Process optimization,texture and microstructure of novel kelp tofu

Laminaria japonica Aresch as an edible and medicine dual-purpose marine algae,has been gradually accepted by people.Tofu was Chinese traditional food,combining kelp function ingredients with tofu has practical value.The extraction-optimization methodology and the sequences of kelp antihypertensive peptide(KAP)were investigated.The sensory,whiteness,water retention ability(WRA)and microstructure of KAP tofu were evaluated.The scanning electron microscope(SEM)results showed KAP addition(20%)significantly improved the tofu texture,with a denser network composed of relatively even pores.Compared with gypsum tofu and glucose-δ-interior fat(GDL)tofu,KAP tofu had significantly higher WRA(94.49±0.49)%and sensory evaluation score value(92.54±0.52),and a significantly lower IC_(50) value at(2.06±0.04)mg/mL(P<0.05).The maximum IC_(50) value(4.14 mg/mL)of kelp enzymatic hydrolysate was observed at enzyme(at an alkaline protease:trypsin ratio of 2:1)concentration 1.5%,temperature 55℃ and time 2 h.The sequences of 8 identified peptides were Lys-Tyr,Phe-Tyr,Gly-Lys-Tyr,Ala-Lys-Tyr,Ser-Lys-Thr-Tyr,Lys-Lys-Phe-Tyr,Lys-Phe-Lys-Tyr and Ala-Lys-Tyr-Ser-Tyr with IC_(50) values of 5.24,4.83,7.94,7.52,20.63,15.33,10.73 and 2.42μmol/L,respectively.These results indicated the potential use of KAP tofu as a valuable resource for development of functional foods.

Effects of Blood Cell Membrane Disruption by Ultrasonic Technology on the Quality of Duck Blood Tofu

[Objective] The aim was to improve the quality of the duck blood tofu by ultrasonic technology. [Method] Ultrasonic technology was used to break the blood cell membrane. The optimal ultrasonic condition was determined by single factor de- sign, and the differences in sensory quality and nutritional value between the duck blood tofu treated with and without ultrasonication were studied. [Result] The optimal ultrasonic power was 400 W and the optimal ultrasonic time was 6 min. Under these conditions, the content of duck blood haemoglobin increased by 43.46%, the content of iron increased by 10.85%, and the breakage rate was 100%. The a＊ value of the duck blood tofu increased significantly under ultrasonic treatment. Both internal micro-structure and texture parameters proved that the ultrasonic contributed to the formation of gel structure. After treatment by artificial gastric juice and artifi- cial intestinal juice, the total amino acids in the digestive juice were 9.25% higher than that of the duck blood tofu without ultrasonic treatment. [Conclusion] The duck blood tofu under ultrasonic treatment would be beneficial to human body absorption, and the nutrition value would be higher as well.

TOFU/LV时辰化疗方案治疗进展期胃癌的临床研究

目的:观察和评价应用TOFU/LV时辰化疗方案治疗进展期胃癌的疗效及不良反应。方法:奥沙利铂(LOH-P)125mg/m2d1上午10时至下午4时静脉滴注,吡喃阿霉素(THP)35mg/m2d1上午10时后静冲,亚叶酸钙(CF)200mgd2-6在应用5-FU前静脉滴注。氟尿嘧啶(5-FU)400mg/m2d2-6晚10时至次日上午10时静脉滴注,并于氟尿嘧啶静滴前静注250mg/m2,21天为1周期,2个周期为1疗程,至少完成2个周期后评价疗效。结果:入组12例均可评价疗效,有效率(CR+PR)58.3%(7/12)SD25%(3/12),PD16.7%(2/12)。中位生存期(MST)10.5个月,中位疾病进展时间(TTP)5.2个月。主要不良反应为外周神经毒性,消化道反应,骨髓抑制。结论:应用TOFU/LV时辰化疗方案治疗进展期胃癌,可提高进展期胃癌的临床缓解率?延长生存期,改善病人的生活质量,且不良反应较常规化疗减轻。

An optimized industry processing technology of peanut tofu and the novel prediction model for suitable peanut varieties

