汤汁特性对罐藏黄桃贮藏期质构品质的影响

为探究汤汁特性对罐藏黄桃质构品质的影响,本实验以‘金童5号’黄桃为材料制成黄桃罐头,研究贮藏期间汤汁特性,如pH值、可溶性固形物（total soluble solid,TSS）含量、浊度、色泽、表观黏度、渗透压及汤汁水溶性果胶（water soluble pectin in syrup,SWSP）含量的变化,并采用扫描电子显微镜和光学显微镜观察贮藏期间罐藏黄桃果肉微观结构。结果表明：同一贮藏时间、不同取样位置（上、中、下层）汤汁pH值、TSS含量无显著差异,可以认为贮藏期间汤汁与黄桃细胞组分之间的传质是均匀的;随着贮藏时间的延长,汤汁pH值未呈现显著变化,TSS含量、亮度（L*值）和红绿度（a*值）均先总体呈现下降趋势,浊度、黄蓝度（b*值）、渗透压、SWSP含量总体先呈现上升趋势,并均在贮藏后期变化趋于平缓;贮藏过程中,罐藏黄桃果肉细胞发生形变或坍塌、细胞间隙增加,宏观表现为果肉质构软化,即硬度、咀嚼性显著降低（P＜0.05）;罐藏黄桃果肉质构与汤汁特性相关性分析发现,果肉质构特性（硬度、回复性、凝聚性、咀嚼性）与b*值、浊度、渗透压、SWSP含量呈显著负相关（P＜0.05）,果肉硬度、咀嚼性与L*、a*值呈显著正相关（P＜0.05）,可以推断汤汁特性显著影响罐藏黄桃质构,可以通过调控汤汁特性改善罐藏黄桃的质构品质。     

渗透脱水循环处理对糖液及桃片理化特性的影响

以白桃片为实验材料,追踪分析了单阶段(糖液浓度不变)和多阶段(糖液浓度逐渐增加)渗透脱水循环处理后糖液特性和桃片理化特性的变化。糖液循环利用5次,期间不做任何调整。结果表明:随着糖液循环利用次数的增加,单阶段渗透脱水处理过程中糖液黏度降低、稀化现象严重,导致渗透压力差减小,使桃片水分损失率和固形物增加率逐渐降低,同时桃片中可溶性物质的溶出致使糖液电导率、浊度、色差值显著增加;多阶段渗透脱水循环处理基于多浓度糖液组合利用,有效降低了循环利用过程中糖液稀化现象的发生,保持了较好的渗透压力差,进而有利于桃片更多固形物的获得和更多水分的散失,且糖液的电导率、浊度等特性得到了较好的保持,但是多阶段渗透脱水循环处理会使桃片与空气接触更多,不利于产品色泽的保持,且长时间的高渗透压导致桃片中可滴定酸含量显著改变。从糖液循环利用中桃片渗透脱水效率和糖液特性保留角度出发,多阶段渗透处理可在桃片渗透方式的选择上提供一种新颖的思路,具有良好的应用前景。     

多维度表征渗透脱水组合干燥桃脆片的质构特性

为解析糖液渗透脱水组合干燥桃脆片质构品质的差异性,以桃为试材,采用两种渗透糖液(蔗糖和低聚异麦芽糖)对桃片进行渗透脱水预处理,之后分别组合热风干燥、真空冷冻干燥和压差闪蒸干燥制备桃脆片。多角度追踪分析不同渗透脱水组合干燥桃脆片宏观质地和微观结构方面的差异性。试验结果表明:渗透脱水预处理中糖分子渗入原料组织均能诱导原料细胞出现一定程度的坍塌和破损,同时糖分子的渗入增强了组织固化,使产品硬度增加了9.03%~158.98%。基于各干燥技术的特点分析,渗透脱水预处理使真空冷冻干燥脆片体积减小,而显著促进热风干燥和压差闪蒸干燥桃脆片皱缩度降低至0.724~0.798和0.436~0.570,同时增加脆片表面积,降低吸光性,改善产品色泽。相关性分子表明,硬度与固形物增加量(SG)呈现正相关,表明渗透脱水能够显著影响干制桃脆片的质构特性。此外,本研究所选用的质构评价指标之间均呈现一定的相关性。采用多角度进行渗透脱水组合干燥桃脆片的质构品质分析,为揭示桃脆片质构形成机制提供理论依据。     

