Effect of autochthonous starter cultures isolated from Siahmazgi cheese on physicochemical,microbiological and volatile compound profiles and sensorial attributes of sucuk,a Turkish dry-fermented sausage

The effect of adding autochthonous starter cultures isolated from Siahmazgi cheese, on the physicochemical parameters and microbial counts of sucuk was investigated during the ripening period. SPME–GC/MS was used in volatile compound analysis and a trained group of panelists carried out sensory analysis of the final product. After preliminary screening, three strains of Lactobacillus plantarum, which possess desirable technological properties, were used to prepare three starter cultures: LBP7, LBP10 and LBP14. The addition of LBP7 and LBP14 starter cultures had a significant effect (P < 0.05) on lightness, leading to higher L values compared to control sausages during the ripening period. Both LBP7 and LBP14 sausages showed higher counts of lactic acid bacteria, lower growth of Enterobacteriaceae and Gram-positive catalase-positive cocci and greatly lowered the pH value compared to control sausages throughout the ripening process. At the end of the ripening process, lactic acid bacteria counts were affected (P < 0.05) by the addition of starter culture since higher counts were observed in sausages prepared with LBP7 (9.14 log CFU/g) and LBP14 (8.96 log CFU/g) batches. The decrease of water activity during the ripening of sausages was not affected by the various starters. The texture profiles of all sausages were similar except for LBP10, which showed lower hardness and gumminess during ripening. Under the conditions of the study, volatile compounds were mainly from spices, and no marked differences were found among inoculated sausages. However, sensory evaluation revealed that most of the sensory attributes were scored higher for inoculated sausages than for the control ones. Therefore, LBP7 and LBP14 could be promising candidates for inclusion as starter cultures for the manufacture of sucuk.     

超细异形腈纶的结构及其理化性能

测试并分析一种新型超细旦异形腈纶纤维的表面形貌、化学成分、超分子结构、热稳定性能、回潮率和保温性能,研究氢氧化钠,浓硫酸,一般有机溶剂、双氧水和保险粉对其白度与力学性能等的影响。结果表明：该纤维截面呈哑铃型,表面致密,保持了普通腈纶的优良性能,具有稳定的热性能,且耐酸性,耐碱性较好,耐一般有机溶剂性好,耐氧化还原性好;回潮率和保温性能均优于普通腈纶纤维,纤维具有普通腈纶的特征基团,可用阳离子染料染色。     

Effects of starter cultures and nitrite levels on formation of biogenic amines in sucuk

The effects of starter cultures, starter A (Lactobacillus sakei+Staphylococcus carnosus) and starter B (Pediococcus acidilactici+Staphylococcus xylosus+Lactobacillus curvatus), nitrite levels (0, 75, and 150ppm) and ripening period on biogenic amine production were investigated in sucuk (Turkish dry-fermented sausage) production. Changes in biogenic amines, pH, water activity, moisture, non-protein nitrogen, nitrite and counts of lactic acid bacteria, Micrococcus/Staphylococcus, Enterobacteriaceae, and moulds-yeasts were determined. Ripening period had a very significant effect (P<0.01) on the all biogenic amines. Sausages produced by fermentation with starter cultures, as compared to natural fermentation (control), had lower amounts of putrescine, cadaverine and tyramine (P<0.05). Starter cultures A and B were found to have almost the same effect on the formation of biogenic amines. Use of nitrite in sucuk production affected the formation of biogenic amines except for spermidine and spermine (P<0.01). Lactic acid bacteria counts in the control group were lower than that of starter culture groups. Lactic acid bacteria, Micrococcus/Staphylococcus, and moulds-yeasts counts increased during ripening period while levels of species of Enterobacteriaceae decreased, which was also found to be under the detectable level (<100cfug(-1)), by day 3 of ripening.     

不同干燥方式对小麦麸皮膳食纤维理化性质的影响研究

研究了低温真空干燥和真空冷冻干燥对小麦膳食纤维理化性质的影响情况。实验发现经过两种方式所制备的小麦膳食纤维具有较强的持水力、膨胀力、吸附脂肪和亚硝酸盐的能力,但是除两者之间的持水力和吸附亚硝酸盐的能力无明显区别外,经过低温真空干燥制备的不溶性膳食纤维膨胀力强于经过真空冷冻干燥制备的膳食纤维膨胀力,而且小麦膳食纤维吸附饱和脂肪的能力强于吸附不饱和脂肪的能力。     

