托盘装生鲜猪肉新鲜度指示卡的制备与性能研究

以玉米淀粉/聚乙烯醇(PVA)复合薄膜为载体,溴甲酚紫为指示剂,制备一种应用于托盘包装生鲜猪肉的新鲜度指示卡。将不同浓度的溴甲酚紫乙醇溶液,分别与两组不同配比的复合薄膜溶液混合,流延制备指示卡,再与生鲜猪肉一同置于托盘包装中,在20℃条件下贮藏。贮藏期内定期测定猪肉的挥发性盐基氮(TVB-N)含量、感官品质、p H以及新鲜度指示卡的色差值(ΔE),分析指示卡的颜色变化与猪肉新鲜度的相关性,从而判断指示卡的有效性。结果表明,指示卡的颜色变化与猪肉新鲜度变化呈现出较好的同步性。在猪肉TVB-N含量超出国家标准(15 mg/100 g)之前,溴甲酚紫浓度为0.3%的指示卡B1指示效果最佳。     

猪肉新鲜度指示标签的制备及应用

基于猪肉在腐败过程中产生的挥发性含氮化合物会使包装中气体酸碱性发生变化的原理,以甲基纤维素和聚乙二醇-6000为基材,添加溴甲酚紫、溴百里酚蓝等酸碱指示剂,最终制得6 种方便、无损的新鲜度指示标签。将标签置于不同质量浓度的NH3环境中,6 种标签的颜色均发生显著变化,且随NH3质量浓度的增加而差异变化明显;将标签应用于生鲜猪肉贮存中,通过测定4 ℃条件下不同贮存时间猪肉各项腐败指标以及指示标签的颜色变化,探究其用于监测生鲜猪肉新鲜度的可行性。结果表明：初始pH值为4.24的溴甲酚紫指示标签可较好地区分出猪肉的3 个新鲜度等级;利用此标签的颜色测定数据建立偏最小二乘模型,对挥发性盐基氮含量和菌落总数进行预测的回归系数（R2）均大于0.92,通过标签颜色变化可以判断猪肉新鲜度。     

甘油与甲基纤维素对高直链玉米淀粉- 壳聚糖复合膜性能的影响

以高直链玉米淀粉(HACS)和壳聚糖(CS)为基本材料,甘油为增塑剂,甲基纤维素(MC)为增强剂制备可食性复合膜,研究高直链玉米淀粉与壳聚糖的质量比,甘油的添加量以及甲基纤维素的添加量对复合膜物理性能的影响,包括抗拉强度(TS)、断裂伸长率(E)、水蒸气透过系数(WVP)和色度。结果表明,壳聚糖添加量的增大与甘油添加量的增加都使高直链玉米淀粉- 壳聚糖复合膜的抗拉强度降低,断裂伸长率和WVP 显著增大,膜颜色变黄;甲基纤维素的添加改善了复合膜的机械性能和WVP,随着甲基纤维素添加量的增加,复合膜的抗拉强度和断裂伸长率都随之增大,WVP 逐渐降低,且对膜的颜色没有显著影响。     

魔芋葡甘聚糖-甲基纤维素可食膜的制备及其性能研究

利用魔芋葡甘聚糖和甲基纤维素制备可食膜,研究甲基纤维素添加量、甘油添加量、均质时间和干燥温度对可食膜性能的影响。首先进行单因素实验,得到了各个变量甲基纤维添加量、甘油添加量、均质时间、干燥温度对可食膜水蒸气透过系数(WVP)、断裂伸长率(E)、抗拉强度(TS)的影响。在单因素的基础上确定了各变量的范围,选择WVP和E作为响应值,进行了响应面优化实验。研究结果:在最优水平下,甘油添加量0.963%(V/V),甲基纤维素添加量0.238%(W/V),干燥温度59.6℃,均质时间8.91min,WVP可达到8.4511×10-10g/m·s·Pa;甘油添加量0.985%(V/V),均质时间7.68min,干燥温度40℃,甲基纤维素添加量0.363%(W/V),E可达到130.25%。     

可食性羧甲基纤维素膜制备及性能研究

该试验主要以羧甲基纤维素(CMC)为膜原料,研究影响膜性能的各种因素,并通过正交试验确定制备CMC可食性膜最佳工艺参数;最后通过验证试验得出制备可食性羧甲基纤维素膜最佳工艺条件为:CMC浓度为2%,甘油添加量为30%,倒膜量为11 g,烘烤温度为50℃;在此条件下制得膜综合评分为87.18分。     

