冷冻贮藏对马铃薯泥香气成分的影响

为探究马铃薯湿泥冷冻贮藏后口感、风味变化的原因,该试验利用冀张12马铃薯制备湿泥,通过电子鼻、电子舌及气相色谱-质谱联用对新鲜和-18℃冷冻30 d、4℃解冻12 h马铃薯泥的气味、滋味、香气成分进行测定比较。新鲜和冷冻贮藏马铃薯泥的气味、滋味、香气成分有一定差异,但有机硫化物、萜烯类、烃类、醇类和芳香族化合物在其中均含量丰富且挥发性大,是其香气的主要来源;冷冻贮藏过程降低了香气的浓郁度但并没有产生不良风味,在此过程中,苦味和咸味浓郁度未明显改变,有效降低了苦回味;冷冻贮藏过程损失了一部分香气成分的同时相较新鲜马铃薯泥产生较多的(10种)醇类物质。     

Controlled Alpha Amylase Process for Improved Sweet Potato Puree

A process using a commercial alpha amylase was developed for producing consistent sweet potato puree independent of age or seasonal variations in the raw roots. The process includes thermal gelatinization of the puree starch, enzyme hydrolysis of a portion of the puree, and subsequent blending of the enzyme-treated portion with the untreated portion. Alcohol insoluble solids decreased as the percentage of enzyme-treated puree in the mixture was increased. Chemical and rheological differences comparing purees made from fresh and stored roots became insignificant when the proportion of enzyme-treated puree was greater than 75%. Sensory texture differences were insignificant if the proportion was greater than 50%.     

Changes in Amino Acid Content of Acidified Sweet Potato Puree

The stability of nitrogenous substances in processed sweet potato puree was examined. Protein and nonprotein nitrogen (NPN) fractions were extracted from sweet potato puree adjusted to pH 4.2, treated with amylolytic enzymes and processed at 88°C to determine changes in amino acid concentrations over a 6-month period. Amino acid concentrations in the protein fraction were generally found to remain stable over the storage period. NPN amino acid concentration either remained stable or increased slightly with storage time. The results of this work indicate that there would be no appreciable loss of nitrogenous substances in sweet potato puree subjected to the conditions of the experiment.     

甘薯泥作为吞咽障碍食品的研究进展

质构改良食品作为吞咽障碍患者的安全食品,具有质地柔软、吞咽安全及满足患者营养需求的特点,不同国家对吞咽障碍食品的分级各不相同,大多都聚焦于食品本身的质构特性。近些年,吞咽障碍患者的饮食安全备受关注,开发吞咽障碍食品的研究逐渐增加。甘薯泥是新鲜甘薯经过一系列加工制成的泥状食品,保留了甘薯中绝大多数营养物质,具有柔软、营养成分高的特点,是适合吞咽障碍患者食用的质构改良食品的优质原料。但甘薯泥的质构特性受到多方面因素的影响,例如加工原料、加工工艺以及贮藏条件等,限制甘薯泥作为吞咽障碍食品在食品领域的应用。该文将对质构改良食品的分类、甘薯泥加工工艺及影响甘薯泥质构特性的研究进行综述,旨在为适合吞咽障碍患者食用的甘薯泥产品的研发及应用提供理论依据。     

Changes in Volatile Flavor Components of Guava Puree during Processing and Frozen Storage

The changes in volatile flavor components of guava puree during processing (85–88°C, 24 sec) and storage at 0°C, - 10°C and -20°C for up to 4 months was evaluated by Likens-Nickerson distillation and capillary GC-MS. Pasteurized guava puree showed increases in aldehydes and hydrocarbons with decrease in esters when compared with unpasteurized puree. There was only a slight decrease in alcohols and hydrocarbons of pasteurized guava puree stored at - 20°C for 4 mo. Remarkable increases in ethyl alcohol, n-hexanal, decanoic acid, dodecanoic acid and ethyl acetate in pasteurized guava puree were observed when stored at 0°C and - 10°C for 2 and 4 mo, respectively.     

不同糖醇对黄心甘薯浓浆品质的影响

分别添加不同糖醇（麦芽糖醇、赤藓糖醇、木糖醇、山梨糖醇）制作低糖黄心甘薯浓浆,研究其对黄心甘薯浓浆流变特性、贮藏期色泽、β-胡萝卜素含量及消化特性的影响。结果表明,所有样品均为假塑性流体,经Power-law模型拟合,麦芽糖醇与赤藓糖醇显著降低了薯浆粘度（P＜0.05）,与空白组相比体系更均匀。经过杀菌与贮藏,糖醇能够有效减少β-胡萝卜素的损失,起到稳定色泽的作用（色差值ΔE＜4）。21 d贮藏后,麦芽糖醇组中β-胡萝卜素含量为504.66 mg/kg,相比空白组,显著提高了35.54%,使抗氧化活性（DPPH·和ABTS+·清除率）也有所提高。经体外消化后,麦芽糖醇与山梨糖醇组中β-胡萝卜素的释放均高于85%。综合考虑,麦芽糖醇为开发低糖黄心甘薯浓浆的最佳选择。     

