陶瓷膜在哈密瓜汁微滤除菌工艺中的应用研究

哈密瓜汁对热敏感,为了减少因热处理导致的营养成分和风味物质的损失,采用无机陶瓷膜对哈密瓜汁进行微滤除菌。通过研究三种孔径膜的膜通量、微滤前后哈密瓜汁营养成分的变化及除菌效果,选择最适的膜孔径,并在此基础上选择最适的操作压力和进料温度,从而确定最佳的微滤除菌工艺参数。结果表明:最佳的工艺参数为膜孔径0.2μm,操作压力0.2MPa,进料温度25℃。在此条件下处理的哈密瓜汁透光度可达98.8%,浊度为2.61NTU,菌落总数为13CFU.mL-1,其中大肠菌群、霉菌、酵母菌均未检出。      

Identification of optimal membrane morphological parameters during microfiltration of mosambi juice using low cost ceramic membranes

In this work, experimental investigations were carried out for the identification of optimal membrane morphological parameters (pore size distribution, average pore size and porosity) during microfiltration (MF) of mosambi juice using low cost ceramic membranes. Four different low cost ceramic membranes with different pore diameters (d_m) and porosities (?) were subjected to MF studies to evaluate the effect of d_m and ? on permeation characteristics (permeate flux and juice quality) of centrifuged mosambi juice (CJ) and enzyme treated centrifuged mosambi juice (ETCJ). Subsequently, a convenient factor namely effective permeable area factor (?_md_m²) was evaluated to provide greater insights in the fouling phenomena. Various physio-chemical properties such as colour, clarity, pH, citric acid content, density, total soluble solid (TSS) and alcohol insoluble solids (AIS) were measured for both feed and permeate juice samples to evaluate the effect of ?_md_m² on juice quality. Typical permeate fluxes were observed to vary from 5.78 × 10⁻⁶ to 13.45 × 10⁻⁶ m³/m² s for CJ and 14.07 × 10⁻⁶ to 60.64 × 10⁻⁶ m³/m² s for ETCJ at 82.7 kPa (ΔP) for different membranes whose ?_md_m² varied from 0.249 to 0.783 μm². Among different membrane pore blocking models, flux decline by cake filtration was found to be the best fitted model. The cake filtration model constant (k_c) was found to vary with ΔP and ?_md_m² and was empirically correlated. Phenomenological models were proposed to illustrate the dependency of total hydraulic resistance of membrane on ?_md_m², ΔP and time (t). Based on experimental as well as theoretical investigations, membranes with ?_md_m² up to 0.443 μm² for CJ and 0.294 μm² for ETCJ and a ΔP of 82.7 kPa were recommended for MF of mosambi juice.     

丝瓜汁饮料的研制

介绍了丝瓜汁饮料的加工工艺，分析了架热温度、pH对丝瓜汁澄清效果的影响。     

Clarification of passion fruit juice by microfiltration: Analyses of operating parameters,study of membrane fouling and juice quality

In this study, the performance of two membranes were compared – tubular ceramic and hollow fiber poly(imide) – under transmembrane pressure of 0.5 and 1 bar, for the clarification of passion fruit pulp pre-treated by centrifugation and enzymatic treatment at the concentrations of 150 and 300 ppm. Nutritional and sensorial qualities of the clarified juice obtained were evaluated. Thus, it was possible to observe that the most adequate condition for the clarification of passion fruit pulp was with enzymatic treatment at 150 ppm and its posterior microfiltration at the ceramic tubular membrane of 0.3 μm with transmembrane pressure of 0.5 bar. The fouling mechanism was identified by estimation of model parameters according to a nonlinear regression by Bayesian inference. Analysis of the fouling mechanism results revealed that hollow fiber membrane is controlled by a cake filtration mechanism, and internal pore blocking fouling mechanism controls ceramic tubular membrane.     

