魔芋葡甘聚糖基吸水剂的保润性能研究

以魔芋葡甘聚糖(KGM)及其衍生物魔芋超强吸水剂(KSAP)为对象,考察在烟草薄片中的保润效果,并与甘油、丙二醇进行了对比。同时采用回归方程建立KSAP在烟草薄片中的保润模型。结果表明:KGM、KSAP的保润效果优于甘油和丙二醇,且KSAP的保润效果最好。烟草薄片的水分比率(MR)与KSAP浓度(c)和保润时间(t)的相关性模型为MR=exp[(0.0036Ln(c)-0.0199)t]。     

基于不同数学模型的魔芋水分吸湿等温线模拟

根据吸附原理,采用静态调整环境湿度法,测定了魔芋在20、30、40℃3个温度下,0%~98%水活度范围内的平衡含水率,绘出魔芋的吸湿等温线。结果显示,魔芋的吸湿等温线属于II型等温线;在一定的水活度下随着温度的升高魔芋的吸附能力下降。并以平均相对误差和决定系数为评价指标,用八种数学模型对实验数据进行拟合,结果表明Peleg模型对魔芋的吸湿等温线拟合效果最好。     

魔芋超强吸水剂在奶茶粉中的抗结性能研究

测试了魔芋超强吸水剂(KSAP)和二氧化硅的吸湿和保水性能,并比较了二者在奶茶粉中不同剂量的抗结性能.结果表明:在RH=90%±3%、T=25±1℃的高湿环境中放置3个月,奶茶粉添加2.5‰的KSAP抗结性能优于添加2.5‰的二氧化硅,其流动性指数为62.5,水分活度为O.385;在奶茶粉中,KSAP比二氧化硅更具有竞争吸湿抗结的优势.     

魔芋葡甘聚糖保润剂对烟丝吸湿特性的影响

利用烟草等温吸脱附性能检测装置考察施加了魔芋葡甘聚糖(KGM)保润剂的烟丝样品的吸湿特性,结果表明:KGM有助于增强烟丝的持水能力,减缓水分散失过程,KGM不同程度地降低了各部位烟丝的干燥速率常数;烟丝样品的等温吸湿—解湿曲线呈Ⅲ型吸附曲线,且KGM的施加会加剧吸湿滞后现象,吸湿滞后行为随温度升高有减弱趋势,中上部烟丝的吸湿滞后现象强于下部烟丝,DLP经验模型可较好地描述烟丝样品的等温吸湿—解湿行为。     

魔芋葡甘聚糖及其衍生物对禽肉重组火腿物性的影响

研究魔芋葡甘聚糖(KGM)及其衍生物(KSAP)对禽肉重组火腿感官、微观结构和力学特性的影响。感官评价结果表明：与未添加改良剂的空白组和添加复合磷酸盐的对照组相比,KGM和KSAP 均能有效改善鸭肉和鹅肉重组火腿的感官指标,减少表面油脂和水分析出。通过扫描电镜观察发现：添加KGM 和KSAP 后,火腿具有均匀致密的网络结构,原料肉组织表面覆盖连续包膜层。质构分析结果表明：与空白组和对照组相比,添加KGM和KSAP 的禽肉重组火腿组织致密性增强,凝胶弹性增大;火腿硬度值、胶着性和咀嚼度降低,弹性改善。     

魔芋超强吸水剂吸湿性能研究

通过与变色硅胶和蒙脱石进行比较,研究了魔芋超强吸水剂(KSAP)在不同湿度环境下的吸湿性能,同时对它们进行了解吸性能比较,了解它们在吸湿后的保水性能。结果表明,在RH=30%±1%,T=25±1℃时,硅胶和蒙脱石的吸湿性较好;在RH=75%±1%,T=25±1℃和RH=90%±1%,T=25±1℃的环境中,硅胶和蒙脱石在1d前较KSAP高,但之后KSAP的吸湿性表现较好,9d时吸湿率分别达到70%和120%,且保水能力好。     