可食性南瓜纸的制备及其性能研究

以南瓜为基材,海藻酸钠为增稠剂,甘油为增塑剂,制备了可食性南瓜蔬菜纸。研究了南瓜质量分数、海藻酸钠添加量和甘油添加量对南瓜纸各项性能的影响。结果表明:南瓜质量分数、海藻酸钠质量分数、甘油体积分数对南瓜纸各项性能有较显著的影响,并确定了各因素的添加范围:南瓜质量分数15%²5%,海藻酸钠质量浓度0.525%,海藻酸钠质量浓度0.5¹.5 g/L,甘油体积分数0.1%1.5 g/L,甘油体积分数0.1%⁰.2%;得出干燥的最佳工艺条件:干燥温度为60℃,干燥时间为6 h。     

棉秆皮微晶纤维素/β-环糊精气凝胶纤维的制备及吸附性能

棉秆皮微晶纤维素和β环糊精在尿素体系下低温溶解制备纺丝溶液,以湿法纺丝和冷冻干燥法制备棉秆皮微晶纤维素/β-环糊精气凝胶纤维,用以吸附染料废水中的亚甲基蓝。采用单因素方法分析确定了β-环糊精添加量,以及吸附条件对亚甲基蓝吸附量的影响。结果表明：棉秆皮微晶纤维素与β-环糊精质量比为5∶2,吸附温度20℃,吸附时间5 h, pH值=7时,制备的气凝胶纤维吸附效果好;染液质量浓度为50 mg/L时,棉秆皮微晶纤维素/β-环糊精气凝胶纤维对亚甲基蓝的吸附量最大,为56 mg/g;吸附过程符合准二级吸附动力学模型和Langmuir吸附等温线模型。扫描电镜结果说明添加β-环糊精的气凝胶纤维孔径比纯棉秆皮微晶纤维素气凝胶纤维孔径更大,形状更规则,对染料废水中亚甲基蓝的吸附效果更好。     

豆渣可食用包装纸的研制

豆渣含有大量纤维素和钙,含有少量脂肪,具有较高的营养价值。为扩大豆渣的利用途径,提高大豆的经济价值,以鲜豆渣为原料,通过研究酶添加量、提取温度、时间、p H对豆渣中可溶性膳食纤维提取的影响,确定最佳条件。结果表明,当酶添加量0.5%、反应时间100 min、反应温度48℃、p H 4.3时提取率最高,为4.56%。将制得的可溶性膳食纤维与海藻酸钠、CMC和甘油按比例混合,以膜抗拉伸强度为指标,探究可溶性膳食纤维、甘油、CMC、海藻酸钠的添加量对豆渣可食用包装纸性能的影响。由正交实验可知当可溶性膳食纤维添加量为2.0%、海藻酸钠1.5%、CMC0.5%、甘油1.5 m L时制得的膜性能最佳,抗拉强度为7.42 MPa。     

无纺布-纳米纤维素PU合成革的制备与研究

以无纺布为基材,研究了Na OH溶液在80℃对基布的处理时间、醇性聚氨酯涂布量、纳米纤维素纤维的用量对基布透湿性的影响以及水性聚氨酯膜定量、甘油用量对合成革物理、机械性能的影响。结果表明Na OH溶液在80℃下处理基布1h、纳米纤维素纤维的用量为3%、醇性聚氨酯涂布量为130g/m2时基布的透湿性能最好;当水性聚氨酯膜涂布量为100g/m2、甘油用量为15%时合成革的透湿性能最佳,此时合成革的表观密度、抗张强度、断裂伸长率、崩裂强度较接近天然皮革。通过扫描电镜对基材和合成革表面皮纹的形貌进行表征并对合成革的透湿性能等性能进行检测。     

谷物类物料湿法超细粉碎机理与实验研究

以碎米蛋白为原材料制备可食用膜,分别探讨了膜液pH值、碎米蛋白溶液浓度、甘油添加量和热反应温度对蛋白膜性能的影响.在单因素实验的基础上,利用响应面法对碎米蛋白可食用膜的制备工艺进行优化,得到最佳工艺条件为:pH11.5、碎米蛋白溶液浓度为5 g/(100ml)、甘油添加量2.09 g/(100ml)、温度87℃.该条件下,蛋白膜的抗拉强度为2.47MPa,断裂伸长率为175.68％,水蒸气透过率为4.84 g·mm/(kPa·d·m2),透光率为86.1％,溶解性为27.88％,综合评分为78.44,与模型预测值(78.63)相差0.24％.     

