REVERSE OSMOSIS CONCENTRATION of APPLE JUICE: FLUX and FLAVOR RETENTION BY CELLULOSE ACETATE and POLYAMIDE MEMBRANES

Apple juice was concentrated in a pilot scale reverse osmosis unit using two commercial spiral wound cellulose acetate membranes with 97% (CA-97) and 99% (CA-99) NaCl rejection ratings and an experimental polyamide (PA-99) membrane with 99% salt rejection rating. Flux and concentration rates were higher for the PA-99 membrane than for the CA membranes. Gas chromatographic analysis of feed, permeate, and concentrate samples was undertaken and a mass balance of odor-active volatiles was performed. the PA-99 membrane retained 45% of the total odor-active volatiles while the CA-99 retained 23 %. Acetates were not found to increase when apple juice was concentrated with the cellulose acetate membrane. Retention of individual aroma compounds for the CA-99 and PA-99 membrane was rationalized using polar, nonpolar, and steric parameters.     

Composition of Some Organic and Inorganic Compounds in Reverse Osmosis-Concentrated Citrus Juices

Orange, grapefruit and lemon juices were concentrated over twofold in a pilot scale reverse osmosis (RO) process using a commercially available membrane system. Major sugars, acids, vitamin C, aroma volatiles and over 20 minerals were examined in feed, concentrate and permeate streams. Typically, 15–20 aroma compounds were identified in feed juices and concentrates. Compared with less volatile compounds (e.g., ethyl butyrate, limonene), poorer retention during processing was noted for more volatile molecules (methanol, acetaldehyde, ethanol). °Brix of membrane concentrates were orange (25.3°B), grapefruit (25.1°B) and lemon (22.5°B). Vitamin C was rejected efficiently by the membrane. Mineral analyses showed similar elemental contents in feed and concentrate and insignificant concentration in permeate streams.     

Reverse Osmosis Concentration of Aqueous-Phase Citrus Juice Essence

Dilute aqueous essences of 2 to 20% ethanol obtained from commercial orange juice evaporators when concentrated to 31% ethanol by reverse osmosis resulted in increased concentration of the small aroma molecules and acetaldehyde. Rejection of ethanol varied from 90% at 2% ethanol to 40% at the highest concentration achieved (31%). Acetaldehyde rejection varied from about 65% at 2% ethanol, to an extrapolated low value of 25% at 31% ethanol. Rejection was generally greater than 85% for larger aroma molecules, e.g., ethyl butyrate, hexanal and terpenes. Permeate flux rates followed a first order decay with increasing ethanol concentration, from greater than 300 at 0.01% ethanol to 26 L/H/module at 31% ethanol, 8.3 MPa, 30°C.     

柠檬汁中游离态和键合态萜类化合物的研究

应用Amber lite XAD-2柱吸附,选用不同的溶剂洗脱从柠檬汁中提取和分离出游离态和糖苷键合态的香气组分。键合态组分经β-D-葡萄糖苷酶水解释放出挥发性糖苷配基。用气相色谱和质谱联用仪在游离态和键合态中分别检出了16种和9种萜类化合物,其中有5种为首次在柠檬香气中发现。酶法水解对柠檬香气有明显的增香作用。HPLC分析苷元可能是葡萄糖和鼠李糖。     

CONCENTRATION OF ONION JUICE VOLATILES BY REVERSE OSMOSIS AND ITS EFFECTS ON SUPERCRITICAL CO2 EXTRACTION

Supercritical carbon dioxide extraction of onion oil at moderate temperatures produces aproduct which is characteristic of the fresh flavor of onions. It was attempted to improve extraction efficiency by concentrating the onion juice by reverse osmosis prior to supercritical CO₂ extraction. Reverse osmosis was carried out for all combinations of 600, 700, and 800 psi feed pressure and 25 and 35C. The juice was concentrated to 18 ^oBtix and then subjected to supercritical CO₂ extraction. The effect of concentration on the extraction process was evaluated by comparing the yields of extracts from concentrated juice with that of single strength juice. Concentration of onion juice by reverse osmosis improved the efficiency of supercritical CO₂ extraction of onion oil and did not alter its characteristic fresh aroma.     

Electrodialysis Desalination and Reverse Osmosis Concentration of an Industrial Mussel Cooking Juice: Process Impact on Pollution Reduction and on Aroma Quality

ABSTRACT: An industrial mussel cooking juice was treated by a 3-step process to produce a natural aroma concentrate and a cleaned water stream. The juice was centrifuged before being desalinated by electrodialysis and then concentrated by reverse osmosis. As a result of this combined process, most of the physicochemical properties of the reverse osmosis permeate were reduced below the discharge standards. The concentrate was examined by a trained sensory panel (triangular tests, sensory profiles) and by gas chromatography/mass spectrometry. The sensory profile of the concentrate was shown as slightly different from the unprocessed mussel cooking juice one. Nevertheless, the concentration process preserved the native characteristic aroma of the cooked mussel, of interest to human or pet food industries.     

