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In this work, the rheological and textural properties, water-holding capacity (WHC), syneresis, and microstructure of a novel formulation of Kefir were studied by varying the incubation time and temperature, as well as the ratio of peanut-milk and skimmed-milk. Generally, all the experimental responses resulted to be significantly affected (p < 0.05) by all dependent variables examined. Kefir WHC was not significantly influenced (p > 0.05) by the fermentation temperature. 相似文献
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High pressure homogenization (HPH) is a non-thermal technology that has been widely studied as a partial or total substitute for thermal food processing. The present work evaluated the effect of HPH on the rheological properties of a fruit juice serum model, designed to be similar to tomato juice serum. Product viscosity decreased due to the increase in homogenization pressure, and could be modelled well using two functions (power-sigmoidal and exponential; R2 > 0.98). The serum model processed at 200 MPa showed a viscosity decrease of 20% when compared to the original. Since fruit juice rheology is defined by the interactions occurring between the dispersed phase (suspended particles) and the solution (serum), the expected fruit juice behaviour was then discussed. 相似文献
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High pressure homogenization (HPH) is a non-thermal technology that has been widely studied as a partial or total substitute for the thermal processing of food. Although microbial inactivation has been widely studied, there are only a few works in the literature reporting the physicochemical changes caused in fruit products due to HPH, especially those regarding the rheological properties. The present work evaluated the effect of HPH (up to 150 MPa) on the time-dependent and steady-state shear rheological properties of tomato juice. HPH reduced the mean particle diameter and particle size distribution (PSD), and increased its consistency and thixotropy. The rheological results were in accordance with the PSD observed. The rheological properties of the juice were evaluated by the Herschel–Bulkley and Falguera–Ibarz models (steady-state shear) and Figoni–Shoemaker and Weltman models (time-dependent). The parameters of these equations were modelled as a function of the homogenization pressure. The models obtained described the experimental values well, and contributed to future studies on product and process development. 相似文献
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Parsnip (Pastinaca sativa) suspensions, at concentrations corresponding to a dilute and concentrated regime, were subjected to pasteurization, and heat treatments that favored β-elimination reactions and pectin methyl esterase activity. The different heat treatments were combined with homogenization. Physicochemical properties such as content of insoluble/soluble material and insoluble/soluble pectin were measured together with particle and rheological properties. Pectin methyl esterase activity led to a high yield of insoluble material and insoluble pectin, whereas β-elimination led to a high yield of soluble material and solubilized pectin. Homogenization after heat treatment resulted in increased solubilization of the pectin, especially after β-elimination reactions. Parsnip suspensions subjected to pectin methyl esterase activity exhibited the highest elastic modulus most likely due to the cross-linked pectin conferring rigidity to the cell walls. The content of insoluble material and the particle properties such as size and rigidity are important factor for the rheological properties of concentrated parsnip suspensions. 相似文献
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Physical homogenization was applied to the production of a starch-lipid complex formed through a hydrophobic interaction between amylose and fatty acid molecules. In addition, vegetable oils as a source of fatty acids and wheat starch as a source of amylose molecules were used to produce the starch-lipid complex. The complex index was significantly (p < 0.05) increased through the homogenization, leading to the release of the amylose molecules from the starch granules and a high dispersibility of the fatty acids. In particular, the viscosity characteristics clearly demonstrated a dramatic improvement in the structural stability and retrogradation behavior as a result of the homogenization treatment. Vegetable oils with homogenization can be utilized to produce the starch-lipid complex as a food ingredient with an extended shelf-life and the improved rheological properties.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10068-021-00889-w. 相似文献