菠萝叶纤维化学脱胶过程中理化性能变化规律

采用纤维组分测定、单色荧光显微成像系统、傅里叶红外光谱(FT-IR)、X射线衍射(XRD)、拉伸性能测试等手段表征菠萝叶纤维在化学脱胶过程中组成、结构与力学性能的变化规律。结果表明:在化学脱胶过程中,菠萝叶纤维成分变化较大,纤维素含量由60.21%提高至80.09%,半纤维素含量由16.62%降低至7.68%,木质素含量由10.68%降低至1.03%,果胶含量由3.30%降低至1.13%;半纤维素和果胶在预酸、碱煮后发生了剧烈降解,大部分木质素还需漂白后方能去除;纤维细度逐渐变小,表面变得光滑,沟槽逐渐明显,分离度增加,均匀性提高;纤维素晶型保持不变,均属于Ⅰ型纤维素,但相对结晶度逐渐升高;纤维断裂强力和断裂强度虽然有所降低,但可满足后续纺纱要求。     

纤维对冰湖野米粉理化和消化特性的影响

目的 探究冰湖野米中内源纤维对冰湖野米粉的理化、功能和消化特性的影响。方法 以3种不同级的冰湖野米(长粒、中粒和短粒)和早籼米(对照)为原料, 将其研磨后过100目筛制备原米粉, 再采用焦亚硫酸钠法去除纤维制备去纤维米粉。利用扫描电镜和光学显微镜观察内源纤维对冰湖野米粉颗粒形貌的影响; 采用Brabender粘度仪测定内源纤维对冰湖野米粉的粘度特性的影响; 利用X射线衍射分析内源纤维对冰湖野米粉结晶特性的影响; 采用Englyst体外消化法评价内源纤维对冰湖野米粉消化性的影响。结果 不同颗粒长度的冰湖野米粉的形貌特征、结晶结构和粘度特性均无太大差异, 中粒冰湖野米粉慢消化淀粉含量最高, 短粒冰湖野米粉抗性淀粉含量最高。与早籼米相比, 冰湖野米粉起糊温度升高, 峰值粘度降低, 膨胀度降低, 快消化淀粉含量降低, 抗性淀粉含量升高。与原冰湖野米粉相比, 去除纤维后, 样品结晶度升高, 起糊温度降低, 峰值粘度升高, 膨胀度升高, 快消化淀粉含量升高, 抗性淀粉含量降低。结论 冰湖野米粉中内源纤维对冰湖野米粉粘度特性、结晶结构及消化性有显著的影响, 内源纤维的物理包埋以及与淀粉之间的相互作用, 会共同抑制淀粉颗粒的膨胀和糊化, 降低淀粉的消化酶解速率。     

活性碳纤维理化性能测试的几种方法

归纳了活性碳纤维理化性能测试的几种方法,包括活性碳纤维预氧化程度的测试方法、活性碳纤维碘吸附值测试法、四氯化碳蒸气吸附率测试法和采用BET容量法的比表面积测试法等,有利于工厂和科研参考与应用.     

再生竹子纤维理化性能探讨

文章探讨了再生竹子纤维的理化性能,对竹子纤维形态结构进行了微观分析;利用纤维强伸度测试仪对竹子纤维的机械性能进行了测试,利用差示扫描量热器和热重分析仪对竹子纤维的热学性能进行了研究.竹子纤维具有良好的吸湿性、染色性,以及抗菌除臭等特殊功能,是一种具有开发前景的新型纺织材料,在功能性纺织品的应用方面有着独特的优势.     

Effect of milk fat replacement by polyunsaturated fatty acids on the microbiological,rheological and sensorial properties of fermented milks

A modified milk (W3DD) where fat had been replaced by oils enriched in ω‐3 polyunsaturated fatty acids was used for the manufacture of a set‐type fermented product. In order to improve the organoleptic properties of the product, 30 g l^?1 whey protein concentrate (WPC) was added during the manufacturing process. Samples were fermented employing a commercial probiotic starter culture (ABT‐2), which contained Streptococcus thermophilus ST‐20Y, Lactobacillus acidophilus LA‐5 and Bifidobacterium lactis BB‐12. The acidification process was dependent on the WPC addition, which favoured the increase of viable counts, but fermentation was not influenced by the milk fat composition. The highest counts of the probiotic strains, L acidophilus LA‐5 (3.3 × 10⁵ cfu g^?1) and B lactis BB‐12 (5.5 × 10⁷ cfu g^?1), after 21 days of storage at 4 °C, were found in fermented products derived from W3DD supplemented with WPC. Addition of WPC also increased the firmness of the products and reduced syneresis. No apparent colour changes due to fat composition or WPC supplementation were observed in the products. Milk fat replacement by oils rich in ω‐3 polyunsaturated fatty acids had a negative influence on the product texture but did not affect the typical yoghurt flavour. These defects were overcome by the addition of 30 g l^?1 WPC, which improved the appearance, texture and general acceptability scores in the product. Copyright © 2004 Society of Chemical Industry     

