High performance liquid chromatographic determination of soluble carbohydrates in commercial drinks

High performance liquid chromatography was carried out to determine the soluble sugar content in canned soft drinks and commercial fruit juices stored in different types of containers. The total amount of sugars ranged from 9.2 to 13.5 g 100 ml^?1 for the soft drinks, 10 to 14 g 100 ml^?1 in fruit nectars and 3 g 100 ml^?1 in tomato juice. The individual sugar content of soft drinks varied between different batches, although the total amount remained fairly constant for each kind of drink or juice. Only in tomato juice where sucrose was not present, did the values for glucose and fructose remain constant.     

果葡糖浆在果汁饮料中的应用研究

对使用蔗糖与果葡糖浆生产的果汁饮料的成分进行了分析，比较了两类产品的糖成分和感官差异。结果表明：使用蔗糖生产的果汁饮料与使用果葡糖浆生产的果汁饮料比较，果葡糖浆对产品色泽的影响与蔗糖没有明显区别；但在产品风味方面，后者甜味消失快，果香味与酸味变浓；在果汁生产过程中，采用果葡糖浆部分替代蔗糖的产品风味不受影响．     

Engineering factors in the production of concentrated fruit juices 1. Fluid physical properties of orange juices

This study presents the essential physical properties (boiling-point rise, viscosity, density, specific heat) of orange juices, necessary for the optimization of processing units for concentrated orange juices.
When these physical properties were correlated with the sucrose content of juice, expressed as degrees Brix, in the range 10–65° Brix and compared with those of aqueous sucrose solutions, significant differences were observed in respect of viscosity, specific heat and elevation of boiling point.     

EFFECT OF TEMPERATURE ON VISCOSITY OF FRUIT JUICES AND PUREES

SUMMARY: The viscosities of selected fruit juices and purees were measured with a coaxial-cylinder viscometer in the temperature range 20–70°C. Depectinized apple juice and Concord grape juice were Newtonian fluids at all concentrations and their viscosity decreased considerably at higher temperatures. Cloudy apple and orange juices changed from Newtonian to pseudoplastic at concentrations higher than 50 and 20° Brix. respectively. Temperature had a smaller effect on viscosity of cloudy juices than of clear juices. The apparent viscosity of fruit purees (pseudoplastic fluids) decreased slightly at higher temperatures. The activation energy for flow increased with the juice concentration and decreased with the presence of suspended particles in the fruit product. The data and conclusions are useful in the design and operation of efficient food-processing equipment.     

Optimisation of osmotic dehydration of 'Tommy Atkins' mango fruit

Osmotic dehydration of mango in sucrose solution as influenced by temperature (30–50 °C), immersion time (60–150 min) and solution concentration (40–60% w/w) was studied through response surface methodology. Responses of water loss and solid gain were fitted to polynomials, with multiple correlation coefficients ranging from 0.72 to 0.95, respectively. The fitted functions were optimised for maximum water loss and minimised incorporation of solids in order to obtain a product resembling non-processed fruit. Optimum conditions to obtain water removal >25% with solid uptake lower than 6% could be obtained using a 44% (w/w) sucrose solution concentration, temperatures up to 38 °C and immersion times up to 80 min.     

Inulin and Sugar Contents in Helianthus tuberosus and Cichorium intybus Tubers: Effect of Postharvest Storage Temperature

ABSTRACT: Inulin, sucrose, fructose, and glucose contents in tubers of Helianthus tuberosus (Jerusalem artichoke) and Cichorium intybus stored at different temperatures (-18, 4, and 18 °C) after harvesting were followed. Inulin content in both tubers decreased during storage. In C. intybus this decrease was associated with increases in glucose and fructose contents. In H. tuberosus the fructan fraction having molecular weight between 800 and 1200 increased after sucrose reached its maximum content [1.3–10⁻¹ g(g d.w.)⁻¹] in tubers stored at 4 °C. Fructose-to-glucose ratio was followed in H. tuberosus tubers harvested at different times; samples from plants subjected to different fertilization treatments were used. This parameter can be used for choosing the harvest date since it is related to the disappearance of the fructan fraction having molecular weight higher than 1200.     

Potential use of physical measurements including ultrasound for a better mango fruit quality characterization

The potential use of ultrasound measurements, combined with other physical measurements, has been investigated. The good relationship between soluble solids content (SSC) and ultrasonic wave velocity reported in the literature being confirmed by our study, our main goal was to evaluate the added value of ultrasound measurements around 25 MHz for the determination of biochemical compounds responsible of organoleptic quality of mangoes. Among the main sugar constituents of mango juice, only sucrose content prediction was improved by combining SSC and ultrasonic waves velocity using a PLS model (R² = 0.81, RMSECV = 12.3, bias = 0.10, RPD = 2.3) when compared to the linear model with SSC only (R² = 0.75, SEP = 14.05, bias = 0.08). The same conclusion was obtained for titratable acidity PLS model using whole fruit hardness, SSC and ultrasonic wave velocity (R² = 0.82, RMSECV = 1.84, bias = 0.02, RPD = 2.4) compared to the linear model with fruit hardness only (R² = 0.78, SEP = 2.07, bias = 0.02). However, the added value of ultrasound measurements was not always found to be significant (P = 0.05) when a Wilcoxon statistical tests was conducted on the residuals of the linear and PLS models for both sucrose and titratable acidity.     