Peanut protein is easily digested and absorbed by the human body,and peanut tofu does not contain flatulence factors and beany flour.However,at present,there is no industrial preparation process of peanut tofu,whereas the quality of tofu prepared by different peanut varieties is quite different.This study established an industrial feasible production process of peanut tofu and optimized the key process that regulates its quality.Compared with the existing method,the production time is reduced by 53.80%,therefore the daily production output is increased by 183.33%.The chemical properties of 26 peanut varieties and the quality characteristics of tofu prepared from these 26 varieties were determined.The peanut varieties were classified based on the quality characteristics of tofu using the hierarchical cluster analysis(HCA)method,out of which 7 varieties were screened out which were suitable for preparing peanut tofu.An evaluation standard was founded based on peanut tofu qualities.Six chemical trait indexes were correlated with peanut tofu qualities(P<0.05).A logistic regressive model was developed to predict suitable peanut varieties and this prediction model was verified.This study may help broaden the peanut protein utilization,and provide guidance for breeding experts to select certain varieties for product specific cultivation of peanut.

The Use of Fermented Whey as a Coagulant in Tofu Industries

Fermented whey （a by-product from tofu industry） has been used as a coagulant in tofu manufactures in Indonesia. This research aimed to study effects of fermented whey on coagulation efficiency and physicochemical characteristics of tofu, compared to other acid coagulants （acetic acid and glucono-delta-lactone （GDL）） and salt coagulants （calcium sulfate and natural gypsum）. A randomized block design with a single factor was used in this research. Fermented whey could be used as coagulant in tofu manufacturing. Physicochemical characteristics of tofu from fermented whey were not significantly difference compared to tofu from calcium salt and acid coagulants. Coagulation efficiencies （CF, TSIL TPR and TB~） of fermented whey are lower than that from calcium salt coagulants （calcium sulphate and natural gypsum）. Fermented whey showed no significant differences in tofu properties and parameters of coagulation process, compared to GDL and acetic acid.

Phytoestrogen Enriched Tofu from Soybean Meal

Isoflavone, a group of phytoestrogen, reduces postmenopausal symptoms and the risk of osteoporosis of women. Glycosidic forms of isoflavones are presented in non-fermented soyfoods such as tofu and they are less bioavailable than the aglycone isoflavones. Aglycone forms of isoflavones or more bioavailable forms can be increased by acid hydrolysis during tofu processing. The present study investigated the possibility of increasing the aglycone forms of isoflavones by acid hydrolysis. We used five types of tofu in this study: soybean tofu with hydrolysis, soybean meal tofu with hydrolysis, soybean tofu in general process, soybean meal tofu in general process, and commercial tofu. Defatted soybean meal was used as the major ingredient in the tofu which was made by using the new method—acid hydrolysis. To identify the isoflavone quantities in all five types of tofu, high performance liquid chromatography with diode array detection (HPLC-DAD) analysis was employed. The genistein ratio between hydrolyzed tofu and standard tofu was 1:1-8, and the daidzein ratio between hydrolyzed tofu and standard tofu was 1:6-12. The five types of tofu were analyzed for the crude protein and micronutrients such as calcium (Ca), magnesium (Mg), potassium (K), iron (Fe), zinc (Zn), and selenium (Se) by the modified Kjeldahl method and inductively coupled plasma emission spectroscopy (ICP-ES), respectively. The mean crude protein concentration of hydrolyzed tofu from soybean meal was 40.8%. In addition, especially the hydrolyzed soybean meal tofu showed the higher concentration of Ca (27,307 mg/kg) and K (25,553 mg/kg). By and large, soybean meal tofu with acid hydrolysis is a rich source of isoflavone aglycone compared with other types of tofu.