去皮方式对黄桃渗透脱水组合干燥特性及理化品质的影响

为探究去皮方式对黄桃渗透脱水组合干燥特性及理化品质的影响,以金童8号黄桃为原料,分别采用手工去皮、碱液去皮、超声-碱液去皮和过热蒸汽去皮处理样品,测定其果肉得率。系统分析渗透脱水过程中黄桃果肉水分损失量(WL)、固形物增加量(SG)以及热泵干燥过程中水分和干燥速率变化情况,测定黄桃果干的类胡萝卜素含量、色泽、质构、微观结构和果胶溶出率。结果表明:渗透脱水组合干燥过程中,WL和SG随时间呈非线性增加的趋势,水分比和干燥速率随时间的延长均降低,Peleg模型可较好地(R20.95)模拟渗透脱水过程中的WL。经超声-碱液去皮处理的黄桃果肉得率(0.96 g/g)最高,果干的类胡萝卜素含量(71.14μg/g)和果胶溶出率(0.23 g/g)均高于其它组,色泽保持最好,即ΔE值(2.42)最小,b*最高(42.82),且硬度(2 019.54 g)和咀嚼性(1 087.72)适中。研究表明超声-碱液是一种有效的桃去皮技术。     

超声辅助糖液渗透处理对真空冷冻干燥桃脆片干制品品质及吸湿性的影响

为探究超声辅助糖液渗透处理对真空冷冻干燥桃脆片干制品品质及吸湿性的影响,本实验比较了白桃经4 种糖液（蔗糖、麦芽糖、葡萄糖、低聚异麦芽糖）超声辅助渗透处理后桃片的水分损失率、固形物增加率以及真空冷冻干燥后桃脆片的微观结构、质构特性（硬度、脆度）、吸湿性及玻璃化转变温度。结果表明：与对照组相比,经超声辅助糖液渗透处理的桃片水分损失率、固形物增加率提升,孔隙更加致密且细胞组织发生破裂和结构坍塌,硬度显著提高（P＜0.05）;且超声辅助糖液渗透处理可以降低桃脆片的吸湿性,在相对湿度从0梯度增加到90%的过程中,各处理组样品最终达到吸湿平衡时的质量变化率范围为55.16%～59.63%,对照组为61.43%;与对照组玻璃化转变温度（52.37 ℃）相比,超声辅助麦芽糖渗透脱水处理使桃脆片体系的玻璃化转变温度升高到64.27 ℃。综上,超声辅助糖液渗透处理对桃脆片品质产生影响的同时,也对降低桃脆片吸湿性和改变桃脆片体系玻璃化转变温度具有重要影响,本研究可为改善和提升白桃干制品品质提供技术参考。     

渗透条件对罗非鱼肉渗透-真空微波干燥的影响

为获得罗非鱼片渗透-真空微波干燥前最佳的渗透条件,研究渗透液组成、渗透时间、渗透温度和切片大小对鱼片渗透-真空微波干燥后的含水率、水分活度及品质(收缩率、复水率、色差)的影响。结果表明:鱼片在糖浓度较高的渗透液中,渗透脱水效果较好,但品质不理想;在2 h内鱼片含水率随渗透时间的延长而减少,2 h后渗透效果不明显;渗透温度升高脱水效率增加,但温度过高会破坏组织结构,不利于渗透的进行;切片越大,干燥后含水率越高但品质较差。结论:罗非鱼片渗透-真空微波干燥渗透最佳条件是渗透液组成为20%食盐+10%白砂糖,渗透时间2 h,渗透温度30℃,切片大小为500 mm2。     