反渗透浓缩籽瓜汁的实验研究

采用反渗透技术对籽瓜汁进行浓缩,分别研究了膜通量、压力、料液温度、籽瓜汁浓度等参数之间的关系,结果表明：反渗透膜对籽瓜汁有效成分的截留率接近100%,对无机盐截留率大于98%,籽瓜汁的最终浓缩浓度为20Brix;其它条件不变的情况下,膜通量与压力、料液温度成正比关系,与料液浓度成反比关系。     

Aroma of Canned Peach Halves Acidified with Clarified Lemon Juice

The aroma composition of canned peaches was studied during the 1st year of storage. Citric acid was substituted with 2 types of lemon juice: turbid and clarified. The volatiles were extracted using a distillation technique and quantified by gas chromatography‐mass spectrometry. A total of 35 aroma compounds were identified and quantified, with the major volatile components being lactones. The removal of monoterpenes, during the tangential flow filtration of the lemon juice, provided an acidifier with high scores in the sensory evaluation. In this study, a product perceived by the consumers as more “natural” was elaborated, and new industrial perspectives were opened for the lemon industry and agriculture.     

Changes in Volatile Components of Stored Tangerines and Other Specialty Citrus Fruits with Different Coatings

ABSTRACT: Shellac and wax-based citrus coatings were applied to Fallglo, Robinson, Sunburst, Dancy and Murcott tangerines, Nova and Orlando tangelos, and Temple oranges. Flavor volatiles were measured before and after storage. Concentrations of ethyl acetate, ethyl butyrate, isopentanol and 2-methyl-3-buten-2-ol increased markedly for fruit with shellac-based coatings, and were highly correlated with ethanol content, but at different ratios for the different varieties. The concentration increases were relatively less for fruit coated with the wax-based coatings, and suggest that high-gloss shellac and resin-based coatings are not appropriate for tangerines.     

A new integrated membrane process for the production of concentrated blood orange juice: Effect on bioactive compounds and antioxidant activity

The production of high quality concentrated blood orange juice according to a new integrated membrane process, alternative to thermal evaporation, was evaluated in terms of preservation of the total antioxidant activity and of the bioactive antioxidant components of the juice (ascorbic acid, anthocyanins, hydroxycinnamic acids, flavanones). The process was based on the initial clarification of freshly squeezed juice by ultrafiltration (UF); the clarified juice was successively concentrated by two consecutive processes: first reverse osmosis (RO), used as a pre-concentration technique (up to 25–30 °Bx), then osmotic distillation (OD), up to a final concentration of about 60 °Bx. During the concentration process of the liquid fractions, a slight decrease of total antioxidant activity (TAA) was observed (−15%), which was due to the partial degradation of ascorbic acid (ca. −15%) and anthocyanins (ca. −20%). Nevertheless, this degradation was lower than that observed with thermally concentrated juice: TAA, −26%; ascorbic acid, −30%, anthocyanins, −36%. The possibility to operate at room temperature allowed reduction in thermal damage and energy consumption. On the basis of these results, the integrated membrane process may be proposed as a valuable alternative to obtain high quality concentrated juice, as the final product still showed a very high antioxidant activity and a very high amount of natural bioactive components, showing a brilliant red colour and a pleasant aroma, characteristics that were significantly lost during traditional thermal evaporation.     

Production of volatile compounds by Rhizopus oligosporus during soybean and barley tempeh fermentation

Rhizopus oligosporus Saito can ferment soybeans or cereal grains to tempeh, a sliceable cake with improved nutritional properties. Volatiles produced by different R. oligosporus strains grown on malt extract agar (MEA), barley and soybean were investigated. The effect of co-cultivation with Lactobacillus plantarum on the production of volatiles was also studied. Volatile compounds were collected in situ by headspace diffusion and identified by GC-MS. The ten R. oligosporus strains that had different colony morphologies on MEA produced very similar volatile profiles, except for slight variations among the minor volatile compounds (e.g. sesquiterpenes). Likewise, practically no differences in volatile profiles were observed between three of the strains grown on soybeans. In contrast, the R. oligosporus volatile profile on soybean was different from that on barley from the same strain. Co-cultivation with L. plantarum did not influence volatile production by R. oligosporus. The dominant compounds produced on all three substrates were ethanol, acetone, ethyl acetate, 2-butanone, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-butanol. Acetaldehyde and 2-methyl-propanal were also produced on MEA and barley, while 2-pentanone, methyl acetate, 2-butanol and 3-methyl-3-buten-1-ol were observed on soybeans. Ethanol, 2-methyl-1-butanol and 3-methyl-1-butanol were the most abundant volatile compounds produced on MEA and barley, while 2-butanone was the dominant volatile metabolite on soybean. The mushroom odour compounds, 3-octanone and 1-octen-3-ol, were only detected from soybean and soybean tempeh.     

