超滤澄清工艺在果汁加工生产中的应用

果汁类型大致上分为清汁、混汁和带果肉果汁三类。目前国际上加工成清汁的品种主要有苹果汁、葡萄汁和一些浆果汁。加工成混汁或带果肉果汁的有柑桔汁、菠萝汁、桃、梨、杏和热带水果类,如芒果、西番莲等。     

壳聚糖在菠萝汁澄清中的应用研究

通过实验研究了壳聚糖澄清菠萝压榨果汁的最优条件为:用脱乙酰度90%的壳聚糖,加入量0.6g/L,然后原果汁于40℃保温30分钟,果汁pH为自然pH值,制得的清汁透光率达到98%;贮藏实验结果表明低温有利于清汁的贮藏稳定,常温下整个实验贮藏期间果汁透光率都大于90%;实验还表明壳聚糖对菠萝果汁的澄清不影响果汁的营养价值。     

壳聚糖澄清猕猴桃果汁的研究

通过光学显微镜观察壳聚糖澄清猕猴桃果汁过程中，果汁的粒子状态以及粒径分析仪分析壳聚糖澄清猕猴桃果汁前后果汁中粒子的粒径分布，研究壳聚糖澄清猕猴桃果汁的过程。分别用具有不同脱乙酰度和相对分子质量的四种壳聚糖澄清猕猴桃果汁，研究了不同壳聚糖的澄清效果和澄清后猕猴桃清汁的贮藏稳定性。     

苹果加工的SMART概念

加工苹果汁和浓缩苹果清汁,酶制剂是必不可少的。酶有2个功能：提高出汁率和将果汁澄清。作为水果加工用酶的市场领导者,帝斯曼食品配料部拥有完整的酶制剂产品系列,为果汁加工带来了全套的解决力案。SMART概念就是其中之一——它是一个酶工具箱,     

壳聚糖在柚子汁澄清中的应用

研究壳聚糖澄清柚子汁的最优条件为:用脱乙酰度90%的壳聚糖,以0.6 g/L加入量于柚子原果汁中,40℃保温30 min,果汁p H为自然p H,制得的清汁透光率达到98%;贮藏试验结果表明低温有利于清汁的贮藏稳定,常温下整个试验贮藏期间果汁透光率都大于90%,试验还表明壳聚糖对柚子汁的澄清不影响果汁的营养价值。     

模糊数学综合评判优化甘蔗龙眼火龙果猕猴桃复合发酵饮品配方

以甘蔗、龙眼、火龙果、猕猴桃的清汁为原料开发一款亚热带水果复合发酵饮品。通过单因素分析,探讨了甘蔗清汁、龙眼清汁、火龙果清汁和猕猴桃清汁添加量对产品感官品质的影响,并以口感、色泽、香气、形态为评价因素,结合L₁₆(45)正交试验方案,以模糊数学综合评判优化甘蔗清汁、龙眼清汁、火龙果清汁、猕猴桃清汁复合发酵饮品配方。结果表明:最佳发酵优选组合为甘蔗清汁25 mL、龙眼清汁50 mL、火龙果清汁20 mL、猕猴桃清汁12 mL,在此组合下,定量复配发酵制得的饮品综合感官品质最为理想。本研究结果可为利用甘蔗中的天然糖分为主要碳源的亚热带水果复合发酵工艺提供参考和理论依据。     

