Single-strength Juice Research Articles

Aroma profiles of pineapple fruit (Ananas comosus [L.] Merr.) and pineapple products

The flavour profile of juices made from fresh-cut pineapple fruits (n=19; Costa Rica, Ghana, Honduras, Ivory Coast, Philippines, La Réunion, South Africa, Thailand) was studied in comparison to that of commercial water phases/recovery aromas (n=16), juice concentrates (n=10) as well as commercially available juices (n=17). In addition, pineapple jams (n=6; market samples) were investigated. HRGC-MS analysis of juices made from fresh-cut fruit revealed the known prevalence of esters, with methyl 2-methylbutanoate, methyl 3-(methylthio)-propanoate, methyl butanoate, methyl hexanoate, ethyl hexanoate and ethyl 3-(methylthio)-propanoate, as well as 2,5-dimethyl-4-methoxy-3(2H)-furanone (mesifurane) and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (furaneol) as major constituents. A corresponding flavour profile was rarely found in water phases/recovery aromas under study. In most cases, the characteristic methyl esters and hydroxy or acetoxy esters were lacking completely or appeared only in minor amounts in these products. Whereas a few of the commercial single strength juices revealed fruit-related flavour profiles, juices produced from concentrates mostly exhibited a flavour composition similar to that of concentrates, i.e. they were predominantly determined by their contents of furaneol and did not show the fruit-related ester distribution. Similarly, the jams under study were poor in typical pineapple constituents.

PINEAPPLE JUICE CONCENTRATED BY OSMOTIC EVAPORATION1

AbstractPasteurized pineapple juice was concentrated by osmotic evaporation to produce a 51 d̀Brix concentrate that was reconstituted to single strength juice for evaluation. Headspace gas chromatography (HSGC) showed that the concentrate retained an average of 62% of the volatile components present in the initial juice. A sensory panel preferred initial juice over reconstituted concentrate, and noted a decrease in desirable flavor top notes as well as development of some processed flavor in the concentrate. Similar HSGC analysis of four other commercial juice samples showed a wide range of quantitative values for volatile components, with the initial juice being similar to the weakest of these commercial juices. Analysis of concentrated juice extracts permitted identification of additional less‐volatile components not monitored directly by HSGC of the juice. Relatively low levels of these components were also present in the initial juice. Although this nonthermally produced concentrate retains more volatile components than when traditional thermal processing methods are used, addition of aqueous aroma to the concentrate may be required for satisfactory flavor.

Phenolic Composition of Authentic Pineapple Juice

ABSTRACT: The phenolic composition of authentic pineapple juice concentrate was analyzed by HPLC. Nine major peaks accounting for 70% of total peak area were characterized and their concentrations measured in 54 commercial samples. Means and standard deviations were as follows (mg/100 mL single‐strength juice, normalized to 12.8 °Brix): tyrosine, 3.6(1.4); serotonin, 1.8(0.8); dimethylhydroxylfuranone, 1.4(0.7); dimethylhydroxylfuranone β‐glucoside, 6.2(3.0); tryptophan, 2.2(0.9); S‐sinapyl‐L‐cysteine, 1.1(0.6); N‐γ‐L‐glutamyl‐S‐sinapyl‐L‐cysteine, 2.3(1.1); S‐sinapyl glutathione, 5.4(1.4); and a p‐coumaric acid‐like phenolic compound (calculated as p‐coumaric acid), 0.5(0.4). This information will be useful for evaluation of authenticity and quality.

Free volatile components of passion fruit puree obtained by flash vacuum-expansion.

Purple passion fruits were processed by the flash vacuum-expansion process. Volatile components were analyzed in purees from steam-heated fruits, steam-heated then vacuum-expanded fruits and their aromatic liquors, and fruit rind, in comparison with a reference single-strength juice. After steam heating, the puree was enriched in esters arising from the rind. Steam-heated then vacuum-expanded fruits yielded a puree impoverished in volatiles due to evaporation of approximately 10% of water. These volatile compounds were mostly recovered in aromatic liquors.