莲纤维的物理性能及纺纱性能分析

采用生物加工的方法制取莲纤维,测定了莲纤维的线密度、长度、回潮率、强度、摩擦因数等基本物理性能,分析了莲纤维可纺性。分析表明：莲纤维具有较好的可纺性,其产品具有广阔的市场前景。     

羊毛再生蛋白-聚丙烯腈共聚纤维的理化性能

测试、分析并评价羊毛再生蛋白聚丙烯腈共聚纤维的部分物理化学性能,认为该纤维的断裂伸长率较大,断裂强度较低,卷曲弹性较高,吸湿回潮率高,保持了羊毛和腈纶的各自的优良性能,耐弱酸、弱碱性较好,且耐酸性较耐碱性好,耐一般有机溶剂性好,在中、低温条件下耐还原氧化性能好;纤维具有羊毛及腈纶的特征基团,可用酸性染料或阳离子染料染色。     

Effects of ionizing radiation on sensorial, chemical, and microbiological quality of frozen corn and peas

The effects of irradiation (0, 1.8, and 4.5 kGy) on the quality of frozen corn and peas were investigated during a 12month period of postirradiation storage at -18 degrees C. Irradiation of frozen corn and peas caused a reduction in ascorbic acid content of both vegetables and a loss of texture in peas but had no significant effects on instrumental color parameters (L*, a*, and b*), carotenoid and chlorophyll content, or antioxidant capacity of corn and peas. Irradiation reduced microbial loads of frozen peas and increased display life at 23 degrees C of thawed peas by preserving the green color, apparently because of slower increases in the population of acid-producing microorganisms in the irradiated samples. Overall, irradiation significantly reduced the microbial load and increased the display life of peas and had minimal detrimental effects on the quality of frozen corn and peas.     

Viscoelastic properties of orange fiber enriched yogurt as a function of fiber dose, size and thermal treatment

The effect of orange fiber addition on yogurt viscoelastic properties was studied, the following factors were evaluated: (i) fiber doses (0, 0.2, 0.4, 0.6, 0.8 and 1 g/100 ml) (ii) fiber particle size (0.417-0.7 and 0.701-0.991 mm) (iii) fiber addition prior or after pasteurization. (i) In yogurts with pasteurized fiber G′, G″ and complex viscosity increased with fiber dose, whereas in non-pasteurized fiber yogurts smaller fiber particles (<0.4 g/100 ml) rheological parameters decreased due to the disruptive effect of the fiber, and over 0.6 g/100 ml rheological parameters increased. The presence of particles alters yogurt structure but when the fiber dose is high enough the water absorption compensates the weakening effect of the fiber. (ii) G′, G″ and viscosity were higher in yogurts with large particles than in yogurts with fiber of smaller size. The higher the number of fiber particles, the higher the disrupting effect. (iii) Fiber pasteurization in the mix enhances its integration in the gel matrix.     

Characterization of the physical,microbiological, and chemical properties of sonicated raw bovine milk