渗透脱水对变温压差膨化干燥桃片品质的影响

本文研究了麦芽糖、蔗糖、果糖及葡萄糖4种渗透液对渗透脱水联合变温压差膨化干燥桃片品质的影响。渗透液浓度为50°Brix,渗透温度为40℃,渗透180 min后采用80℃的热风干燥预干燥到20%水分含量(湿基),之后进行变温压差膨化干燥,研究其对桃片质构、膨化度、复水比、色泽、可溶性糖类等的影响,并用扫描电镜对微观结构进行分析。结果表明:与空白对照组相比,麦芽糖渗透脱水改善了桃片的色泽,提高了膨化度及脆度,使桃片具有良好的复水性。扫描电镜结果表明:麦芽糖渗透处理的桃片具有均匀的孔隙结构;蔗糖、果糖及葡萄糖渗透脱水虽提高了桃片的硬度,但降低了膨化度、脆度及复水比,桃片微观结构较致密,且果糖及葡萄糖渗透脱水不利于色泽的改善。经综合考虑,利用麦芽糖进行桃片渗透脱水联合变温压差膨化干燥可获得较优的综合品质。     

芒果片真空预处理联合超声辅助渗透脱水的传质动力学及品质分析

为解决芒果果脯生产过程中传质效率低、加工时间长的问题,该文研究了脉冲真空预处理联合超声辅助渗透脱水对芒果传质动力学、质量特性和微观结构的影响。结果表明：脉冲真空预处理联合超声辅助渗透脱水组的芒果失水率（54.43%）最高,较常规渗透脱水、脉冲真空预处理渗透脱水、超声辅助渗透脱水组分别高45.85%、14.06%、29.38%,增固率（12.81%）较常规渗透脱水、超声辅助渗透脱水、脉冲真空预处理渗透脱水组分别高90.03%、53.43%、32.06%。用Azuara模型拟合渗透脱水过程中失水率和增固率的变化,高回归系数（R2>0.97）和低RMSE表明Azuara模型可以较好拟合芒果渗透脱水过程,预测脉冲真空预处理联合超声辅助渗透脱水组的平衡脱水率、增固率最高,分别为65.06%和23.35%。测定色泽和质构,发现超声辅助渗透脱水组、脉冲真空预处理联合超声辅助渗透脱水组芒果硬度值显著低于常规渗透脱水组和脉冲真空预处理渗透脱水组（p<0.05）,而芒果色泽得到了较好保护。通过扫描电镜的观察,发现超声处理使芒果细胞壁塌陷与变形、细胞横截面积变小、微孔增多。此外,真空对芒果硬度和微观结构的影响均较小。综上,脉冲真空预处理联合超声辅助渗透脱水通过改变芒果细胞结构、增加传质微通道,提高了渗透脱水的效率,缩短加工时间,可以较好保护芒果色泽,但会导致硬度的下降。     

胡萝卜片渗透脱水与真空油炸联合干燥动力学研究

为降低真空油炸果蔬脆片的脂肪含量,提高产品品质,本文研究了胡萝卜片渗透脱水与真空油炸联合干燥动力学,结果表明:随着渗透时间的延长,胡萝卜片的初始水分含量和平衡水分含量逐渐降低,脂肪含量、平衡脂肪含量以及脂肪的吸收速率也逐渐减少,皮尔逊积差相关分析显示:脂肪含量与其初始水分含量具有极显著的相关性(P<0.001);将渗透脱水Fick水分扩散规律和真空油炸一级反应动力学规律相结合,获得了胡萝卜片联合干燥过程中水分与脂肪含量变化的动力学方程,采用非线性回归法确定了方程系数,结果表明方程具有较高的决定系数,能够较好地预测渗透脱水与真空油炸联合干燥胡萝卜片水分和脂肪含量的变化。     

油炸和真空渗透对冻藏风味小龙虾品质的影响

以油炸失重率、渗透增重率、感官评分及质构参数为指标,研究了油炸和真空渗透2个关键工艺对冻藏风味小龙虾品质的影响.结果表明,油炸温度160℃,油炸时间4 min为最佳油炸条件.通过比较常压渗透和真空渗透增重率的变化得出:真空渗透能够有效提高渗透效率;感官评分及质构参数的结果表明,产品最佳的真空渗透时间为10 h.     