冷冻保护剂甘油-海藻糖对反复冻融处理下冷冻芋泥品质的影响

以荔浦芋及红芽芋为原料,甘油和海藻糖作为冷冻保护剂,在前期实验优化得到最佳配方的基础上,经5次冻融循环处理,深入研究复配冷冻保护剂对冷冻芋泥析水率、低场核磁、界面接触角、色差、质构及流变特性等品质的影响。结果表明：芋泥析水时间得到延缓,冻融次数为3次时,冷冻芋泥首次析出水分,最大析水率为14.611%;芋泥中结合水比例呈现先下降后上升的迁移状态;芋泥的接触角呈先增大后减小趋势。芋泥的L* 值、a* 值和b* 值都与冻融次数呈正相关;芋泥的质构特性体现出硬度增大、弹性和内聚性逐渐减小;流变性测试结果显示为芋泥触变性与粘度不断增大、G′和G″呈现上升的趋势、芋泥恢复率由74.73%逐渐降低至24.96%。     

马铃薯全粉对冷冻熟面冻藏品质的影响

将15%马铃薯生全粉和15%马铃薯熟全粉分别与小麦粉混合制作冷冻熟面,探究其在冻藏期间质构品质、蒸煮品质的变化,并通过核磁共振仪、傅里叶红外光谱仪等,研究两种马铃薯全粉对冷冻熟面中水分结合状态、淀粉分子短程有序性、麦谷蛋白大聚体含量和微观结构的影响。结果表明,添加15%马铃薯生全粉能够延缓冷冻熟面冻藏期间质构品质和蒸煮品质的下降,抑制紧密结合水向自由水迁移以及水分的散失,降低冷冻熟面老化速率,延缓麦谷蛋白大聚体解聚,面筋网络结构连续性较好。而添加15%马铃薯熟全粉的冷冻熟面在冻藏期间,蒸煮品质下降,拉断力和拉断距离显著降低,面筋网络结构的连续性遭到严重破坏,不适宜长期冻藏。因此,添加马铃薯生全粉有利于保持冷冻熟面冻藏期间的品质,延缓冻藏品质的劣变,延长冷冻熟面货架期。     

冷冻甘薯片的护色工艺

冷冻甘薯片在贮藏过程中发生的褐变与多酚氧化酶(PPO)的活性呈正相关．实验研究了甘薯片中多酚氧化酶的性质，并采用各种护色剂抑制甘薯片在冷冻加工过程中产生的褐变．结果表明，甘薯中多酚氧化酶在70℃下很不稳定，随着恒温时间的延长，活性迅速降低；甘薯中多酚氧化酶的最适pH值分别为5．0和7．5；甘薯片的最佳护色方法为热处理结合护色剂，L-半胱氨酸是较理想的护色剂，它不仅能够很好地抑制甘薯片在冷冻过程中发生的褐变，而且对甘薯的营养成分如VC具有保护作用。     

速冻甘薯制品的生产技术

本文完整地介绍了速冻甘薯的生产技术，并对其质量控制点进行了阐述。     

冷冻调理马铃薯饼加工技术的探讨

对马铃薯的预糊化实验结果揭示,在各种加热方法中,马铃薯经蒸煮25min后的糊化效果最好.正交试验结果表明,奶粉含量和黄油含量对冷冻调理马铃薯饼的感官指标有高度显著的影响.对冷冻调理马铃薯饼的油脂的测试结果显示,未经油炸的马铃薯饼的脂肪含量为4.24%,而经过油炸后的马铃薯饼的脂肪含量为11.18%.经过一个月的冻藏后,未经油炸的冷冻调理马铃薯饼的油脂的过氧化值为1.94%,而经过油炸的冷冻调理马铃薯饼的油脂的过氧化值为7.79%.     

Dielectric Properties of Potato Puree in Microwave Frequency Range as Influenced by Concentration and Temperature

Dielectric properties of potato flour-water dispersions (slurry) were measured in the frequency range of 500–2500 MHz by the open-ended coaxial probe method using a network analyzer as a function of concentration (10–25% w/w) and temperature (20–75^oC). Both commercial and laboratory prepared samples of potato flours were used. Results indicated that the dielectric constant (ε′) decreased with temperature and frequency while increased with concentration. The loss factor (ε″) increased with frequency and concentration; however, temperature showed mixed effect. Both ε′ and ε″ data in conventionally used microwave frequencies (915 and 2450 MHz) were studied as function of concentration and temperature for two sample types using a response surface methodology and found to follow 2^nd order polynomial models. Temperature and concentration contributed significantly on dielectric spectra of potato slurry and the sample source had some effect. A change in ε′ and ε″ above 70^oC could be attributed by starch gelatinization. Penetration depth (D_p) decreased with an increase in frequency and non-systematic with temperature. Addition of salt substantially reduced D_p of potato slurry.     