饮料加工

马蹄甘蔗汁饮料的研制，甜玉米饮料加工技术，玫瑰茄胡萝卜复合饮料的加工工艺，如何加工芦荟清汁型饮料，无花果果汁澄清方法的筛选研究……     

不同澄清工艺对柠檬果汁品质影响及柠檬苦素贮存期间降解速率预测模型建立

为优化柠檬NFC果汁的加工工艺,本研究比较了琼脂絮凝法、酶解-吸附联用法、酶解-絮凝联用法和冻融细胞破碎法对柠檬原果汁的澄清效果,并建立了柠檬原果汁及经不同澄清工艺处理获得的柠檬清汁贮存期间柠檬苦素降解模型。结果显示,四种澄清工艺均可明显提高柠檬果汁的透光度并维持品质;酶解-吸附联用法对柠檬原果汁的澄清效果要优于其它三种方法,但显著降低了清汁中总酚和抗坏血酸含量(P<0.05),该法最优参数为果胶酶添加量0.3%,纤维素酶添加量0.15%,酶解时间2 h,活性白土添加量为4%;经澄清处理的柠檬清汁样品在贮存期间柠檬苦素含量降解的速率常数(k)与Arrhenius数学模型的相关性高,且模型为一级反应动力学方程。经酶解-吸附联用法澄清处理的柠檬清汁中柠檬苦素降解反应活化能(Ea)显著(P<0.05)低于其余三种澄清处理法,说明该体系下柠檬苦素更易发生降解。因此,琼脂絮凝法、酶解-吸附联用法、酶解-絮凝联用法和冻融细胞法均可用于柠檬NFC原果汁的澄清,但在实际果汁生产中应考虑使用对功能性物质破坏小的方法。     

壳聚糖澄清猕猴桃果汁对果汁成分影响的研究

首先采用离子交换色谱分离壳聚糖k,得到三个壳聚糖组分(壳聚糖a、b、c)。再对未经离子交换色谱分离的壳聚糖k和经离子交换色谱分离所得的三个组分壳聚糖a、b、c澄清猕猴桃果汁前后猕猴桃果汁中化学成分变化和澄清后猕猴桃果汁的透光率、色泽的研究。可以得出,1:未经离子交换色谱分离的壳聚糖k和经离子交换色谱分离所得的三个组分壳聚糖a、b、c都可以有效的澄清猕猴桃压榨果汁,透光率达到94.6%以上;2:壳聚糖k和壳聚糖a、b、c对澄清后猕猴桃清汁的色泽有不同的影响,壳聚糖k澄清后的猕猴桃清汁色泽浅,壳聚糖c澄清后的猕猴桃清汁色泽较深;3:壳聚糖k和壳聚糖a、b、c澄清猕猴桃压榨果汁前后果汁中的可溶性固形物和VC含量相同,不影响猕猴桃果汁的营养价值;4:壳聚糖k和壳聚糖a、b、c澄清猕猴桃压榨果汁前后猕猴桃果汁中总糖、还原糖、蛋白质、总酚含量都有所变化,但是不同壳聚糖对果汁中成分的影响是不同的。     

枇杷清汁的研制

研究确定了以早钟六号和解放钟枇杷为原料制备枇杷清汁的加工工艺及其参数,分析了两品种间的加工差异性和成品中的游离氨基酸含量。结果表明,枇杷破碎打浆时,加入0.3～0.5g/kg的抗坏血酸可有效抑制枇杷浆汁的氧化褐变;采用酶解取汁工艺可提高枇杷的出汁率达16%以上,并利于果汁澄清;枇杷原果汁40%,平衡糖含量(质量百分比)为10%,平衡酸含量(质量百分比)为0.38%是最受欢迎的枇杷清汁的配比。     

绿豆芽苹果复合果汁的研制

以绿豆芽和苹果为原料,研制复合型澄清果汁饮料。用两种汁液比、汁液量、蔗糖量、柠檬酸量为因素，采用4因素3水平L9（3^4）正交实验设计，筛选最佳实验配方。结果表明，最佳配方为绿豆芽：苹果汁为1：1、汁液量22%、蔗糖用量7%、柠檬酸用量0.02%。     

Comparative study of phenolic content and antioxidant activity of strawberry puree,clear, and cloudy juices