Long-term survey of patulin in apple juice concentrates produced in Turkey

A liquid chromatographi c method described by us elsewhere was evaluated for a long-term survey of patulin in apple juice concentrates. Patulin was separated on a reversed phase C18 LC column with water-acetonitrile (99:1) as the mobile phase and quantitated with a photodiode array (PDA) detector. Relatively low amounts of patulin (< 5 μg/l for single strength juice at 11.2° 8Bx) were detected in apple juice concentrates and confirmed by PDA detector, comparing the corresponding UV spectra with that of patulin standard. Four hundred and eighty two apple juice concentrates produced through 1996-99 were analysed for their patulin contents. Year-to-year variations in patulin levels of apple juice concentrates were found out to be statistically significant. Patulin contamination levels of apple juice concentrates tended to decrease through the years and averaged 63, 43, 19 and 31 μg/l in 1996, 1997, 1998 and 1999, respectively. Percentages of concentrates exceeding the maximum permitted concentration of 50 μg/ l were 52%, 34%, 8% and 8% for 1996, 1997, 1998 and 1999, respectively.

Reduction of azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl residues in processed apples.

McIntosh, Red Delicious, and Golden Delicious from two years of experimental spray programs using azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl were processed into frozen apple slices, applesauce, single-strength juice, and juice concentrate. Residue levels were expressed as micrograms per 150 g of apple or the equivalent amount of apple product to calculate the percentage change in these pesticides brought about by processing. Producing single-strength apple juice reduced azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl residues by 97.6, 100, 97.8, and 78.1%, respectively. Production of applesauce reduced all four compounds by >/=95%. Azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl residues were reduced in apple slices by 94.1, 85.7, 98.6, and 94.7%, respectively. Processing is shown to be very effective in reducing the levels of these pesticides.

Comparison of Headspace GC and Electronic Sensor Techniques for Classification of Processed Orange Juices

Three types of commercial orange juice samples (pasteurized not from concentrate; frozen concentrate and single strength juice reconstituted from concentrate) were classified by discriminant analysis using quantities of 25 volatile juice constituents determined by headspace gas chromatography (HSGC). An electronic sensor instrument was also used to evaluate and classify the same juice samples, and the results were compared to those obtained by HSGC. Two sets of samples were classified by HSGC analysis into the three juice types. The electronic sensor instrument classified the first set into three types, but was less successful in classification of the second larger set of samples. The two analytical techniques were complimentary since they afforded somewhat different separation patterns.

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

ABSTRACTPears 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.

Differences in Amino Acid Composition in Commercial Orange Juices

The amino acid composition of two sets of commercial orange juice was determined, and the mean value and range of values for each amino acid were tabulated. Single-strength juices from concentrates showed lower content of amino acids than straight-processed juices. Statistical comparison by ANOVA revealed statistical significance (p ≤ 0.001) for aspartic, arginine, asparagine, glutamine, serine, threonine, and isoleucine, between straight-processed orange juices, and those single-strength juices from concentrates. The combination of glutamine, asparagine, and alanine allowed a 100% correct classification. Keywords: Commercial orange juices; amino acids; discriminant analysis

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

ABSTRACTSupercritical 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.

Heat Resistance of Escherichia coli O157:H7 in Apple Juice

The objective was to determine the effect of cider composition on the heat resistance of Escherichia coli O157:H7. The average D52 value in a model Empire apple juice was 18 min with a z value of 4.8°C. Increasing the Brix from 11.8 to 16.5° had no effect on thermal resistance, while increasing L-malic acid from 0.2 to 0.8%, or reducing the pH from 4.4 to 3.6 sensitized the cells to heat. The greatest effect on heat resistance was afforded by the preservatives benzoic and sorbic acids: D50 values in ciders containing 1,000 mg/l were 5.2 min in the presence of sorbic acid and only 0.64 min in the presence of benzoic acid. Commercial apple juice concentrates yielded lower numbers of survivors than single-strength juices even though their higher sugar concentrations of about 46° Brix increased heat resistance.