6种常用饲料原料平衡水分吸附等温线研究

通过研究6种常用饲料原料（小麦粉、米糠、棉粕、芝麻粕、玉米蛋白粉、DDGS）的平衡水分吸附等温线，评价了修正Halsey（MHAE）、修正 Henderson（MHE）、修正Chung-Pfost（MCPE）、修正3参数GAB（MGAB）、修正Oswin（MOE）等5种农产品常用的吸湿方程对这几种饲料原料平衡水分吸附等温线的拟合效果，发现小麦粉平衡水分吸附等温线：MGAB方程在15、35℃时拟合效果最好，MHE方程在25℃时拟合最好；米糠平衡水分吸附等温线： MOE方程在15、25、35℃时拟合效果均为最好；棉粕平衡水分吸附等温线：MOE方程在15、25℃时拟合效果最好，MGAB方程在35℃时拟合最好；芝麻粕平衡水分吸附等温线：MOE方程在15、35℃时拟合效果最好，MHAE方程在25℃时拟合最好；玉米蛋白粉平衡水分吸附等温线：MHE方程在15℃时拟合效果最好，MCPE方程在25℃时拟合最好，MOE方程在35℃时拟合最好；DDGS平衡水分吸附等温线：MGAB方程在15℃时拟合效果最好，MOE方程在25、35℃时拟合效果最好。并选择拟合最佳的方程计算出6种饲料原料的绝对安全水分和相对安全水分，以期为饲料贮藏和防霉工作提供数据指导。     

魔芋葡甘聚糖可食膜配方优化

本文以羧甲基魔芋葡甘聚糖(CMK)、魔芋葡甘聚糖(KGM)、甘油和明胶为原料制备可食膜。在单因素实验的基础上,选取CMK、KGM、明胶和甘油用量作为自变量,分别以抗拉强度TS(Y_1),断裂伸长率E(Y_2),热封强度SS(Y3)为响应值,利用响应面分析法优化原料配比,并进行验证实验。结果表明,CMK用量为1.42%,KGM用量为0.25%,明胶用量为0.33%,甘油用量为0.23%时所得复合膜的性能最好,此条件下可食膜TS、E、SS的预测值分别为10.58 MPa、20.24%、4.36 N/15 mm,验证值为(10.37±0.61)MPa、19.98%±0.92%、(4.35±0.15)N/15 mm与之接近,优化结果可靠。优化后膜的热封性得以改善,有利于其在实际中的应用。     

静电纺魔芋葡甘聚糖—纳米四氧化三铁复合膜的力学性能研究

将魔芋葡甘聚糖—纳米四氧化三铁共混,通过静电纺丝技术进一步制备多纳米纤维复合膜,研究纳米四氧化三铁、KGM、甘油、Na_2CO_3含量对复合膜力学性能的影响。结果表明,纳米Fe_3O_4、KGM、甘油、Na_2CO_3含量对复合膜性能有较大影响,当纳米Fe_3O_4含量为1.0%,KGM含量为1.2%,甘油含量为0.1%,Na_2CO_3含量为0.1%时,制得的复合膜的拉伸强度为28.35 MPa,断裂伸长率为6.42%。     

魔芋多糖及其在茶汤中的流变学特性研究

本试验研究了魔芋多糖(KGM)及其添加到茶汤中的流变学特性。结果分析表明:KGM含量≥0.100%以上时,其水溶液和魔芋茶汤的流变类型均属非牛顿型流体(n<1),且为假塑性液体。在KGM含量为0.100%、0.150%和0.200%时,其水溶液和魔芋茶汤的稠度系数K值和流动特性指数n值分别为,K值:1.189×10-2,2.778×10-2,1.583×10-1(KGM);5.851×10-3,9.75×10-3,2.824×10-2(魔芋茶汤);n值:0.9388,0.8897,0.7229(KGM);0.9584,0.9554,0.9048(魔芋茶汤)。而KGM含量小于0.100%(如0.075%、0.050%)时,则属牛顿型流体(n≈1),首次明确了KGM水溶液和魔芋茶汤的牛顿流体与非牛顿流体的临界浓度,为魔芋多糖作为饮料稳定剂奠定了理论基础。实验结果还表明,KGM含量相同的魔芋茶汤粘稠度较KGM水溶液的小,更易流动,因而更接近牛顿流体,而KGM水溶液则偏离牛顿流体。另外,在相同KGM含量下,魔芋茶汤的触变性粘度比KGM流体的小,并且很小的温度变化即可导致流体较大的粘度变化,魔芋茶汤的表观活化能只有1.0737kcal/mol。这表明KGM在稀溶液中的物理状态极易受温度影响。     