Contact Urticaria Syndrome from Tofu

A-52-year-old woman ate dinner after preening roses in her garden. Immediately, she developed oralaryngeal malaise and pruritic rash. Nasal obstruction and increase of cutaneous lesions were seen although she took betamethasone, 2 mg, orally. Physical examination revealed geographic wheal on trunk and extremities, and no overt mucosal lesions. History demonstrated that she had developed such reactions four times before: three of the four were seen shortly after eating soybean. Tofu was examined by prick-by-prick testing, and prick testing was performed with a petal, a piece of stem and rose leaf, positive and negative control. Positive reactions to tofu (wheal, 5 × 7 mm) and positive control (wheal 5 × 5 mm) and negative ones to others were noted. Although sensitization to soybean seemed to antedate pollen allergy on the basis of interview, oral allergy syndrome could be complicated because of various pollens-specific IgE. Since soy-bean specific IgE was class 2, such titer was not an effective predictor of clinical severity. This case should be classified into stage 3 of contact urticaria syndrome (CUS). Since CUS can be fatal, we must be careful in management for such patients.

Opting for Tofu & Planet Friendly

GREENHOUSE gas emissions are spiking - China’s 2009 carbon dioxide emissions alone increased nearly 10 percent in one year,according to a BP report released this past summer - and global cooperation on the matter is nil(no legally-binding deal was reached at the United Nations’ December Climate Change Conference in Cancun).Can swapping beef for tofu at the dinner table bring solace? It can,somewhat.In 2008,the UN recommended that people go meat-free one day a week to help rein in global warming. According to estimates produced that year by its Food and Agriculture Organization,nearly a fifth of the world’s green-

凝固剂及加工条件对豆腐凝胶形成及品质影响研究进展

豆腐的本质是一种蛋白质凝胶体,是大豆蛋白(主要是7S和11S球蛋白)在热处理下发生变性使蛋白质分子结构展开,再通过盐离子、氢离子或酶等凝固剂作用下发生聚集,形成致密均匀且具有网状结构蛋白凝胶。豆腐凝胶的形成及豆腐品质受多种因素的影响。本文从凝固剂种类(盐类、酸类和酶类凝固剂)以及加工条件(加工原料、制浆方法、豆浆体系pH、热处理条件)角度出发,阐明凝固剂及加工条件对豆腐凝胶形成以及品质的影响研究进展。以期为豆腐制品的工业化生产提供理论指导,为豆腐食品的研究开发与品质调控提供科学依据。

临期盒装豆腐腐败菌鉴定及抑菌效果评价

【目的】探究临期盒装豆腐优势腐败菌及对其抑制效果,延长盒装豆腐货架期。【方法】以临期盒装老豆腐和内酯豆腐为研究对象,分离优势腐败菌,并通过16S rDNA全序列分析法对腐败菌进行鉴定。分别添加不同质量浓度的山梨酸钾、脱氢乙酸钠、乳酸链球菌素单一组及3种防腐剂的复配组到样品中,采用加速试验,以抑菌率为指标,通过响应面法确定最佳复配防腐剂配方和质量浓度。【结果】临期盒装豆腐中的优势腐败菌为植生拉乌尔菌(Raoultella planticola)和沃纳利葡萄球菌(Staphylococcus warneri)。单一防腐剂的抑菌率随质量浓度的增加而增加,而复配防腐剂的抑菌效果更好。当山梨酸钾为0.21 g·L^(-1)、脱氢乙酸钠为0.15 g·L^(-1)、乳酸链球菌素为0.17 g·L^(-1)时,对植生拉乌尔菌的抑菌率最高,为25.48%;当山梨酸钾为0.36 g·L^(-1)、脱氢乙酸钠为0.11 g·L^(-1)、乳酸链球菌素为0.10 g·L^(-1)时,对沃纳利葡萄球菌的抑菌率最高,为32.07%;当山梨酸钾为0.29 g·L^(-1)、脱氢乙酸钠为0.03 g·L^(-1)、乳酸链球菌素为0.01 g·L^(-1)时,该复配防腐剂对2种腐败菌均有较好的抑菌效果,抑菌率分别为25.17%和32.42%;将该复配防腐剂添加到回接腐败菌的盒装豆腐中,并于37℃下进行储藏,处理后的盒装豆腐货架期相应延长2 d,经测算相当于在0~4℃下货架期延长7 d。【结论】在加速试验条件下,复配防腐剂可以有效抑制临期盒装豆腐中优势腐败菌,延长货架期。