Time-Temperature Indicator using Phospholipid-Phospholipase System and Application to Storage of Frozen Pork

A novel time-temperature indicator (TTI) using phospholipid-phospholipase was developed to monitor quality change of frozen foods during storage. The ITI was more reliable than the lipase system and monitored quality changes of frozen pork during storage. The TTI was designed for reactions at sub-zero temperatures because the substrate emulsion would be stable at such temperatures. The TTI contained glycerol and sorbitol as anti-freeze reagents and was designed to show distinctive color changes according to pH by mixing bromothymol blue, neutral red, and methyl red. The TTI had an activation energy of 32.12 kcal/mol, suitable for many food reactions.     

Detection of bovine mastitis by bromothymol blue pH indicator test

A simple bromothymol blue indicator test was evaluated for farm diagnosis of mastitis. The test required highly absorbent blotting paper impregnated with four spots of bromothymol blue. Indicator color scores (1 to 4) for quarter foremilks increased with somatic cell count and pH, although variability within each color score was large. Sensitivity of the bromothymol blue test ranged from 51 to 56% and specificity from 89 to 90% for most reference criteria used to classify normal and abnormal milk. Predictability of a positive test ranged from 49 to 52% (false positives 51 to 48%) and predictability of a negative test from 90 to 97% (false negatives 10 to 3%) for the same criteria. Overall the bromothymol blue test incorrectly diagnosed 11 to 20% of 3772 quarters. By classifying color score 2 as negative, predictability of a positive result was 70 to 75% and sensitivity was 26 to 30%. The test can be used by dairy producers to screen herds with a relatively high incidence of mastitis or used in combination with cow cell counts to locate abnormal quarters. The bromothymol blue test was less sensitive than the California Mastitis Test but offered several practical advantages for use on farm.     

Determination of methanol in gardenia red and gardenia blue

The natural food color gardenia red is manufactured through the hydrolysis of the methyl ester of iridoid glucoside. Gardenia blue is also made from iridoid glucoside. Therefore, there is a possibility that the commercial products contain methanol. To determine methanol in gardenia red and gardenia blue, a headspace GC method with standard addition was developed. In the case of gardenia blue with the methyl ester, methanol may be formed during the analytical procedures for methanol. Thus, conditions in which methanol would not be produced in the headspace-GC method were investigated. Vials containing 1 g of the color preparation, 1 mL of water, and a standard solution were sealed. Equilibrium temperature was an important factor among the conditions for analyzing methanol in gardenia blue. Although at room temperature and 50 degrees C, the contents of methanol were equal, the content increased 1.2 times at 80 degrees C. Methanol contents determined at 50 degrees C were 8 and 9 micrograms/g in two gardenia red products and 25-34 micrograms/g in three gardenia blue products, which were below the residual limit of 50 micrograms/g set for many other natural food additives.     

高活性玉米膳食纤维的制备、性质与应用

以玉米种皮为原料,采用酶法制得高活性玉米膳食纤维（ＨＡＦＣ）,含有１２．６９％水溶性纤维,４４．８１％半纤维素,１３．０５纤维素与７．０４％木质素,膨胀力与持水力分别为６．５ｍｌ／ｇ和６２０％。详细论述了玉米膳食纤维的制备方法,化学成分、物化性质及在食品中的应用。     

Real time on-package freshness indicator for guavas packaging

A novel on-package color indicator has been fabricated based on bromophenol blue, and tests have been conducted to assess the freshness of guava (Psidium guajava L.). Bromophenol blue (BPB) was immobilized onto bacterial cellulose membrane via absorption method. The BPB/cellulose membrane as color indicator works based on pH decrease as the volatile organic compounds (e.g. acetic acid), produced gradually in the package headspace during developing of guava. Subsequently the color of the indicator will change from blue to green for over-ripe indication, which can be visible to the naked eye. The results showed that the color indicator could be used to determine the state of freshness of the guava at ambient condition (28–30 °C). The color change of the indicators reflects the pH of headspace of the guava packaging. Furthermore, it also in similar trends to the change of several parameters (soluble solids content, texture and sensory evaluation) that normally used to characterize the freshness of guava. Therefore, the indicator can be used for real time visual monitoring of freshness state of packaged guavas.     