Oligosaccharide Generation in Acidic Sugar Media

Abstract Oligosaccharides were shown to be present in beet medium invert sugar, but the origin of these molecules has remained obscure. The present study reveals that oligosaccharides are not a contaminant of purified beet sucrose. They appear during sucrose hydrolysis but are not specific to inversion. Sugars in a solution containing hydrogen ions generate oligosaccharides whose nature and proportion is determined by the original sugar composition. Because the sugar composition changes constantly during the course of sucrose inversion, the oligosaccharide pattern of a medium invert sugar is determined by the sugar distribution existing when the hydrolysis is stopped. As a consequence, the oligomer composition of a solution does not depend on the botanical origin of the sugar. Nearly identical oligosaccharide profiles were obtained from beet, cane, and citrus saccharides inverted in the laboratory or obtained from an industrial source. The amount of oligomers generated by an acidic solution increases exponentially with the sugar concentration. In diluted medium invert sugar solutions or in single-strength juices, the equilibrium between monomers and oligomers shifts toward depolymerization and eventually leaves only monosaccharides. In concentrated solutions of sugars or citrus juices, on the other hand, the process is directed toward oligomerization. These reactions occur slowly at room temperature but are greatly sped up by temperature. Therefore, results from the quantitation of oligosaccharides should be carefully interpreted if an accurate monitoring of medium invert sugar adulteration is to be performed. The nature of the product (single-strength or concentrate) and the types of treatment to which the product was submitted must be considered. Although monitoring of oligosaccharides provides a rapid method for the detection of added invert sugar, some results may need to be corroborated by methods such as isotopic analysis.

Nutritive composition of Al-Nokel grape fragments and the potentiality of making evaporator-concentrate

A study was designed to produce evaporator-concentrated juice from Al-Nokel grapes and to contrast the proximate, physical and elemental composition of the fresh fruits (edible portion), single strength juice and the concentrate. Also, changes during storage in physicochemical (reducing sugars, sucrose, ascorbic acid and acidity), microbial and sensory characteristics were studied to determine the effect of storage time and storage temperature on the quality. The Al-Nokel grape cultivar is grown on a commercial level in the Al-Nokel area in Al-Madina Al-Monawara City, the South-Eastern region of Saudi Arabia. Proximate analysis indicated that the protein, lipid and ash contents of the edible portion of Al-Nokel grapes found in this study were approximately in agreement with the literature values (FAO, (1982) Food Composition Tables for the Near East. FAO, Rome; Paul & Southgate, (1978) The Composition of Foods. Elsevier/North-Hall, New York) but the total sugar content was higher than those reported in the literature and by Wall & Merrill (1975) Composition of Food, Agricultural Handbook no. 8. Consumer and Food Economics Institutes. Agricultural Research Service, US Department of Agriculture, Washington, DC. The edible portion of the fruit was found to be rich in potassium and magnesium while the fresh extracted juice was a fair source of potassium, magnesium and iron. The decrease in sucrose and ascorbic acid and the increase in reducing sugars were linearly related to the storage time. The increase in the reducing sugars was due to the hydrolysis of the sucrose under these conditions. The results of sensory evaluation indicated that panellists were not able to detect any significant changes in the quality attributes after 2 months of storage at various temperatures. However, after 6 months of storage there was a significant difference ( p < 0.05) in colour, flavour and overall acceptability between samples stored at 25°C and those stored at 1 and 5°C. Microbial analysis revealed that the concentrates stored at the three various temperatures were microbially stable through the storage period, and showed the absence of aerobic plate counts, coliforms, sporeformers and yearsts and moulds.

極早生ウンシュウの果汁成分特にリモノイド含量の系統間差異

The physical and chemical properties of fruits used as raw materials for juice processing were examined among 12 strains in 6 classes of very early ripening mutants of Wase satsuma mandarin (Citrus unshiu Marc. var. praecox Tanaka) with special reference to the limonoid compounds.All the strains used in these experiments completely fulfilled the criteria of the Japanese Agricultural Standard (JAS) for single-strength juice. On the basis of these criteria, the sugar, citric acid, ascorbic acid (vitamin C), amino-nitrogen and ash contents in the very early ripening mutants were suitable for juice processing.However, the contents of limonoid compounds of these strains were much higher than those of Wase and Common satsuma mandarin at the usual harvest time. Such high contents may cause the so called delayed bitterness in their juice products after processing with an In-Line juice extractor. Therefore, to alleviate this shortcoming, it is suggested that the fruits should be harvested at the full ripening stage.Although the mutants were classified into 6 maturation types based on the variations of acid contents and coloring time of the fruit, the maturation time could not be estimated on the basis of the contents of limonoid compounds.