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The effects of single- or 2-stage ultra-high pressure homogenization (UHPH; 100 to 330 MPa) at an inlet temperature of 30°C on the cheese-making properties of bovine milk were investigated. Effects were compared with those from raw, heat-pasteurized (72°C for 15 s), and conventional homogenized-pasteurized (15 + 3 MPa, 72°C for 15 s) treatments. Rennet coagulation time, rate of curd firming, curd firmness, wet yield, and moisture content of curds were assessed. Results of particle size and distribution of milk, whey composition, and gel microstructure observed by confocal laser scanning microscopy were analyzed to understand the effect of UHPH. Single-stage UHPH at 200 and 300 MPa enhanced rennet coagulation properties. However, these properties were negatively affected by the use of the UHPH secondary stage. Increasing the pressure led to higher yields and moisture content of curds. The improvement in the cheese-making properties of milk by UHPH could be explained by changes to the protein-fat structures due to the combined effect of heat and homogenization. 相似文献
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M.F. San Martin-González 《LWT》2009,42(1):307-578
The rheological behavior of corn oil emulsions prepared by high pressure homogenization (HPH) was investigated. Coarse emulsions of corn oil (10-30 g oil/100 g emulsion) in casein dispersions containing 0.5-3.5 g micellar casein/100 g casein dispersion in an oil-free basis were homogenized at 0-300 MPa. Flow behavior under continuous increasing (0-150 s−1) or decreasing (150-0 s−1) shear rate was tested. Emulsions that showed macroscopic change in consistency were tested for viscoelasticity (G′). Homogenization of emulsions with low oil concentration (10 g/100 g) resulted in Newtonian behavior for all treatment pressures. The rheological behavior of emulsions with higher oil concentration (30 g/100 g) was dependent on casein concentration in the aqueous phase and varied from Newtonian to shear thinning. Homogenization pressures between 20 and 100 MPa induced the formation of a gel-like structure possibly through pressure-induced interactions between caseins surrounding adjacent droplets. 相似文献
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利用苯酚-硫酸法从15个不同地区藏灵菇样品中筛选出3个高产胞外多糖样品(K4、K7、K12)。通过单因素分析确定K4、K7、K12高产胞外多糖的条件为:接种量K4为9%、K7和K12为7%;发酵时间K12为12 h、K4和K7为18 h;发酵温度均为37℃;脱脂乳浓度均为11%。藏灵菇K4、K12分别与商业发酵剂搭配制备发酵乳,结果表明,K12发酵乳的凝乳时间最短(4.52 h),胞外多糖含量和活菌数分别保持在50 mg/L左右和8.20 log cfu/m L以上,且具有较高的持水力和黏度。 相似文献
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Effect of high-hydrostatic pressure and pH on the rheological properties of gum arabic 总被引:1,自引:0,他引:1
The effect on the viscoelastic behaviour, of pressure-treating hydrated gum arabic samples (800 MPa) at different pH values (2.8, 4.2 and 8.0) was investigated, using controlled stress rheometry. The treated samples were analysed for their complex (G∗), storage (G′) and loss (G″) moduli as a function of frequency, using dynamic oscillatory testing. Significant changes in the rheological properties were observed in both the pressurised gum solutions and in those previously buffered at pH 2.8. The gum, at its natural pH (4.25) and at alkaline pH (8.0), was enhanced by pressure treatment, but only for the already “good” quality gum samples. High-pressure treatment had substantial effects on the frequency-dependence of the moduli of both the pressurised and the pressurised/pH-treated solutions, with the latter being more pronounced, suggesting differing structures or changes in the overall degree of interaction of the gum systems after pressure treatment. 相似文献
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开菲尔的营养成分、保健功能及其产品研究进展 总被引:8,自引:0,他引:8
开菲尔是一种低糖、低热值,富含蛋白质、维生素的酒精发酵性乳饮料,是一种颇具开发潜力的营养型发酵乳.本文介绍了开菲尔的营养成分及其保健功能、开菲尔奶制品的发酵剂——开菲尔粒的微生物种类,并对功能性开菲尔饮品和纯培养发酵剂研究趋势进行了论述。 相似文献
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"Yor" is a traditional sausage like product widely consumed in Thailand. Its textures are usually set by steaming, in this experiment ultra-high pressure was used to modify the product. Three types of hydrocolloid; carboxymethylcellulose (CMC), locust bean gum (LBG) and xanthan gum, were added to minced ostrich meat batter at concentration of 0-1% and subjected to high pressure 600MPa, 50°C, 40min. The treated samples were analysed for storage (G') and loss (G″) moduli by dynamic oscillatory testing as well as creep compliance for control stress measurement. Their microstructures using confocal microscopy were also examined. Hydrocolloid addition caused a significant (P<0.05) decrease in both the G' and G″ moduli. However the loss tangent of all samples remained unchanged. Addition of hydrocolloids led to decreases in the gel network formation but appears to function as surfactant materials during the initial mixing stage as shown by the microstructure. Confocal microscopy suggested that the size of the fat droplets decreased with gum addition. The fat droplets were smallest on the addition of xanthan gum and increased in the order CMC, LBG and no added gum, respectively. Creep parameters of ostrich yors with four levels of xanthan gum addition (0.50%, 0.75%, 1.00% and 1.25%) showed an increase in the instantaneous compliance (J(0)), the retarded compliance (J(1)) and retardation time (λ(1)) but a decrease in the viscosity (η(0)) with increasing levels of addition. The results also suggested that the larger deformations used during creep testing might be more helpful in assessing the mechanical properties of the product than the small deformations used in oscillatory rheology. 相似文献
