be a valuable source of structurally diverse, technologically active compounds.