VACUUM-PUFF FREEZE DRYING OF TROPICAL FRUIT JUICES

SUMMARY— A study was made to develop high Quality juice powders from four tropical fruits. Guava and mango puree, passion fruit and pineapple juice were dehydrated in a vacuum-puff freeze-drying process. Sucrose in amount (25–40%) approximating nectar formulations was mixed with single-strength juice or puree samples, blended 2 min, and frozen. Freezing temperatures of various samples were measured in a constant temperature bath of −21.6°F. Samples initially frozen in blast freezers at −40°F or 0°F with 0.25–1.0 lb/ft² were vacuum-puffed and freeze dried on aluminum trays at 50μ Hg and 120–130°F shell temperature for 6–9 hr to 1–2% moisture. Puffing was affected by (1) rapid freezing of the juice-sucrose mixture; (2) artificially entrapping some gas in the mixture before freezing; (3) changing the pressure or temperature in the chamber to effect gas expansion; and (4) increasing the mixture viscosity to limit bubble sizes. Results of drying over 160 different samples showed that: (1) added sucrose to give a 40° 5° Brix in the mixture resulted in a stable 'puffed' structure; (2) several permissible calcium salts and silica at 0.1–0.5% (w/w) added to the mixture before drying, improve the free-flowing properties of the dried product. Process variables are discussed and typical sample compositions given.     

牡丹花脯超声渗糖工艺优化及其质构特性的对比分析

以牡丹花为原料,利用超声波的强化传质特性制备牡丹花脯,优化超声渗糖的工艺条件,并对比分析不同渗糖方式对牡丹花脯质构特性的影响。结果表明,超声渗糖的最佳工艺条件为:超声功率110 W、渗糖时间40 min、蔗糖浓度40%,渗糖后花脯含糖量为32.96%,且花脯渗糖速率得到提高;采用超声渗糖法制备的牡丹花脯的硬度值为16.069N,凝聚性为0.606,弹性为0.876,胶着性为9.738N,咀嚼性为8.530mJ,且超声渗糖花脯的硬度、胶着性及咀嚼性与真空及常压渗糖花脯对比均有显著性差异,呈现出良好的质构特性。     

我国市售饮料中游离糖含量研究

目的 了解我国市售饮料中游离糖及其单体的含量,为游离糖摄入及其风险评估提供基础数据,为制定完善相关政策提供科学依据.方法 根据我国饮料行业产销量并结合地理分布,2015年采集9类饮料样品共计708份;根据美国分析化学家协会(AOAC)2000.17方法,以高效离子色谱-脉冲安培检测法测定其中的单糖和二糖(葡萄糖、果糖、...     

Effects of tangential microfiltration and pasteurisation on the rheological,microbiological, physico‐chemical and sensory characteristics of sugar cane juice

The aim of this study was to determine the physico‐chemical, microbiological, rheological and sensory characteristics of sugar cane juice with passion fruit pulp (5% w/w) added and which had been submitted to microfiltration and pasteurisation (90 °C/30 s; 95 °C/30 s) processes. The results showed that the juices obtained after the microfiltration and pasteurisation processes had low microbial counts. The microfiltered juice showed a reduction in the soluble solids, acidity and vitamin C content (P = 0.05), while the pasteurised juice showed no change in these parameters (P > 0.05) in relation to the natural sugar cane juice, with the exception of vitamin C, which was not detected after the thermal treatment. In relation to the rheological properties, Newtonian behaviour was observed for both microfiltered and pasteurised juices. The sensory tests on a hedonic scale showed good acceptance of both juices (microfiltered and pasteurised).     

PASSION FRUIT STARCH AND EFFECT ON JUICE VISCOSITY

Starches in the juices of yellow passion fruit, Passiflora edulis f. flavicarpa , and purple passion fruit, P. edulis f. edulis , were isolated and characterized. Starch granule sizes for the yellow variety (7.8 μm) and purple variety (6.4 μm) were similar. Gelation temperature ranges for the yellow variety (58.5–67.0 ° c) and purple variety (58.5–66.5 ° C) were also similar. The amylose content was slightly higher in the yellow variety (8.7%) than in the purple variety (5.8%). Viscosity differences between juices of the two varieties after treatment with heat and α-amylase were attributed to differences in pH and starch content between the yellow variety (pH 2.8, 0.06% starch) and the purple variety (pH 4.2, 0.74% starch). α-amylase was effective in reducing the viscosity of passion fruit juice in which the starches are gelatinized.     