The aim of this study was to determine the concentrations of phenolic compounds and their antioxidant activity in different kinds of juice: clear, cloudy, and puree which were made from three different strawberry cultivars (Elkat, Kent, and Senga Sengana). The anthocyanins, p-coumaric acid, ellagic acid, quercetin, keampferol derivatives, (+)-catechin, proanthocyanidins content and degree of proanthocyanidin polymerization, were determined both in the fresh and after 6 months of storage at 4 and 30 °C. Freshly produced juices contained higher amounts of phenolics, especially of anthocyanins and proanthocyanidins, than those stored for 6 months at 4 and 30 °C. The processing of the clear juice showed the higher loss of all phenolic compounds. The antioxidant capacity was the smallest for clear, and the highest for the puree juices. This was assessed by measurements made with different antioxidant activity assays: ABTS and FRAP. The puree of strawberry juice had significantly higher levels of the phenolic compounds and showed more antioxidant activity than the clear and cloudy juices, before and after storage in all strawberry cultivars.     

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.     

Sensory quality and compositional characteristics of blackcurrant juices produced by different processes

Effects of enzymatic and non-enzymatic juice pressing on key orosensory and chemical quality factors of blackcurrant juices were studied in laboratory scale using berries of five different cultivars (Mortti, Mikael, Marski, Ola and Breed15). Enzymatic processing increased the juice yield by 10–22% and the content of various phenolic compounds in juice by 4–10-fold as compared to the non-enzymatic process. Higher intensity of the mouth-drying astringency of the enzyme-aided juice was the most significant orosensory difference between the processes. Juices of different blackcurrant cultivars varied in sweetness, sourness and bitterness. The most intensive sensory attributes of the juices were sourness and puckering astringency regardless of processing method. They correlated positively with each other and were contributed by acid content and pH. In enzyme-aided juices, the contents of flavonol glycosides and hydroxycinnamic acids were associated with mouth-drying astringency, and sugar/acid ratio correlated with sweetness. These correlations were less clear in non-enzyme juices possibly due to lower content of phenolic compounds and the high content of pectin.     

Free sugars determination by HPLC in pineapple products

Free sugars have been determined by HPLC in fresh pineapple fruit, freshly extracted pineapple juice (home-made), pineapple juice concentrate (for industrial use), commercial pineapple juices and nectars. In natural samples, intermediate products and commercial juices the dominant sugar was sucrose, followed by fructose and glucose, both of which were found in similar concentrations. However, the sugar content of nectars analyzed was highly variable. The presence of maltose in nectar samples is a clear indication of the addition of sugars from corn syrup. We have found a fructose/glucose ratio close to 1, and the coefficient fructose plus glucose/sucrose close to 1, both of which are a good index of authenticity of pineapple juices.     

SUPERCRITICAL CARBON DIOXIDE PERCOLATION OF SEA BUCKTHORN PRESS JUICE1

Sea buckthorn press juice was subjected to percolation with supercritical carbon dioxide at 13.8 and 27.6 MPa. Control juice was not percolated. Percolation extracted about 81 % of the oil present in the press juice, lightened the orange color compared with the control juice, and changed the character of the juice as perceived by observers. Percolated juices had no visible particulate that adhered to glass surfaces as did the control juice. All juices were perceived by taste panelists as to be very sour, and it was decided to sweeten the juices with 10% sucrose before proceeding with sensory evaluations. Control juice was more yellow and thicker in consistency than the percolated juices which did not differ from each other. Juices prepared by 27.6 MPa percolation were more frequently reported as having citrus and peach‐like quality attributes compared with either of the other two juices. Analytical values for protein, oil, moisture, titratable acidity and pH were reported for the juices. Light microscopy indicated a lower oil content in the percolated juices and that the particle sizes were smaller in the percolated juices. Some morphological characteristics of the particles in both juice types are described.     