Effect of osmotic dehydration with different osmosis agents on water status,texture properties,sugars, and total carotenoid of dehydrated yellow peach slices

The water status, texture properties, sugars, and total carotenoid of dehydrated yellow peach slices pretreated with or without osmotic dehydration (OD) combined with heat pump drying were studied. In this study, different osmotic agents were used, namely, sucrose and isomaltooligosaccharide (IMO) with 30 °Brix for 1, 3, and 5 h. Results showed that the dehydrated samples pretreated by sucrose-OD with the best shape and cell structure showed lower hardness compared to the dehydrated yellow peach slices with IMO-OD pretreatment and without OD pretreatment. Notably, the highest total carotenoid content was found in dehydrated yellow peach slices pretreated by IMO-OD, followed by samples without OD, and samples with sucrose-OD pretreatment. In addition, the lowest a_W (0.517) was obtained in samples with IMO-OD for 5 h, which was beneficial for storage. The assessment of water status and total carotenoid content of dehydrated yellow peach slices showed that IMO-OD pretreatment could better improve the quality of dehydrated fruits. Moreover, the use of IMO in OD treatment was a good alternative to sucrose.     

Sorption Changes Induced by Osmotic Preconcentration of Apple Slices in Different Osmotic Media

Changes in sorption of dehydrated apple slices induced by osmotic preconcentration (OP) in two different osmotic media were studied. A 55% sucrose solution and a 55% solution of 38 DE Corn Syrup Solids (CSS) were used. Sorption isotherms for osmo-vacuum and vacuum dehydrated product were established and fit to the Guggenheim-Anderson-de Boer (GAB) model. Sorption isotherms of both dehydration treatments shifted with respect to control isotherms. OP in sucrose solution resulted in slight reduction of total sugars and gave the most pronounced isotherm shift, while OP in CSS solution resulted in extensive losses of sugars and a lesser isotherm shift. OP resulted in a product with less sugars than the conventionally dried product, especially when CSS were used.     

Electronic Nose to Detect Strawberry Aroma Changes During Osmotic Dehydration

ABSTRACT:  An electronic nose was used to detect the aroma evolution of strawberry fruits, cultivar "Camarosa," during the osmotic dehydration in sorbitol and sucrose solutions. Strawberry slices were subjected to osmotic dehydration at 30 °C for 1, 2, 4, and 6 h using either 60% sucrose or 60% sorbitol solutions. Volatile compounds of fresh and processed strawberry slices were analyzed by electronic nose and gas chromatography. Electronic nose was able to reveal changes in the aroma profile during processing and permitted differentiation between dehydrated strawberry samples obtained by different osmotic treatments. The electronic nose has the advantage of being simple, rapid, and nondestructive. Such characteristics and the promising results of this work suggested that this device could be a useful and innovative tool to monitor strawberry aroma changes during osmotic dehydration, providing real-time information about the effects of processing conditions and allowing the optimization of technological parameters.     

不同小分子糖渗透草莓的传质动力学及对真空冷冻干燥草莓品质的影响

为系统地了解不同小分子糖特别是低聚糖和糖醇对草莓的渗透行为以及不同小分子糖对真空冷冻干燥草莓品质的影响,本研究利用两种数学模型对10 种常见小分子糖（白利度为40 °Brix）的渗透动力学进行拟合,并进一步对渗糖处理后真空冷冻干燥草莓的理化特性进行表征。结果表明,Weibull模型更适用于描述渗糖处理后草莓的可溶性固形物增量（solid gain,SG）,而Peleg模型可以更好地描述草莓的水分去除量（water loss,WL）。经不同糖渗透处理结束后,草莓的SG差异较大,山梨糖醇可以使草莓的SG达到6.84 g/100 g,是低聚异麦芽糖的6.16 倍。此外,渗糖处理的草莓硬度得到普遍提高（94.58%～223.23%）;葡萄糖、果糖、山梨糖醇渗透处理组的脆度分别降低了16.70%、20.74%、41.45%,低聚果糖渗透处理后的草莓质构特性与蔗糖最为接近。综合考虑渗透效率、感官营养品质和生产成本,低聚果糖是蔗糖在果蔬渗透处理方面的一种潜在替代品。     

Effect of Osmotic Dehydration and Vacuum-Frying Parameters to Produce High-Quality Mango Chips