Effect of fractal flocculation behavior on fouling layer resistance during apple juice microfiltration

The colloidal material in juice obtained from Red Delicious apples held in cold storage for over 6 months was observed to spontaneously aggregate to form ordered flocculation patterns. These flocculation patterns could be altered by heat treatment and by gelatin or antioxidant addition. The specific resistance of the fouling layer produced by each juice during microfiltration could be qualitatively predicted by examining the structure of macroscopic flocculation patterns. Environmental scanning electron microscopy (ESEM) photos of the various hydrated fouling layers indicated that loose flocs appeared to compress and rearrange on the membrane surface, producing smooth, low porosity secondary membranes. Densely packed cross-linked aggregate networks also formed low porosity structures, once again creating a fouling layer with high resistance. The lowest resistance fouling layers were produced when the flocs were dense enough to resist compression but porous enough to provide pathways for permeate flow. Field emission scanning electron microscopy (FESEM) and ESEM images indicated that, in many cases, the spacial distribution of solids in the microscopic aggregates were reminiscent of those in the macroscopic flocs. Such scaling relationships are typical of fractal systems.     

菠菜冬瓜汁复合饮料的研制

在分析菠菜和冬瓜理化性质的基础上,利用二者营养上的特点,将它们分别榨汁,对其榨汁工艺、调配方法进行了系统的研究,确定了该饮料的最佳制作工艺,该产品的糖、酸含量分别为12％和0.12％。     

Effect of ultrasound,centrifugation, and enzymatic pretreatments on phytochemical properties and membrane fouling during microfiltration of Sohiong (Prunus nepalensis L.) juice

Food Science and Biotechnology - The study aimed to investigate the effects of various pretreatment methods on sohiong fruit juice during the microfiltration process. The ultrasound,...     

苦瓜澄清饮料的开发及其质量评定模型的建立

目的：研究开发一种苦瓜澄清汁饮料,并通过模糊数学处理建立一种饮料的质量评定模型,为生产实践提供技术参考。方法：主要采用感官评定与理化指标相结合对产品进行评定,通过综合指标的比较获得最佳的工艺参数。结果：经过综合指标的比较,得知NaCl用量7％,去苦脱涩15min,在95℃漂烫0．5min条件下获得最高综合指标。结论：建立的质量评定模型使感官指标的主观差别通过数学处理得到有效降低,从而可以对产品进行更客观的评价。     

Storage quality of pineapple juice non-thermally pasteurized and clarified by microfiltration

Microfiltration (MF) is classified as a non-thermal process for the fruit juice industry. It could provide a better preservation of the phytochemical property and flavor of the juice. This work aimed to study the stability of phytochemical properties including vitamin C, total phenolic content, antioxidant capacity (2-Diphenly-1-picrylhydrazyl: DPPH, free radical scavenging capacity and Oxygen Radical Absorbance Capacity: ORAC assays), microbial and chemical–physical (color, browning index, pH and total soluble solid) properties of MF-clarified pineapple juice during storage at various temperatures (i.e. 4, 27, and 37 °C). The juices were clarified by microfiltration using hollow fiber module. The results showed that most of the phytochemical properties and soluble components were retained in the juice after microfiltration. No microbial growth was detected after 6 months of storage. The storage time and temperature did not affect total soluble solids and pH (P > 0.05). The color (L^*) of clarified juice stored at 4 °C was lighter than the juices stored at higher temperature levels (P < 0.05). The phytochemical properties and total phenol content of the juice significantly decreased as storage time and temperature increased (P < 0.05). Vitamin C content was the attribute that affected storage time and temperature most as indicated by reaction rate constant and activated energy. Storage of non-thermally pasteurized and clarified pineapple juice at 4 °C was the most suitable since it allowed the best quality preservation.     