2020—2023年山东省泰安市豆腐中重金属含量调查分析

目的:了解山东省泰安市豆腐中重金属含量,为预防控制重金属的急慢性中毒提供科学依据。方法:采用电感耦合等离子体质谱法检测2020—2023年山东省泰安市480份豆腐中6种元素含量,分析不同元素含量水平和趋势。结果:480份豆腐中均检出了一种或多种元素,但超标率相对较低,为8.54%(41/480)。不同年份、不同采样点之间各元素的超标率差异均无统计学意义(P>0.05)。不同种类豆腐之间各元素的超标率差异具有统计学意义(P<0.05),卤水豆腐和石膏豆腐超标率高于酸浆豆腐和内酯豆腐。不同元素的检出率和超标率有明显差别,铅和镉的检出率和超标率高于其他4种元素。结论:2020—2023年泰安市市售豆腐中,卤水豆腐和石膏豆腐中铅和镉的超标率较高。

响应面法优化冷冻鸡血豆腐的制备工艺

为使肉鸡副产物之一鸡血高效利用。以新鲜鸡血为主要原料,采用低场核磁不易流动水峰面积为评价标准,通过添加不同品种与浓度的抗冻改良剂对冷冻鸡血豆腐中不易流动水峰面积影响的单因素实验,再结合响应面设计优化冷冻鸡血豆腐的制备工艺。进一步以失水率、质构、色泽指标对优化的冷冻鸡血豆腐的品质进行分析,为开发冷冻鸡血豆腐产品提供科学依据。结果表明,冷冻鸡血豆腐优化制备工艺为:添加脂酰乳酸钠0.1%,海藻酸钾0.1%,木薯变性淀粉2%。在此工艺条件下,冷冻鸡血豆腐的低场核磁不易流动水峰面积为2143,与空白组和其他优化组相比不易流动水峰面积最大,故保水效果最好。优化制备的冷冻鸡血豆腐的硬度、咀嚼性、凝胶性以及亮度都显著(P<0.05)高于空白组(其中硬度是空白组的17倍,亮度的是空白组的1.13倍)。因此,冷冻鸡血豆腐的制备工艺可显著提高解冻后鸡血豆腐的品质,可促进肉鸡副产物高值化产品的开发。

基于主成分和聚类分析的安徽大豆品种与豆腐加工特性研究

以安徽省20个大豆品种为研究对象,测定大豆主要理化成分(粗蛋白、可溶性蛋白质、粗脂肪、水分等)及制备豆腐品质参数(湿基得率、含水量、保水性、硬度等),采用相关性分析、主成分分析及聚类分析方法对大豆品种进行综合品质评价。结果表明:大豆主要理化成分与豆腐加工品质存在一定的相关性。主成分分析得到4个主成分因子,其累计方差贡献率达72.783%,综合得分前三的品种为涡豆5、皖豆21551和皖宿1019。聚类分析将20种大豆分为Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ类,每类所含品种分别为7、3、1、7、1、1种。主成分分析得到的3个品种被归为第Ⅱ类,这类大豆粗蛋白含量高、豆腐湿基得率高。涡豆5、皖豆21551和皖宿1019这3个品种适宜豆腐的加工。

湿法糖基化改性大豆分离蛋白在低致敏千页豆腐中的应用

为寻求高效的糖基化改性条件和良好的应用途径,本文以葡萄糖、木糖两种单糖为糖基供体,探究反应时间、反应温度、蛋白与糖比例、蛋白浓度对大豆分离蛋白湿法糖基化反应的影响,分析大豆分离蛋白-葡萄糖复合物(SPI-葡萄糖)、大豆分离蛋白-木糖复合物(SPI-木糖)致敏性的变化,并将SPI-葡萄糖、SPI-木糖应用于低致敏千页豆腐生产。结果表明,木糖相较于葡萄糖更易与大豆分离蛋白发生糖基化反应,但也更容易有类黑素产生。在蛋白浓度为25 mg/mL时,糖基化反应程度最高,并且糖基化反应程度与反应温度、反应时间、糖添加量呈正相关。SDS-PAGE和傅里叶变换红外光谱分析结果表明糖基化改性使大豆分离蛋白和糖分子发生了共价结合,SPI的自由氨基减少。糖基化反应程度越高,SPI致敏性越低,SPI-木糖接枝物致敏性降低程度最高可达50%,以其为原料经谷氨酰胺转氨酶(TG酶)交联所制作的千页豆腐有良好的弹性和咀嚼性。