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试验研究了不同均质压力(0~120 MPa)对浓度4%的大米蛋白功能特性和物化特性的影响。结果表明:随着压力的增加,大米蛋白的溶解性显著增加(P0.01),且在120 MPa下达到最大,为82.09μg/mL;乳化活性指数先增大后降低,在80 MPa下达到最大,为14.82 m~2/g;乳化稳定性指数降低。在压力的作用下,大米蛋白的粒径减小;离子键变化不显著(P0.05);氢键、疏水相互作用、巯基及二硫键的含量均发生显著性变化(P0.05),表明高压均质对大米蛋白的三维结构产生一定的影响。 相似文献
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探讨了不同发酵温度下酸乳的表观黏度与剪切速率及时间之间的关系,并对酸乳持水力、胶体脱水收缩作用敏感性等流变学特性进行了研究。结果表明,不同发酵温度酸乳的黏度随剪切时间的延长而变小,并最终趋于平缓,都形成了触变环。表明是触变体系,酸乳触变环面积(37℃>40℃>43℃)与黏度具有很好的相关性。酸乳的表观黏度随剪切时间的变化曲线符合幂函数y=kx-n的变化规律。37℃发酵酸乳的持水力达到最高值,分别较40℃和43℃发酵酸乳的高出18%和8%,而胶体脱水收缩作用敏感性值最小,比40℃和43℃发酵酸乳的分别低13%和5%。表明低温发酵酸乳的黏度大,乳清析出少,稳定性好。 相似文献
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This study concerns the physicochemical and sensory analysis of stirred kefirs made at a laboratory scale, in which one‐third of the skim milk powder (SMP) was replaced by different inulins (long chain, native and oligofructose). The reference kefirs contained 12 g/100 g of SMP or whole milk powder. Rheological analysis showed that the kefirs were viscoelastic materials with thixotropic and shear‐thinning behaviour. Rheological data showed that SMP can be successfully substituted by long‐chain inulin; however, sensory evaluation indicated that substitution of SMP by any other kinds of inulin significantly decreased the consistency of kefirs while not affecting their flavour and odour. 相似文献
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Katleen J.R. Vallons Elke K. Arendt 《Innovative Food Science and Emerging Technologies》2009,10(4):449-456
Pressure-induced gelatinisation of sorghum starch was studied and compared to heat-induced gelatinisation. Starch suspensions were treated at increasing pressure (200–600 MPa) or temperature (60–95 °C) for 10 min. The degree of gelatinisation was determined using differential scanning calorimetry, changes in birefringence and damaged starch measurements. Furthermore, the pasting behaviour and structural changes during gelatinisation were investigated using rheology and microscopy. The pressure-induced as well as the temperature-induced gelatinisation curves were sigmoid-shaped. Gelatinisation occurred between 300 MPa and 600 MPa or between 62 °C and 72 °C. No significant differences were found between the rheological properties and the microstructure of the pressure-treated samples and the temperature-treated samples within the gelatinisation intervals. Granules lost their birefringence, but granular structure was maintained; however, when heated beyond the endpoint of gelatinisation, the formation of a “sponge-like” structure was observed. This change in structure at very high temperatures was reflected by a decrease in complex viscosity.
Industrial relevance
In order to apply high pressure as an alternative to temperature in the structural engineering of starch-based systems, a full understanding of the pressure-induced gelatinisation process is necessary. No rheological and ultra-structural differences were observed between pressure- and temperature-induced gelatinisation of sorghum starch. These results indicate that pressure treatment can be utilised as a replacement technology for temperature during processing of complex starch-containing products. 相似文献19.
Behic Mert 《European Food Research and Technology》2008,227(1):151-157
In this study, the working principles and the theoretical background of a new method to measure the viscoelastic properties
of dough in the fermentation process are presented. During measurements, the dough sample was placed between a stationary
bottom plate and an oscillating top plate and squeezed at random frequencies ranging from 10 to 100,000 rad/s. By measuring
the required force and velocity of oscillations, the mechanical impedance of the samples, defined as the ratio of the force
to oscillation velocity, was determined during fermentation. The measured mechanical impedance was used to calculate viscoelastic
properties such as elastic and loss moduli of the dough samples. The nondestructive quick measurements and data covering a
wide range of frequencies are some of the main advantages of the method. Furthermore, the described instrument can be easily
affixed to the commonly available texture analyzer type equipments. 相似文献