西瓜番茄苦瓜复合汁饮料的研制

精取西反、番茄、苦瓜制取单汁,依据营养互补原则进行调配,确定了复合工艺并对配后的复合汁进行了稳定性实验,得到了一种风味,口感和稳定性俱佳的复合汗。     

In-vitro antioxidant and antibacterial activities of pumpkin,quince, muskmelon and bottle gourd seeds

Ethanol and chloroform extracts of pumpkin, quince, muskmelon, and bottle gourd seeds were studied for in-vitro antioxidant and antibacterial activities. Crude protein and fat contents of all the seeds compared favorably with high protein legumes and high oil containing oilseeds. Ethanol and chloroform extracts of bottle gourd seeds had highest phenolic content. A direct positive relationship between antioxidant activities and extract concentration was observed with the relationship being more pronounced in chloroform extract of quince seeds (R²?=?0.9685 and 0.9829) followed by ethanol extract of pumpkin seeds (R²?=?0.9666 and 0.9685) as per 1,1-diphenyl-2-picrylhydrazyl and hydrogen peroxide (H₂O₂) method, respectively. Seed extracts were also studied for in-vitro antibacterial activity against Salmonella typhii, Enterococcus sp., Escherichia coli, Bacillus subtilis and Staphylococcus aureus. Ethanol extract of pumpkin seeds inhibited the growth of all bacteria; however, both the extracts of quince seeds did not show any activity against S. typhii, E. coli and S. aureus.     

Clarification of tomato juice by cross‐flow microfiltration

Clarification of fruit and vegetable juice is one of the integrated parts of modern industrial juice processing. This paper describes the clarification of tomato juice through microfiltration process. In this regard, the influence of transmembrane pressure (1, 2 and 3 bar), cross‐flow velocity which corresponds with Reynolds number (300, 1500 and 2500) and temperature (30, 40 and 50 °C) on permeate flux and some properties of clarified juice such as colour, turbidity, density, viscosity, pH and total soluble solid have been studied. The results revealed that the investigated parameters had an increasing effect on the permeate flux and colour and the greatest effect on the permeate flux and colour was supplied by cross‐flow velocity. The other permeate properties did not significantly change with variations of the operating parameters. Eventually, the statistical analysis indicated that the interactional effect of cross‐flow velocity and TMP on the permeate flux was significant.     

Changes in blocking mechanisms during membrane processing of pomegranate juice

The effect of pressure, velocity, pretreatment, membrane type and pore size on fouling mechanisms were evaluated. Pomegranate juice was treated with polyvinylidene fluoride (PVDF) 0.22 μm and mixed cellulose ester (MCE) 0.1 μm at different pressures. Cake formation which was the dominant mechanism was formed in the first stages of process and, as the filtration proceeded, intermediate, standard, and complete blocking, respectively occurred at higher pressure (5 kPa). At lower pressure (0.5 kPa) the last mechanism did not occur. Results showed that cake formation was the only mechanism in MCE 0.22 μm, however, others occurred with MCE 0.1 μm and PVDF 0.22 μm. Using MCE 0.22 μm prior to MCE 0.025 μm can reduce the role of cake formation in pore blocking. Evaluation of the impact of velocity showed that at the higher velocity (0.53 m s⁻¹) the complete blocking occurred faster than at the lower velocity (0.09 m s⁻¹).     

PET瓶葡萄汁饮料无菌冷灌装工艺及质量控制

葡萄富含糖、有机酸、矿物质、氨基酸以及多种维生素等,被誉为“水果皇后”,葡萄汁作为一种营养丰富的饮料长期以来受到消费者的欢迎。随着PET瓶包装在世界范围内的蓬勃发展,果汁和软饮料的灌装正在由热灌装向无菌冷灌装进发。液态食品的无菌灌装属于最具发展前景的包装技术领域,它集中了现代制造和控制技术之精华,国内外众多厂商都在此领域开展了多项研究。将无菌冷灌装技术应用到PET瓶葡萄汁饮料的生产中,对提高产品质量,节约生产成本,降低能耗都有很大的益处。     