Hydroxyaldehyde products from hydroxyl radical reactions of Z-3-hexen-1-ol and 2-methyl-3-buten-2-ol quantified by SPME and API-MS

Hydroxyaldehyde products of the OH radical-initiated reactions (in the presence of NO) of two volatile vegetative emissions, Z-3-hexen-1-ol and 2-methyl-3-buten-2-ol, were examined to assess the qualitative and quantitative potential of two analysis techniques (1) sampling by Solid-Phase MicroExtraction (SPME) with on-fiber derivatization followed by gas chromatographic analyses and (2) in situ analysis by negative ion mode atmospheric pressure ionization mass spectrometry (API-MS). The compounds were chosen because reaction mechanisms predict hydroxyaldehyde products, and reliable coproduct yield data are available. The API-MS analyses showed product ion peaks attributed to the NO2- adducts of 3-hydroxypropanal and dihydroxynitrates from Z-3-hexen-1-ol, and a formation yield of 3-hydroxypropanal of 44% was derived. Product ion peaks attributed to NO2- adducts of glycolaldehyde [HOCH2CHO], 2-hydroxy-2-methylpropanal [(CH3)2C(OH)CHO], and dihydroxynitrates were observed by API-MS from 2-methyl-3-buten-2-ol, and a formation yield of 2-hydroxy-2-methylpropanal of 16% was obtained. In experiments with SPME sampling, the formation yields of hydroxycarbonyls measured as their oxime derivatives were as follows: from Z-3-hexen-1-ol, propanal, 56 +/- 8%; 3-hydroxypropanal, 101 +/- 24%; and from 2-methyl-3-buten-2-ol, 2-hydroxy-2-methylpropanal, 31 +/- 4%. Both the API-MS and SPME analyses provided product information, and hydroxycarbonyl yields from the SPME data are in reasonable agreement with previously measured formation yields of coproducts.     

2种浓缩方法对柠檬汁特性影响的比较

采用界面渐进冷冻浓缩法和真空蒸发法分别对柠檬汁进行界面渐进冷冻浓缩和真空蒸发浓缩。通过对 2种浓缩液处理前后柠檬汁香气成分含量的定性定量分析 ,以及柠檬汁色差、Vc含量、电导和 pH值的比较分析 ,证明了冷冻浓缩柠檬汁明显地比真空蒸发浓缩果汁能更好地保持柠檬汁的香气成分、Vc含量和原汁的香气协调性。     

Solid-liquid Extraction of Mushroom Solids and Concentration by Reverse Osmosis

Sliced cull mushrooms were extracted at 60°C, 75°C and 90°C using water, 10^-3M sodium metabisulfite or 10^-3M ascorbic acid solutions in a pilot scale counter-current slope diffuser. Extracts were centrifuged, ultrafiltered (UF) by a commercial great resistance, GR-51PP, 50,000 molecular weight cut-off membrane module, and then concentrated to 18-20% soluble solids (SS) by reverse osmosis (RO) using a high resistance, HR-95 membrane module. Primary mushroom volatiles including l-octen-3-ol and 3-octanone were evaluated in raw, extracted, and concentrated juices. The best temperature/solvent extraction system was 75°C in water with 98.2% soluble solids recovery. RO conducted at 10-20°C following the UF process gave an eight- to nine-fold concentration (from 1.8% SS. to 17.5% SS) with 85.1% solute recovery.     

Evaluation of hybrid pressure-driven and osmotically-driven membrane process for non-thermal production of apple juice concentrate

This study investigates the potential of hybrid membrane processes including microfiltration (MF), ultrafiltration (UF) and forward osmosis (FO) for non-thermal concentration of apple juice. The process performance and characteristics (physicochemical properties, nutritional and aroma components and microbiological quality) of apple juice were studied. The clarity of apple juice was significantly promoted as pore size of membrane reduced. MF and UF can also ensure microbiological safety in pre-treated apple juice. According to its efficiency of filtration as well as performance of simultaneous clarification and cold-sterilization, 0.22 μm MF membrane was identified as the optimal membrane for the pre-treatment. The pre-treated apple juice can be concentrated up to 65°Brix by subsequent single stage FO. FO retained nutritional and volatile compounds of apple juice while significant reductions were found in the juice concentrated by vacuum evaporation. Hybrid MF-FO can be a promising non-thermal technology to produce apple juice concentrate with high quality.     