Innovative processing technologies, such as ultrasonication, can change the properties of milk, allowing for the improvement or development of dairy foods. Yet taking bench-scale equipment to pilot plant scale has been challenging. Raw milk, standardized to 3% fat and warmed to inlet temperatures of 42 or 54°C, was exposed to continuous, high-intensity, low-frequency ultrasonication (16/20 kHz, 1.36 kW/pass) at flow rates of 0.15, 0.30, and 0.45 L/min that resulted in resident times within the reaction cell of 6, 3, and 2 min per pass, respectively. Multiple passes (3, 5, and 7, respectively) were required to obtain a total exposure time of 14 to 18 min. Evaluation of fat droplet sizes, enzyme coagulation properties, and microstructure of milk and milk gels, as well as determining compositional and lipid properties, were conducted to determine the potential of the ultrasound system to effectively modify milk. Laser scanning particle sizing and confocal microscopy showed that the largest droplets (2.26 ± 0.13 µm) found in raw milk were selectively reduced in size with a concomitant increase in the number of submicron droplets (0.37 ± 0.06 µm), which occurred sooner when exposed to shorter bursts of ultrasonication (0.45 L/min flow rates) and at an inlet temperature of 54°C. Ultrasound processing with milk entering at 42°C resulted in faster gelling times and firmer curds at 30 min; however, extended processing at inlet temperature of 54°C reduced curd firmness and lengthened coagulation time. This showed that ultrasonication altered protein-protein and protein-lipid interactions, thus the strength of the enzyme-set curds. Scanning electron microscopy revealed a denser curd matrix with less continuous and more irregular shaped and clustered strands, whereas transmission electron microscopy showed submicron lipid droplets embedded within the protein strands of the curd matrix. Processing at inlet temperature of 54°C with flow rates of 0.30 and 0.45 L/min also reduced the total aerobic bacterial count by more than 1 log cfu/mL, and the number of psychrophiles below the limit of detection (10 cfu/mL) for this study. Ultrasonication exposures of 14 to 18 min had minimal effect on the milk composition, fatty acid profiles, and lipid heat capacity and enthalpy. The findings show that this continuous ultrasound system, which is conducive to commercial scale-up, modifies the physical and functional properties of milk under the parameters used in this study and has potential use in dairy processing.     

不同提取方法对马铃薯膳食纤维化学组成和理化性质的影响

为明晰不同提取方法对马铃薯膳食纤维化学组成和理化性质的影响,分别采用酸解法、复合酶法、酶碱法提取马铃薯膳食纤维,比较了提取的膳食纤维化学组成、持水力、膨胀力、阳离子交换能力和胆固醇、亚硝酸根吸附能力。结果表明,复合酶法提取的膳食纤维中淀粉质量分数最低(11.70%),总膳食纤维(TDF)和可溶性膳食纤维(SDF)质量分数最高(74.72%、7.10%);酸解法提取的膳食纤维中蛋白质质量分数最低(2.77%)。酸解法、复合酶法提取的膳食纤维的持水力、膨胀力和阳离子交换能力显著高于酶碱法(P0. 05);复合酶法、酶碱法提取的膳食纤维具有较强的胆固醇、亚硝酸根吸附能力。结论:不同提取方法对马铃薯膳食纤维化学组成和理化性质影响很大。     

Study on chemical modification and dyeing properties of jute fiber

Glycidyl trimethyl ammonium chloride (Glytac) was used as a modifier for surface modification of jute fiber. Modifying effect factors such as Glytac concentration, sodium hydroxide concentration, temperature, and time were optimized as follows: Glytac concentration, 60 g/L; sodium hydroxide concentration, 20 g/L; temperature, 60°C; and treatment time, 60 min. After the Glytac treatment, the zeta potential value on the fiber surface increased over a pH range of 3.5–9.5. Compared to the raw jute fibers, the modified jute fibers could be dyed with reactive dye using a small amount of salt and alkali and had higher K/S values under the same dye concentration range of 0.5–8.0% (o.w.f.). Furthermore, the dyed Glytac-treated jute fibers had higher exhaustion, fixation, and total fixation and better washing fastness and dry rubbing fastness than those of raw jute fibers.     

The effects of concentration on electrical conductivity of orange juice concentrates during ohmic heating

Ohmic heating is an alternative heating technique, using an electrical current passing through the food product. It can be specially used in pumpable food lines as an alternative heating unit. In this study, orange juice concentrates having 0.20–0.60 mass fraction soluble solids were ohmically heated by using five different voltage gradients (20–60 V/cm). The dependence of electrical conductivity on temperature, voltage gradient and concentration were measured. The ohmic heating system performance coefficients were calculated by using the energies given to the system and taken by the orange juice samples. The mathematical model results, taking system performance coefficients into account, were compared with experimental ones. The predictions of the mathematical model were found to be very accurate.     

复合膳食纤维素的结构及物性研究

采用大豆纤维素为基料,水溶性天然植物胶——瓜尔豆胶、果胶为辅料复合后,制备一种兼有水溶性和非水溶性双重特性的复合膳食纤维素。测定复合膳食纤雏素的粘度和表面张力,并对复合膳食纤维素体系进行扫描电镜观察后发现,大豆纤维素与瓜尔豆胶复合物的粘度和表面张力较两种单一成分均有明显提高,且复合物可调和成为以瓜尔豆胶溶胶为基体、大豆纤维素颗粒均匀镶嵌其间的稳定体系。大豆纤维素与果胶复合物的上述指标也有提高,但体系不稳定。