Chemical-Sensory Characteristics and Consumer Responses of Blackcurrant Juices Produced by Different Industrial Processes

Four blackcurrant juices were produced in industrial scale to study the impact of different processes on the sensory-chemical characteristics and hedonic responses of consumers. Two juices were produced without enzymatic treatment of berries with or without further clarification and filtration. The residue was re-pressed using an enzyme-aided processing method to yield the third juice. The forth juice was obtained by conventional enzymatic processing of berries. The enzyme-aided juices were more astringent and bitter than the non-enzymatic juices, mostly due to higher contents of phenolic compounds, lower contents of sugars, and lower pH and sugar/acid ratio. Higher degree of polymerisation and lower procyanidin/prodelphinidin ratio in proanthocyanidins also contributed to higher intensities of astringencies of the enzyme-aided juices. Overall, the non-enzyme-aided juices received higher ranking in flavour, the enzyme-aided juices in odour. Sweetness, roundness, berryness, and high-sugar content were positive drivers for liking, whereas astringency, bitterness and high content of phenolic compounds were negative drivers. High-pectin content masked the astringency and bitterness of the juices. Higher liking ratings correlated with the previous consumption of blackcurrants and higher age of consumers. Gender showed clear impact on consumer rating of the juices. Males liked more enzyme-aided juices than females and vice versa with the juices produced without the use of enzymes. The processes investigated by this study maybe optimised for commercial production of juices targeted for different consumer groups.     

Kiwifruit Juice Processing Using Heat Treatment Techniques and Ultrafiltration

Heat treatment of kiwifruit juice caused formation of a heavy protein precipitate. Celite filtration removed the precipitate giving a clear, heat-stable juice which could be readily concentrated and reconstituted. Hollow fibre ultrafiltration was used to clarify and nonthermally sterilize kiwifruit juice. Virtually all the soluble proteolytic enzyme, actinidin, remained in the retentate although there was some loss of enzymatic activity. Some sedimentation was observed in both conventionally prepared and ultrafiltered juices prepared in the 1980 season, but not in 1981. A procyanidin: protein haze formed immediately in certain clarified kiwifruit juice: apple juice blends.     

OPTIMUM QUALITY PARAMETERS OF MUSCADINE GRAPE JUICES, BEVERAGES, AND BLENDS

Cold- and hot-pressed juices from black and bronze muscadine grapes were tested to determine optimum Brix/acid ratios, optimum juice level in beverages, and optimum blend ratios with other fruit juices. The optimum Brix/acid ratio, regardless of cultivar or process, was approxi-mately 30 with. an acceptable range from 25. to 35. Increased sweetness due to sugar addition was perceptible, even when balanced with addition of acid. Optimum dilution was dependent upon cultivar and process. Red hot-pressed juice was most acceptable at a 25% juice level, when Brix/acid was adjusted to 30. Optimum blends with fruit juices varied with muscadine juice color and process. Best blends were muscadine juices and commercial grape juices, orange juice, and pineapple juice. Muscadine grape-grapefruit juice blends had poor acceptability.     

Effects of Juice Matrix and Pasteurization on Stability of Black Currant Anthocyanins during Storage

The effects of juice matrix and pasteurization on the stability of total phenols and especially total and individual anthocyanins were examined in black currant (BC) juice and mixtures with apple, persimmon, and peach juices at 4 °C and 20 °C. Total phenol content decreased in all juices at both temperatures but there was a trend to lower levels in unpasteurized over pasteurized juices. Differences in the decline of total anthocyanins between pasteurized and unpasteurized juices varied according to the juice type and the storage temperature. At 4 °C storage, anthocyanins declined in all juices according to pseudo 1st‐order kinetics and there were only small differences in the rates between pasteurized and unpasteurized juices. However, at 20 °C, although pasteurized and unpasteurized BC juices and pasteurized mixed juices followed pseudo 1st‐order kinetics, there was a different pattern in unpasteurized mixed juices; a rapid initial decline was followed by a slowing down. The effect of the added juice on anthocyanin decline was also different at either temperature. At 4 °C, the anthocyanins decreased faster in mixed juices than BC juice alone, but at 20 °C, at least in pasteurized mixed juices, the decline was similar or even slower than in BC juice; there were only small differences among the 3 mixed juices. At 20 °C, in pasteurized and unpasteurized BC juices, the rate of decrease was essentially the same for all 4 individual anthocyanins but in the mixed juices the 2 glucosides decreased significantly faster than the 2 rutinosides.