溴麝香草酚蓝/玉米醇溶蛋白指示标签对金枪鱼新鲜度的监测

近年来,智能检测食品新鲜度的比色膜受到越来越多的关注。本实验利用静电纺丝技术研制出一种溴麝香草酚蓝（bromothymol blue,BTB）/玉米醇溶蛋白（zein,ZN）新型智能比色标签,用于金枪鱼鱼片的新鲜度监测。BTB在pH值为5～12时的明显颜色变化赋予了指示标签灵敏的pH值传感效果。通过场发射扫描电子显微镜、傅里叶变换红外光谱、X射线衍射、差示扫描量热仪对不同BTB添加量的BTB/ZN指示标签的形貌和结构进行表征。再将BTB/ZN指示标签应用于金枪鱼鱼片新鲜度的指示验证实验,对指示标签的指示效果进行验证。结果表明,BTB/ZN指示标签的微观结构良好,BTB可以很好地与ZN结合在一起,并且不破坏二者的结构;质量分数4% BTB的BTB/ZN指示标签的指示效果最佳,能灵敏地反映金枪鱼的新鲜度变化。指示标签的色度和金枪鱼鱼肉的总挥发性盐基氮含量之间存在显著相关性,这证明BTB/ZN指示标签能有效监测金枪鱼鱼片的新鲜度。     

滴定法滴定稻米油酸值的影响分析

研究了谷维素含量、指示剂种类、游离脂肪酸含量、油脂色泽对稻米油滴定酸值的影响规律。结果表明,当以酚酞为指示剂时,随着谷维素含量的增加,新鲜精炼稻米油和一级精炼大豆油的滴定酸值升高;但是当采用溴百里酚蓝为指示剂时,谷维素含量对两种油脂的滴定酸值无明显影响。游离脂肪酸含量以及油脂色泽对滴定酸值无显著影响。     

一种新的食品中亚硝酸盐含量测定方法研究

酸性条件下利用亚硝酸盐具有氧化性的特性氧化KI 生成I2,I2 和淀粉作用灵敏地生成I2- 淀粉蓝色络合物的特效反应,建立光度法测定食品中亚硝酸盐含量的新分析方法。研究表明,I2- 淀粉蓝色络合物最大吸收波长为540nm,在试液pH5、50ml 试液中加入1.0 × 10-2g/ml KI 10ml、0.3% 的淀粉4ml、反应时间6min 的最佳实验条件下,新建方法线性范围为8.0 × 10-4～7.0 × 10-6g/ml,检出限5.0 × 10-8g/ml,相对标准偏差0.7%。新方法具有选择性高、简单、准确和灵敏的优点。     

食品新鲜度指示器的研究与发展趋势

食品新鲜度与消费者的饮食安全密切相关。新鲜度指示器可检测食品腐败所产生的释放物并产生直观的颜色变化指示食品的新鲜度,成为研究热点。这些释放物包括挥发性盐基氮、二氧化碳、硫化氢等。围绕这些释放物分别开发了盐基氮指示型、二氧化碳指示型以及硫化氢指示型指示器。本文综述了上述指示器的工作原理及研究进展,并指出加强指示新鲜度对象的特异性识别,发展天然色素显色剂型指示器,发展接触式非破坏型指示器,发展电子式智能化指示器是主要的发展趋势。随着新鲜度指示器技术不断成熟,其在新鲜食品包装领域将会得到越来越广泛的应用。     

基于甲基纤维素改性聚乙烯醇指示膜的制备、表征及对南美白对虾的鲜度指示

为实现水产品鲜度可视化实时监测,本研究以甲基纤维素（methyl cellulose,MC）共混改性聚乙烯醇（polyvinyl alcohol,PVA）为成膜基材,复配溴甲酚紫甲基红制备指示膜,比较基材配比对结构、物理及检测性能的影响,并应用于南美白对虾鲜度检测。结果表明：各组分相容性强,流变学结果表明m（MC）∶m（PVA）＝3∶1时分子间作用力最强烈。MC的引入可改善PVA性能,当PVA和MC质量比为1∶3时,指示膜具有最高的抗拉强度（（65.36±4.29）MPa）、疏水性能（水接触角（57.30±0.81）°）和阻隔性能。各指示膜均能对pH值响应,且具良好颜色稳定性。将性能最优的指示膜用于南美白对虾（4 ℃）鲜度检测,4 d时指示膜由红褐色转为紫褐色,对应次级鲜度;8 d时pH值和总挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量分别达7.73±0.01和（60.90±7.00）mg/100 g,指示膜变为黑色,对应完全腐败。差异显著性分析表明指示膜颜色在不同鲜度区间具有明显差异,相关性分析表明指示膜色差值与pH值、TVB-N含量呈显著（P＜0.05）或极显著（P＜0.01）相关。鉴于伴随虾不同程度的腐败,指示膜可产生肉眼可辨的颜色变化,故可根据指示膜颜色对所保鲜虾类的鲜度等级进行划分,实现食品鲜度实时监控,具良好应用前景。