Membrane separation technology for the reduction of alcoholic degree of a white model wine

The reduction of the alcoholic degree of a white model wine by means of membrane separation technology was studied in this work. Reverse osmosis and nanofiltration are the most promising processes for the production of wines with low alcohol content, because they can operate at low temperature and thereby preserve the aromatic profile of wine. Assuming that the rejection of the main wine compounds (i.e. acids, sugars and tannins) is very high, the aim of this research was to study the permeation of several characteristic aroma compounds in the white model wine. Permeation was conducted in batch retentate-recycling mode with two reverse osmosis and one nanofiltration membranes previously conditioned with a 12 ml/100 ml aqueous ethanol solution. Aroma compounds were identified by gas chromatography coupled to quadrupolar mass selective spectrometry. A mathematical model allowed calculation of the aroma compound concentrations in the retentate and permeate streams as a function of permeate volume and the concentration of solutes in the diluted final wine at 8 ml/100 ml ethanol concentration.     

Reverse Osmosis and Flavor Retention in Apple Juice Concentration

Plate-and-frame (PF) and spiral-wound (SW) membrane configurations were used to study influence of reverse osmosis (RO) on flavor compounds in apple juice permeate and retentate. Low temperature (20°C) and high pressure (50 bar) were most effective operating parameters for flavor recovery. Non-volatile flavor component RO losses were due to permeation. However, loss of volatile compounds through permeation was minor compared with equipment processing losses. Flavor compounds showed more rejection by polyamide than poly-ether-urea thin-film composite membranes. The SW configuration demonstrated greater flavor losses than did PF. Chemical structure of aldehydes and esters appeared to affect flavor compound retention. Volatile losses modified the flavor profile of RO concentrated apple juice.     

QUALITY CHANGES DURING STORAGE IN KOREAN CLEAR PEAR JUICES CONCENTRATED BY THREE METHODS

Pears of Shingo variety were coarsely ground, and subjected to heat treatment by HTST (high temperature short time) and pectinase treatment to produce a cloudy pear juice. The pear juice was then treated with Viscozyme, gelatin and bentonite, and filtered through an ultrafiltration membrane to produce a clear pear juice. The clear pear juice was concentrated to 3 to 5 fold by vacuum evaporation, freeze concentration, and reverse osmosis methods. The concentrates were diluted to 10° Brix and stored at 4C for 15 days. The single strength juice was evaluated for color, turbidity, heat stability, and sensory preference at 5 day intervals during storage. The pear juice concentrated by the three methods showed only small differences in quality. While the clear pear juice with added ascorbic acid had no quality changes at 4C after 15 days' storage, that without the addition of ascorbic acid resulted in some deterioration in browning, turbidity and heat stability after 10 days' storage. There were small, but significant flavor differences among clear pear juices concentrated by evaporation, freeze concentration and reverse osmosis.     

基于气相色谱-离子迁移谱技术分析不同包装条件对黄瓜风味的影响

为了研究在（13±2）℃下不同包装材料对黄瓜采后风味品质的影响,对厚度为0.03 mm的打孔聚乙烯包装袋、厚度为0.07 mm的打孔聚乙烯包装袋和无包装三种不同处理进行了评价。黄瓜中的挥发性有机化合物（volatile organic compounds,VOCs）通过使用气相色谱-离子迁移谱法（GC-IMS）进行分析,然后进行多变量分析。结果表明,黄瓜样品中共鉴定出60种挥发性物质,大致可分为2种烯类、14种醇类、13种醛类、13种酮类、8种酯类、5种酸类、3种醚类、1种吡嗪类和1种呋喃类。在多变量分析中,实验组之间实现了明显的分离。建议将由P<0.05且VIP得分>1的19种挥发性化合物组成的小组作为区分用不同包装材料处理的黄瓜的潜在标志,这19种挥发性化合物分别为丙酮、3-羟基-2-丁酮、3-戊酮、2,3-丁二酮、甲乙酮、甲基异丁酮、2-戊酮、2-己酮、异丁醛、丁醛、戊醛、3-甲基丁醛、1-丙醇、3-甲基-3-丁烯-1-醇、2-甲基-1-丁醇、异丁醇、1-戊醇、正丁醇和乙酸乙酯。在贮藏过程中,无包装黄瓜主要呈香的醛类减少更加明显,并产生一些酮类、酯类、醚类等挥发性代谢物,表明无包装中黄瓜特有的香气流失严重,而打孔自发气调包装中黄瓜主体呈香的醛类物质下降缓慢,且由于微生物滋生而产生的3-羟基-2-丁酮等物质增加也较少,总的说来,厚度为0.07 mm的打孔聚乙烯,建议作为相对有效的材料来保持黄瓜的味道质量。这些发现有望促进这些包装材料在黄瓜的大规模储存中的开发和应用。