不同乳酸菌发酵黄浆水对酸浆豆腐凝胶特性及其品质的影响

目的研究不同乳酸菌发酵黄浆水对酸浆豆腐凝胶特性及其品质的影响,探究酸浆豆腐的凝固机制,提高酸浆豆腐的品质稳定性,量化生产工艺参数。方法以大豆为原料,分别以鼠李糖乳杆菌、耐高温鼠李糖乳杆菌、混合菌(乳酸链球菌乳亚种、嗜热链球菌和耐高温鼠李糖乳杆菌)发酵黄浆水制成的酸浆作为凝固剂制作豆腐,测定豆腐的凝胶强度、持水性、出品率、色差、质构特性、感官评价、流变特性、水分分布、二级结构、三级结构、表面疏水性和微观结构等指标。结果混合菌酸浆诱导的豆腐质构特性最好,具有较高的凝胶强度、持水性和储能模量,分别为579.63g、69.93%和8166.4Pa,感官评分最高。而耐高温鼠李糖乳杆菌酸浆诱导的豆腐凝胶强度和持水性比鼠李糖乳杆菌酸浆诱导的豆腐高。鼠李糖乳杆菌酸浆诱导的豆腐则硬度较低,为1481.38 gf,水分流动性较大。表面疏水性结果显示,混合菌酸浆诱导的豆腐表面疏水性较低,为268.75%,三级构象最为紧密,鼠李糖乳杆菌酸浆豆腐表面疏水性较大,为469.29%,三级构象较为松散。扫描电镜结果显示,混合菌酸浆豆腐呈致密均匀的三维网状结构,耐高温鼠李糖乳杆菌酸浆豆腐凝胶较为连续,孔隙较大,鼠李糖乳杆菌酸浆豆腐凝胶网络结构较松散。结论混合菌酸浆可使豆腐具有较好的凝胶特性和品质,为酸浆豆腐的品质提高提供了理论和技术支持。

CSTR处理低浓度豆腐废水的启动研究

为探究全混合式(CSTR)反应器处理豆腐废水的启动实验,在常温条件下对自行设计的CSTR反应器进行了相关实验。结果表明:在启动后的运行时间30 d后,进水COD为3500 mg·L^(-1),水力滞留时间为10 d,COD去除率达到了99.51%,池容产气率达到了0.46 L·L^(-1)d^(-1),甲烷的质量分数达到60.69%。所以,对CSTR高效厌氧反应器的低浓度废水启动方式是可行的,对原豆腐废料的降解方式也是可行的,为今后对CSTR高效厌氧反应器的设计应用提供了一种新型启动方式。

3个品牌毛豆腐风味成分对比研究

毛豆腐的风味决定了消费者的喜好程度。以3个品牌的毛豆腐为研究对象,对比分析了它们的非挥发性成分和挥发性成分。结果表明,采用高效液相色谱法共检测出7种有机酸,其中琥珀酸含量最高,其次是乳酸,含量范围分别为1.77~7.47 mg/mL,2.46~3.20 mg/mL;共检测出21种游离氨基酸,其中含量最高的氨基酸分别为谷氨酰胺、苏氨酸和精氨酸,在品牌A、B、C中含量分别为2566.55,1282.69,1465.81 mg/g;采用气相色谱-质谱法共检测出61种挥发性风味物质,品牌A、B、C中分别检测出41,38,33种;电子鼻分析显示,毛豆腐在气味上的差异主要体现在硫化物、芳香成分和氮氧化合物方面,能整体显著区分挥发性成分。OAV≥1的挥发性风味物质共15种。正交偏最小二乘判别分析表明,9种VIP>1的挥发性成分为主要差异性成分。结论:3个品牌毛豆腐风味物质之间存在显著性差异。