Properties of Starch Obtained from Frozen and Thawed Potato Tubers

Starch separated from frozen potato tubers differed from that separated from unfrozen material in the initial pasting temperature and viscosity of 7% pastes. The starch separated from frozen and thawed potato tubers was characterized by higher temperatures of pasting than starch obtained from unfrozen potato tubers. Moreover, it showed some differences in granularity, phosphorus, calcium, sodium and potassium content as well as viscosity of 7% pastes in comparison with starch obtained from unfrozen potato tubers.     

马铃薯全粉对速冻油条品质的影响

通过对油条的色泽、含油含水率、比容、复热失水率、质构以及感官的分析测定,研究了马铃薯全粉对速冻油条品质的影响。结果表明:添加马铃薯全粉能降低速冻油条的含油率,当添加10%马铃薯全粉时,速冻油条的干基含油率比对照组降低12.44%;在色泽上,添加马铃薯全粉后,油条的黄度和红度增加,白度有所降低。质构分析结果表明,添加马铃薯全粉后,速冻油条的硬度显著(p0.05)降低,弹性显著(p0.05)升高,当添加10%马铃薯全粉时,油条的弹性值最高,感官评分也最高。     

冷冻预处理对紫色马铃薯出汁率及品质的影响

冷冻取汁技术可降低紫色马铃薯压榨出汁的难度,以提高紫色马铃薯出汁率,减少紫色马铃薯营养品质的损失为目的,研究冷冻预处理条件对紫色马铃薯出汁率及品质指标的影响,通过灰色关联度综合分析确定最佳冷冻处理参数为-10℃冷冻18 h,该处理条件下各指标含量分别为:出汁率52.89%,可溶性固形物6.40%,花青素358.38%,多酚和VC分别为1.46△OD/g和11.38 mg/100 g。     

红枣芋泥的配方优化及产品特性研究

红枣芋泥是一种以新鲜芋泥为主要成分,加入适当比例红枣泥、白砂糖、柠檬酸及食盐混合调配而成的一种健康的食品。以红枣芋泥的感官评价特性为指标,在单因素试验的基础上,通过正交试验优化红枣芋泥的配方工艺;采用顶空固相微萃取制备样品,联合气质联用测定红枣芋泥主要的挥发性物质;并初步建立了芋泥的营养评价标准。通过优化得到红枣芋泥最佳配方为红枣泥10％、白砂糖3％、柠檬酸0．07％、食盐0．2％。分析表明,红枣芋泥的风味物质中相对含量较高的依次为酮类、醛类、酯类、酸类和芳香族化合物,并且较国内市场上的泥类产品具有更好的口感和风味。     

Effect of Combining Mechanically Harvested Green and Ripe Puree and Sliced Fruit, Processing Methodology and Frozen Storage on Quality of Strawberries

Small green and ripe mechanically harvested strawberries were processed into puree and combined with 60 and 80% sliced ripe fruit to determine the effects of holding after harvest, percent green fruit in puree, processing procedure and storage on quality of frozen sliced strawberries. Green and ripe fruit puree added to the sliced strawberries resulted in higher viscosity and lower ascorbic acid, total anthocyanins and red color as compared to packs with 100% sliced ripe fruit. The mixtures of sliced ripe fruit and up to 40% puree were rated acceptable by a sensory panel. Heating the puree may be beneficial to color during long-term storage. Holding of fresh strawberries for 24 hr at 24°C after cleaning decreased the ascorbic acid, viscosity of syrup and color of the frozen pack. Storage of the frozen product decreased ascorbic acid and color.     

Thermophysical Properties of Papaya Puree

The effects of soluble solids content and temperature on thermal properties of papaya puree were studied. Density and specific heat were measured using a pycnometer and differential scanning calorimeter, respectively, while thermal conductivity was measured using a line heat source probe. Thermal diffusivity was then calculated from the experimental results of the specific heat, thermal conductivity, and density. Thermal properties of papaya puree were experimentally determined within a soluble solids content range of 10 to 25 °Brix and temperature between 40 and 80°C. The density, specific heat, thermal conductivity, and thermal diffusivity of papaya puree were found to be in the ranges of 1014.6 to 1098.9 kg/m³, 3.652 to 4.092 kJ/kg °C, 0.452 to 0.685 W/m °C, and 1.127?×?10^?7 to 1.650?×?10^?7 m²/s, respectively. Moreover, the empirical models for each property as a function of soluble solids content and temperature were obtained.     

番茄浆料的流变特性

对不同浓度的番茄浆料在30～60℃时的流变学性质进行了研究.结果显示,番茄浆料为假塑体系,屈服应力值的范围比较宽(40～140Pa).通过回归分析得到数学模型K=K0exp(Ea/RT)和K=Aexp(BC).可以分别用来描述温度和浓度对番茄浆料稠度系数的影响.利用这些方程,可以预测实际加工过程中不同温度和不同浓度条件下番茄浆料的粘度.