Mechanism of lowering water activity of konjac glucomannan and its derivatives

Moisture retaining materials are widely used in the food, cosmetic and tobacco industries. Conventional materials, for example, glycerin and propylene glycol have reasonable moisture absorption abilities, but poor moisture retention. Konjac glucomannan (KGM) is a heteropolysaccharide made up of glucose and mannose, linked with β-1,4 glycosidic bonds. Konjac superabsorbent polymer (KSAP) is a derivative containing hydrophilic groups and a network structure prepared by grafting sodium acrylate on to KGM. Previous work has shown that KGM and KSAP have properties which can lower water activity (a_w). The objective of this paper is to consider the mechanism of this process. Filter-paper is used as a model fiber instead of tobacco, where this effect is practically important. Moisture absorption and retention of KGM and KSAP are compared with glycerin and propylene glycol. Moisture desorption isotherms have been determined and fitted to the GAB model. The results show that the moisture retention of KGM and KSAP are better than propylene glycol and glycerol. At a given moisture content, a_w of filter-paper containing KSAP was the lowest. The monolayer moisture content and net isosteric heat of desorption of filter-paper containing KGM and KSAP were greater than that of the control groups. This study demonstrated that KGM and KSAP have the potential to be used as moisture retaining ingredients.     

不同植物多糖对烟丝吸湿性和保润性的影响及其作用机制

以常见的烟草保润剂丙二醇和水为对照,比较了黄精多糖、葫芦巴多糖、小球藻多糖和灵芝多糖的吸湿保润效果,结果表明黄精多糖具有与丙二醇类似的吸湿性,但其保润效果显著优于丙二醇。以常见薄层干燥模型对烟丝低湿条件下的解吸过程进行非线性拟合,比较干燥速率常数(k)和解吸速率,发现添加黄精多糖的烟丝,干燥速率常数最小,解吸速率最慢。低场核磁(LF-NMR)结果表明,相比于空白烟丝和添加丙二醇的烟丝,黄精多糖的添加使得烟丝中物理结合水含量下降,化学结合水含量显著增加。因此,黄精多糖可以作为一种天然高效的保润剂应用于烟草,防止烟草在贮藏过程中水分的散失。     

两种新型多羟基类保润化合物的合成及应用

以D-甘露糖（Ⅰ）为原料,成功合成了两种新型多羟基类保润产品分别是1-O-羧甲基-D-呋喃甘露糖（Ⅴ）和1-O-羟乙基-D-吡喃甘露糖（Ⅶ）,利用IR,1H-NMR和13C-NMR证实了每步产物的结构。以D-甘露糖、丙二醇、甘油和山梨醇为对照,以烟丝含水率为指标对Ⅴ和Ⅶ的物理保润性能进行评价,并以卷烟感官舒适度验证其在卷烟中的应用效果。结果表明:①目标产物Ⅴ和Ⅶ最终总产率分别是56.2%和50.6%;②Ⅴ的保湿性能优于丙二醇、甘油和山梨醇传统保润剂,Ⅶ的保湿能力略差于丙二醇,但优于甘油和山梨醇;③Ⅴ和Ⅶ具有使卷烟烟气圆润、柔和,减少刺激性和杂气,提升口感舒适性的作用。      

Moisture sorption characteristics of dried acid casein from buffalo skim milk

Adsorption and desorption isotherms of dried acid casein prepared from buffalo skim milk were determined at 25°, 35° and 45 °C over a water activity range of 0.11-0.97 using static moisture gain/loss from test samples. Both the adsorption and desorption isotherms exhibited sigmoid shape corresponding to type II, typical to many foods. There was generally a negative temperature effect on equilibrium moisture content. The effect of temperature was, however, statistically not significant over the temperature range of 25-45 °C. Of the seven sorption models tested for fitting the sorption data, the GAB model gave the best fit at all the three temperatures. The temperature dependence of GAB parameters has been determined in the form of Clausius-Clapeyron equation. The calculated values of monolayer moisture content from BET isotherm equation have been found to be lower than the corresponding values found by using GAB equation. However, in both cases the monolayer moisture was higher in desorption than the adsorption and deceased with increase in temperature. The net isosteric heat of sorption decreased exponentially with increasing moisture content and approached a constant value of 0.331 kJ/mol at moisture content 28 g/100 g (d.b.). The moisture sorption hysteresis observed at 25°, 35° and 45 C was statistically significant. The extent of hysteresis was negligible in monolayer moisture content region, occurred predominantly in the water activity range 0.35-0.60 and decreased at higher water activities. Total hysteresis energy was evaluated from the sorption data using Everett and Whitton plot. The effect of increase in temperature was to decrease the amount of hysteresis.     