Low pH Inactivation of Pectinesterase in Single Strength Orange Juice

ABSTRACTFrozen orange juice concentrate (63.8° Brix) was reconstituted with water to single strength juice and supplemented with a commercial citrus pectinesterase (PE) to give an activity of 1.5 PE units/mL juice. Reconstituted juice and freshly squeezed single strength orange juice were treated with a cation exchange resin. Resin treatment decreased the pH of the juice from 3.75 to 2.0 and completely inactivated PE. PE was also inactivated following acidification of the juice to pH 2.0 with concentrated hydrochloric acid. Very little cloud loss occurred in refrigerated (4°C) juice at pH 2.0 for approximately 12 wk; however, a loss (&gt; 95%) of ascorbic acid resulted. Only microorganisms died‐off rapidly (&gt; 99.9%) in juices adjusted to pH 2.0 using ion exchange resin, but not in juices lowered to pH 2.0 with HCl.

A Shelflife Evaluation of an Oriented Polyethylene Terephthalate Package for Use with Hot Filled Apple Juice

ABSTRACTA year long storage study was undertaken to evaluate an oriented polyethylene terephthalate (OPET) container for use with hot filled juice. Freshly made juice as well as single strength juice reconstituted from commercial apple juice concentrate were evaluated. The results indicated that the oxidation of the juice by way of oxygen permeation through the OPET barrier was slow enough to allow for a satisfactory shelf life as compared to glass‐packaged samples over a 6–9 month period. Surface‐to‐volume effects did not become significant until late in the study. Difference and preference tests were used to establish shelflife comparison between OPET packages and glass‐packaged products.

Freeze Concentration of Pineapple Juice

ABSTRACTJuice, extracted from fresh Costa Rican pineapples using a commercial extractor, was adjusted by finishing and centrifugation to two pulp levels, 12% and 2% by volume. Physical, chemical and sensory differences were measured in heat stabilized single strength juices, evaporator concentrated, and freeze‐concentrated juices. Results indicated no significant differences between samples for Brix, % acid, total hexose, vitamin C, browning index, color, viscosity. Pulp content was lower in both freeze‐ and evaporator‐concentrated samples. Significant (P &lt; 0.01) flavor differences were detected between freeze‐and evaporator‐concentrated juices. Juices were ranked according to highest degree of fresh fruit taste as follows: (1) high pulp single strength, (2) freeze concentrate high pulp, and (3) evaporator concentrate high pulp. Flavor of reconstituted freeze‐concentrated juice was comparable to single strength juice and preferable to evaporator concentrate.

ENERGY CONSUMPTION IN A CONCENTRATED ORANGE JUICE PLANT

ABSTRACTThe consumption of electricity and thermal energy for frozen concentrated orange juice (FCOJ) and citrus pulp pellets (CPP) was determined in a plant. Thermal energy accounted for 90% of the total energy consumption in the plant and its consumption for CPP exceeded that for FCOJ. The kilocalories of thermal energy per kg of water evaporated (KKWE) in the evaporators increased as the feed rate of single strength juice was decreased. At the design evaporation capacity, the steam efficiency of two tubular evaporators and two plate evaporators was found to be 0.85N and 0.82N, respectively; N being the number of effects of the evaporator. Fouling of the waste heat evaporator was a major reason for the high energy consumption in the CPP unit.

Statistical Evaluation of Data for Detecting Adulteration of California Navel Orange Juice

ABSTRACTCompositional data from California early‐, mid‐, and late‐season navel orange juice, concentrate and two‐stage pulpwash were analyzed by various statistical techniques (ratios, regression, chi‐square, Linear combination, and discriminant analysis) for detecting adulteration. These techniques were evaluated according to applicability for detecting three types of adulteration: (1) addition of sugar and/or citric acid, (2) addition of excess or unauthorized pulpwash, and (3) addition of other constituents intended to mask the dilution. Most parameters were significantly affected by time of harvest following commercial maturity. Two‐stage pulpwash showed small but significant differences from corresponding single strength juice. Product differences were of about the same magnitude as the differences due to harvest date.

Storage behaviour of freeze dried fruit juice powders

SummaryThe stability of nutrients and chemical changes in freeze dehydrated juice powders based on a few of the locally available fruits, during storage at ambient temperature (24‐28°C) and also at 37°C were studied. Single strength juice and ready‐to‐serve beverages, fortified with sugar to raise the brix to 15 and 20 respectively prepared from these fruits were taken for freeze drying and further storage studies. the sugar fortified juice powders of 15° and 20° brix had a longer shelf life compared to their single strength counterpart. of the two varieties of mango studied, Badami had a longer shelf life compared to Raspuri. Comparing mosambi, pineapple and mango, mosambi retained maximum amount of ascorbic acid at both the temperatures.