Effect of temperature on chlorophyllase activity, chlorophyll degradation and carotenoids of Cavendish bananas during ripening

Changes in chlorophyllase activity, chlorophyll and carotenoid content of Giant Cavendish banana fruit peel during ripening were measured at tropical temperatures (30–34°C) and at 20°C to relate them to the greenish and yellow colours of the fruit ripened at these temperatures. At 30–34°C bananas remained green on ripening due to incomplete chlorophyll degradation while at 20°C complete degreening occurred and fruits turned yellow. Peel total carotenoid content remained constant during ripening and did not change with temperature. Free xanthophylls decreased while xanthophyll esters increased on ripening. Chlorophyllase activity increased during ripening and paralleled the respiratory climacteric, although activity was not consistently related to the differential degradation of chlorophyll at these temperatures. Exogenous application of ethylene and ethrel accelerated ripening, but had no effect on chlorophyllase levels, chlorophyll degradation and carotenoid content of bananas ripened at either 30–34°C or at 20°C.     

Effect of permeable coatings on the storage life of fruits.

A permeable membrane coating can be produced on fruit surfaces by dipping in an aqueous dispersion of Pro-long, a mixture of sucrose esters of fatty acids and the sodium salt of carboxymethylcellulose. Mangoes (Mangifera indica L. cv. Julie) were treated with 0.75 and 1.0% w/v aqueous suspensions of Pro-long and stored at 252°C/85–95% RH. Treatment with 0.75% Pro-long significantly increased the storage life of mangoes, retarding ripening and reducing weight loss, without adversely affecting the sensory quality of the fruit. Treatment at 1% resulted in increased ethanol formation in the pulp of some mangoes.     

不同渗糖方式对红宝石李果脯品质的影响

以红宝石李为原料,采用常压、真空、超声波和微波3种渗糖加工方式,研究不同渗糖工艺下红宝石李果脯的色泽、质构特性、总糖含量、复水性、水分构成、滋味以及果脯品质的感官变化。结果表明:采用真空渗糖技术能够显著提高产品的亮度,微波渗糖得到的产品色泽较差;超声波渗糖的产品复水率、硬度和韧性显著偏高(P <0. 05),总糖含量最高;微波和超声波渗糖制备果脯中结合水的相对含量显著偏高(P <0. 05)。电子舌滋味测定结合感官评价超声波渗糖制备的果脯滋味最佳。     

贮藏温度对采后龙眼果实糖代谢及其相关酶活性的影响

研究采后不同贮藏温度(25、15、4℃)对'石硖'龙眼果实糖组分及相关酶活性的影响.测定龙眼果肉可溶性固形物含量(SSC)、3种主要糖含量和糖代谢相关酶活性的变化,对不同贮藏温度各个时期样品进行主成分分析和载荷因子分析,并对各指标进行相关性分析.结果表明:25℃贮藏的龙眼SSC下降最快,贮藏8 d即从23.5％降至22...     

Drying and Crystallization of Sucrose Solutions in Thin Films at Elevated Temperatures

ABSTRACT: Thin sucrose films were dried over 30-min periods during which sucrose crystal growth rates were monitored by videomicroscopy. Drying parameters and sucrose solution properties were varied to determine their effect on initial sucrose crystal growth rates. Growth rates increased by a factor of 4.5 as temperature increased from 40 to 70 °C. Varying initial sucrose concentration (70 to 80%) and drying air velocity (2 to 5 m/s) produced no change in crystal growth rates. Increases in film thickness from 150 to 450 μm and the presence of moisture in the drying air reduced growth rates by 33% at 70 °C, but had no effect at 50 °C. The addition of invert sugar (up to 5%) reduced growth rates by a factor of 2 to 3.     

超声波对糖溶液物化特性的研究

研究了果糖、葡萄糖、蔗糖、麦芽糖、乳糖五种糖溶液的声速-浓度关系,结果表明:糖溶液中声速与浓度呈极显著正相关,得到的二次回归方程的回归系数大于0.9970。同时比较了声参量和密度对糖类型的辨别性,结果表明:超声检测方法对糖的种类具有更好的辨别性。探讨了声特性与糖分子结构以及糖分子与水分子的水合作用与超声参量之间的关系,表明超声参量可用于对糖溶液物化特性的研究。     

响应面试验优化超声渗糖制备野生软枣猕猴桃果脯工艺及其质构分析

采用超声渗糖制备野生软枣猕猴桃果脯并进行质构分析,探讨超声波对渗糖效果的影响。以含糖量为考察指标,通过响应面法分析优化超声渗糖条件为超声渗糖时间5.1 h、超声功率140 W、渗糖液糖度54 °Brix,此条件渗糖后的果脯湿基含糖量为32.27%,提高了果脯的渗糖速率。全质构分析和穿刺测试结果表明,采用超声渗糖法制备的软枣猕猴桃果脯的硬度值为4 345 g,咀嚼性为52.73 mJ,凝聚性为0.22 mJ,黏性值为58 g,脆性值为435.5 g,其主要质构指标与对比蜜枣果脯接近,感官质量优于真空渗糖软枣猕猴桃果脯。     

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.