Moisture Sorption Characteristics of Freeze Dried Blueberries

Moisture sorption isotherms of freeze dried lowbush blueberries at 4, 16, 25, 35, and 45°C were determined using indirect gravimetric method. Moisture sorption kinetics at these temperatures and 75% RH were also investigated. The isotherms followed a type III shape with a temperature inversion effect at 0.9 water activity. They were best described by the GAB equation. Net isosteric heat of moisture sorption in freeze dried blueberries, determined using the Clausius Clapeyron equation, varied from 5.5 to 0.25 kJ/mol as moisture content changed from 8 to 36% (dry basis). Moisture adsorption kinetics in freeze dried blueberries were well described by the first order kinetics equation. The rate constant followed the Arrhenius relationship with an activation energy of 38.6 kJ/mol.     

几种保润剂的性能比较

为提高在制品烟草的加工质量,以丙二醇和空白样品为对照,对麦芽低聚糖醇、NCS、D-吡喃半乳糖醛酸、PDSI-101和壳聚糖衍生物的保湿性能及其对烟丝的保润效果进行了实验对比,并对加料卷烟进行了感官评吸。结果表明,与丙二醇相比,5种保润剂的保湿率均有一定的提高;不同保润剂之间的保润效果存在一定的差异,其中NCS、D-吡喃半乳糖醛酸、PDSI-101和壳聚糖衍生物的保润作用较强,而麦芽低聚糖醇和丙二醇的保润效果稍差。加入保润剂3~4d,烟丝的含水率均有所回升,之后又有不同程度的下降;除壳聚糖衍生物外,其它保润剂均对卷烟的吸味无负面影响。     

Equilibrium Sorption Isotherms and Isosteric Heat of Rose Hip Fruits (Rosa Eglanteria)

For sorptional data to be useful in simulation and design purposes, they must be represented by equations valid in the conditions usually found in industrial practice. In this regard sorptional models that include the influence of temperature on desorption and sorption equilibrium values are most valuable. In this article, water desorption and sorption isotherms of rose hip fruits (Rosa Eglanteria) were experimentally determined by the gravimetric method, and from these the isosteric heat of sorption was calculated. According to the ANOVA test carried out for this fruits, no significant differences were found between experimental desorption and adsorption isotherms. Seven models were tested to mathematically represent the moisture content as a function of water activity (a_w) in the a_w range of 0.11 to 0.85 and temperatures of 20, 40, and 60°C, for further use in process simulation.

The five-parameter GAB model was most accurate, with an MRE of ?2,9 % and R²?=?0.989. The values obtained for the isosteric heat of sorption were fitted with a previous published equation, with an MRE%?=??0.05. The isosteric heat of sorption derived from the GAB five parameters equation, for the corresponding monolayer moisture content, only differed by 1.25% with the calculated in this paper.     

Water Sorption Isotherms and Crispness of Fried Yam Chips in the Temperature Range from 293K to 313K

Water sorption isotherms of fried yam chips were determined using a static gravimetric method with saturated salt solutions in the range of water activity between 0.22 and 0.85 at 293, 303 and 313K. Four sorption models namely GAB, Peleg, modified Mizrahi, and BET were fitted with the sorption data generated. The GAB model followed by Peleg and modified Mizrahi models were found to best represent the experimental data in the a_w range of 0.22–0.85. However, the BET model was more applicable between a_w range of 0.22–0.55. The adsorption isotherm of fried yam chips clearly showed the influence of temperature, decreasing the moisture content at a fixed water activity value with higher temperature. The net isosteric heats of sorption of water were estimated by applying the Clausius–clapeyron equation to the adsorption isotherms at different temperatures. The net isosteric heat of sorption was observed to be decreasing as moisture content increases. Samples stored in desiccators of 0.44 and 0.55 a_w at 303 and 313K, respectively, were rated higher in terms of textural properties investigated.     

Moisture Sorption Isotherms of Canola Meals, and Applications to Packaging

Moisture sorption isotherms were determined for defatted canola meal at 16, 22, and 34°C. The isotherms were fitted to the Guggenheim-Anderson-deBoer (GAB) sorption equation. This equation was then used to develop a packaging model that predicted the changes of moisture con-tent of canola meal under stated environmental and packaging conditions. The model was tested using Melinex 813 (12 μm) and Propafilm C (28 μm) packaging films at 86% relative humidity and 23°C. The GAB equation provided a good fit to experimental data (<3% RMS). The monolayer moisture content of the meal was 9.5%. The enthalpy of sorption of the monolayer at 22°C was 84.61 KJ/mol. The model predicted the time required by packaged canola to attain a selected moisture content ± 0.5 days.