The quality of orange juice processed by coupling crossflow microfiltration and osmotic evaporation

Crossflow microfiltration (CFM) and osmotic evaporation (OE) were implemented on a semi‐industrial pilot scale to obtain clarified orange juice concentrates at 450 and 620 g kg^?1 of total soluble solids. The characteristics of the juice were then assessed and compared with fresh juice and commercial concentrates. With CFM, most aroma compounds and vitamin C remained in the permeate while the more apolar compounds such as terpenic hydrocarbons and carotenoids were strongly retained by the membrane. With OE, significant losses of vitamin C and aroma compounds occurred at first, with losses progressively decreasing during treatment. Pre‐conditioning the membrane and cold regeneration of the brine reduced losses drastically, with the aroma composition tending towards that of the initial juice. The quality of pulp, a blend of the CFM retentate and OE concentrate, was high and much closer to that of the initial fresh juice than to the commercial thermal concentrate.     

Changes in total phenolic content and color of bottle gourd (<Emphasis Type=Italic>Lagenaria siceraria</Emphasis>) juice upon conventional and ohmic blanching

Plant phenolics exist in a complex matrix and require a high separation capacity for analysis. Bottle gourd (BG) was blanched using conventional thermal and alternate thermal ohmic heating methods using different combinations of temperature (60–90°C) and time (1–5min), and the effect of these methods on total phenolic content (TPC) and color was examined. Complete characterization on the basis of the phenolic profile of unblanched, ohmically blanched, and conventionally blanched samples of BG was studied. Gas chromatography-mass spectrometry and Liquid chromatography-mass spectrometry were used to detect volatile and nonvolatile phenolic compounds, respectively. The color profiles of the unblanched and conventionally and ohmically blanched samples were studied via hunterLab colorimeter using L*, a*, and b* coordinates. The highest increase in TPC was observed at 80°C, 4 min and 90°C, 5min in the case of ohmic and conventional blanching, respectively. The conventionally and ohmically blanched samples both produced desirable green-color retention in comparison to the unblanched samples; however, highest retention was observed in the ohmically blanched samples. The ohmically blanched samples exhibited the maximum extraction of phenolic compounds and better color of BG juice in comparison to the other samples.     

Study of different fouling mechanisms during membrane clarification of red plum juice

In this study, the flux decline mechanisms were identified during membrane clarification of red plum juice at several processing parameters, including pore size, membrane type, transmembrane pressure, temperature and velocity. The results were used to investigate the effect of changes in operating conditions on the intensity of membrane fouling. Also, scanning electron microscopy (SEM) was used for analysing fouling‐layer morphology. These results showed that the main mechanism responsible for membrane fouling was cake formation (over 95% fitness) occurring in the first stage of the process. Intermediate, standard and complete blockings were formed during most of the runs as filtration proceeded. The results also indicated that increasing the temperature from 30 to 40 °C was the most effective factor in decreasing cake‐layer fouling, reducing it by about 66.7%. Furthermore, an increase in processing velocity of up to 0.5 m s^?1 had the greatest effect on intermediate blocking, reducing it by about 86.1%. Also, increasing pressure up to 2.9 bar completely eliminated standard blocking and complete blocking. Finally, microstructure analysis of membrane using SEM confirmed that cake formation had the greatest impact on membrane fouling.     

苦瓜原汁最佳超滤操作条件及滤液品质分析

以寻求提高苦瓜原汁超滤时的渗透流速为目的，用国产UF-中空纤维膜组件进行试验，采用正交试验对超滤操作条件进行优化，分析超滤处理后的苦瓜原汁质量变化。结果表明．在所选定的因素水平范围内，苦瓜原汁超滤时渗透瘴速量高的优因素水平组合为膜截留相对分子质量60000．操作温度40℃，操作压力0．06MPa；超滤处理后．原汁的苦瓜固有滋味和品质得到较好保留，国产超滤膜用于苦瓜原汁工业化生产是可行的。