ABSTRACT:  Mango ( Mangifera indica  L.) is a fruit rich in flavor and nutritional values, which is an excellent candidate for producing chips. The objective of this study was to develop high-quality mango chips using vacuum frying. Mango (" Tommy Atkins ") slices were pretreated with different maltodextrin concentrations (40, 50, and 65, w/v), osmotic dehydration times (45, 60, and 70 min), and solution temperatures (22 and 40 °C). Pretreated slices were vacuum fried at 120, 130, and 138 °C and product quality attributes (oil content, texture, color, carotenoid content) determined. The effect of frying temperatures at optimum osmotic dehydration times (65 [w/v] at 40 °C) was assessed. All samples were acceptable (scores > 5) to consumer panelists. The best mango chips were those pretreated with 65 (w/v) concentration for 60 min and vacuum fried at 120 °C. Mango chips under atmospheric frying had less carotenoid retention (32%) than those under vacuum frying (up to 65%). These results may help further optimize vacuum-frying processing of high-quality fruit-based snacks.     

Osmotic Dehydration of Tomato in Sucrose Solutions: Fick's Law Classical Modeling

ABSTRACT:  Osmotic dehydration of tomato was modeled by the classical Fick's law including shrinkage, convective resistance at the interface and the presence of water bulk flow. Tomato slices having 8 mm thickness were osmotically dehydrated in sucrose solutions at 50, 60, and 70 °Brix and at 35, 45, and 55 °C. Other experiments were done in a 70 °Brix sucrose solution at 35 °C with tomato slices of 4, 6, and 8 mm thickness and at different motion levels (velocities 0, 0.053, and 0.107 m/s). Tomato weight, water content, and °Brix of the products were measured as a function of processing time (20, 40, 80, 160, and 320 min). Results showed that temperature, concentration, thickness, and solution movement significantly influenced water loss and sucrose gain during the osmotic dehydration of tomato. The model predicted the modifications of soluble solid content and water content as a function of time in close agreement with the experimental data. Experimental Sherwood number correlations for sucrose and water were determined as Sh _s = 1.3 Re ^0.5 Sc _s^0.15 and Sh _w = 0.11 Re ^0.5 Sc _w^0.5, respectively. The effective diffusion coefficients of water (4.97 10⁻¹¹– 2.10 10⁻¹⁰ m²/s) and sucrose (3.18 10⁻¹¹– 1.69 10⁻¹⁰ m²/s) depended only on temperature through an Arrhenius-type relationship.     

Influence of Modified Atmosphere Packaging and Osmotic Dehydration on the Quality Maintenance of Minimally Processed Guavas

ABSTRACT: The quality of minimally processed guavas ( Psidium guajava L.), osmotically dehydrated and packed under passive modified atmosphere, was evaluated during 24 d of storage at 5 °C. Modified atmosphere packaging (MAP) in polyethylene terephthalate (PET) containers had a strong influence on color preservation and weight loss of the guavas. Significant changes in the texture were found due to osmotic dehydration, but the color of the fresh fruit remained unchanged. Osmotically dehydrated guavas stored in MAP showed good microbial conditions during storage. The combination of storage temperature, modified atmosphere packaging, and the osmotic dehydration process maintained the quality of the guavas during 24 d of storage.     

高压均质对NFC水蜜桃浊汁稳定性及品质的影响

本文采用高压均质技术,探究了均质压力（20~40 MPa）及次数（1~2次）对NFC水蜜桃浊汁的混浊度、离心沉淀率、粒径、Zeta电位等稳定性指标和pH、TSS、总酸、固酸比、还原糖、色泽、总酚、V_C等品质指标的影响。结果表明:高压均质（30~40 MPa/1、20~40 MPa/2）可有效提高NFC水蜜桃浊汁的稳定性,离心沉淀率较未处理组下降13.49%~24.22%,平均颗粒粒径由1853.67 nm降至501.10~665.27 nm,绝对Zeta电位值显著提高（P<0.05）。随着均质压力及次数的增加,浊汁中可溶性果胶含量上升,而残存果胶甲基酯酶活力逐渐降低。高压均质后,浊汁色泽显著改善,L*值升高,褐变指数BI值下降（P<0.05）;30 MPa/1下,品质保持最佳,总酚、V_C含量较未处理组显著提高（P<0.05）,而pH、TSS、总酸和固酸比无变化（P>0.05）;随着均质次数增加,pH、TSS、总酚和V_C含量显著降低（P<0.05）,品质下降。高压均质处理可有效提高NFC水蜜桃浊汁稳定性、抑制褐变,并提高总酚、V_C等营养物质含量。