脱乙酰魔芋葡甘露聚糖对谷氨酰胺转氨酶凝固大豆分离蛋白凝胶品质特性的影响

为探究脱乙酰魔芋葡甘露聚糖(deacetylated konjac glucomannan, DKGM)对谷氨酰胺转氨酶(transglutaminase, TG酶)凝固大豆分离蛋白(soybean protein isolate, SPI)凝胶品质的影响,制备不同脱乙酰度(DK-1=21.30%,DK-2=36.28%,DK-3=62.85%,DK-4=87.88%)的魔芋葡甘露聚糖,并研究魔芋葡甘露聚糖(konjac glucomannan, KGM)和不同脱乙酰度DKGM对TG酶凝固大豆分离蛋白凝胶及手磨豆干品质影响。相比于空白组,KGM和DKGM提高了大豆分离蛋白凝胶的质构特性。酶交联反应8 h时,凝胶强度从92.03 g增至130.06 g,增强了复合凝胶的白度和持水性,同时蒸煮损失率从8.09%降到2.55%。相比于KGM,DKGM组复合凝胶及烘烤、灭菌后的手磨豆干的硬度、咀嚼性和黏着性均显著性增强。添加DKGM的复合凝胶热变性温度从41.35℃升至44.67℃。DK-3对手磨豆干盐分含量影响较大,所形成的复合凝胶表观形态较佳。扫描电镜观察到S-DK3组凝胶蛋白质复合物网络结构紧凑致密。综上,DKGM能改善大豆分离蛋白凝胶品质特性,适度脱乙酰度的DK-3效果更佳。因此,将KGM进行适度的脱乙酰改性有利于KGM在手磨豆干加工中的应用。

点浆条件对酸浆豆腐品质的影响

为探究点浆时豆乳温度、点浆后蹲脑温度和蹲脑时间对酸浆豆腐品质的影响,提高酸浆豆腐品质,本研究利用质构分析、SDS-PAGE和低场核磁等技术分析了豆腐品质、豆乳中蛋白凝固过程、大豆蛋白各亚基含量和水分分布的变化规律。结果表明,点浆时豆乳温度对豆乳沉淀中蛋白和大豆蛋白各亚基含量无显著影响,但对豆腐品质和水分分布有较大影响。当点浆时豆乳温度为75℃时,豆腐的硬度最小,而其弹性、得率、含水量、保水性、感官得分和T 21弛豫时间最大。蹲脑温度和蹲脑时间对豆腐品质、豆乳沉淀中蛋白含量和大豆蛋白各亚基含量影响显著,当蹲脑温度75℃和蹲脑时间20 min时,豆腐硬度最小为15.80 N,而弹性、得率、含水量、保水性和T 21弛豫时间最佳,分别为5.15 mm、241.3%、76.36%、65.68%、43.29 ms,且豆腐品质豆乳沉淀中蛋白含量最佳。当点浆时豆乳温度为75℃、蹲脑温度为75℃和蹲脑时间20 min时,豆腐品质和感官得分最优。

响应面法优化芋头豆腐酿馅料配方及其保鲜研究

以猪肉和芋头为主要原料制作豆腐酿。以感官评分为指标,在单因素试验的基础上通过响应面法优化豆腐酿的馅料配方,并进行保鲜试验。结果表明:豆腐酿馅料的最优配方为以猪肉和芋头总质量为基准,芋头添加量49.6%、食盐添加量1.0%、淀粉添加量1.6%、葱花添加量1%、蚝油添加量1%、生抽添加量1.5%、鸡蛋液添加量10%、香菇添加量2%。在4℃条件下冷藏,采用真空包装方式,乳酸链球菌素添加量为0.5 g/kg的豆腐酿馅料的保鲜期可达8 d。