Degradation kinetics of tomato juice quality parameters by ozonation

Tomato juice samples were ozonated with control variables of ozone concentration (1.6–7.8 %w/w) and treatment time (0–10 min). Effects of ozone processing variables on quality parameters of pH, ^oBrix, titratable acidity (TA), cloud value, non-enzymatic browning, colour values ( L *, a *, and b *) and ascorbic acid (AA) content were determined. No significant changes ( P  > 0.05) in pH, ^oBrix, TA, cloud value and Non enzymatic browning (NEB) ( P  ≤ 0.05) were found with ozonation. L *, a * and b * colour values were significantly affected by ozone concentration and treatment time. A significant reduction of AA (96 %) was observed at an ozone concentration of 7.8%w/w and a treatment time of 10 min. Results presented in this study indicate that visual colour and nutritional quality is significantly affected during ozone processing. Thus, the effects of ozonation on the nutritional properties of tomato juice should be considered by processors prior to its adoption as a preservation technique.     

Effect of Low Temperature Sonication on Orange Juice Quality Parameters using Response Surface Methodology

Freshly squeezed orange juice samples were sonicated at a constant frequency of 20 kHz for a range of processing temperatures (10–30 °C), amplitude levels (40–100%) and time (2–10 min) with pulse durations of 5 s on and 5 s off. Hunter colour values (L*, a* and b*), pH, ^oBrix, titratable acidity, cloud, non-enzymatic browning and ascorbic acid content were measured. Response surface methodology (RSM) based upon a three-factor, three-level Box–Behnken experimental design was used to determine the effect of independent variables. Under process conditions used in this study, no significant difference (p < 0.05) in pH, ^oBrix or titratable acidity was observed. Model predictions developed for Hunter colour values, cloud value, non-enzymatic browning and ascorbic acid content were closely correlated (R ² > 0.92) to experimental data. Box–Behnken design and RSM was demonstrated to be an effective technique to model the effect of sonication on juice quality while minimising the number of experiments required.     

Effect of freezing grape berries and heating must samples on extraction of components and composition parameters of red wine grape varieties

Juices from grape samples subjected to two storage methods (fresh and frozen) and two post-homogenisation treatments (21^oC and 71^oC) were examined for extraction of grape berry components and compared to a microvinified wine made from the same lot of fresh grapes. Cabernet Franc ( Vitis vinifera ) and Cynthiana ( Vitis aestivalis ) grapes were evaluated in 2003. Cabernet Franc, Cabernet Sauvignon ( Vitis vinifera ), Chambourcin (interspecific hybrid) and Cynthiana grapes were evaluated in 2004. Fresh grapes from each variety were sampled, analysed and prepared for microvinification. Frozen grapes of all varieties were thawed and analysed at the same time. For all varieties in both years, heating the must of fresh or frozen grapes increased the titratable acidity (11–58%), tartaric acid levels (12–110%), potassium content (15–62%), darkness (31–97%), red colour (54–1517%) and total red pigment values (36–1171%) of juice as compared to the juice from unheated must. For all varieties in 2004, heating the must from fresh or frozen grapes increased total phenolics (43–619%) of juice as compared to the juice from unheated must. Compared to fresh grape processing, freezing the grapes and then processing at 21^oC or 71^oC had varying results (increases and decreases) regarding the extraction of components in all varieties and both years but usually provided juice with composition most similar to that of the red wine produced by microvinification. Although the degree of extraction of individual components in the juice is influenced by selection of grape storage and must processing procedures, consistency of handling and procedure provided consistent results with low variability.     

Degradation of quality attributes of sweetened Julie and Ogbomoso mango juices during storage

Changes in the quality attributes of sweetened Julie and Ogbomoso mango juices were investigated. Sweetened mango juices were processed, bottled and stored at 25 °C for 12 weeks. The titratable acidity, pH, total solids, ash, soluble solids and ascorbic acid contents were evaluated immediately after processing and subsequently at 2-week intervals. The L*, a* and b* (HunterLab) parameters were determined to evaluate colour changes due to non-enzymatic browning.Generally, the quality attributes of the sweetened mango juices decreased during storage. The titratable acidity, pH, total solids, ash, soluble solids and ascorbic acid contents decreased during storage. After 12 weeks of storage, the percentage ascorbic acid loss of sweetened Julie and Ogbomoso mango juices was 16.25 and 16.67%, respectively. Browning index, chroma and b* values increased during storage. Colour changes in sweetened mango juices were mainly due to b* value and chroma.     

Effects of Dense Phase Carbon Dioxide Pasteurization on the Physical and Quality Attributes of a Red Grapefruit Juice

ABSTRACT:  Red grapefruit juice was treated with continuous dense phase carbon dioxide (DPCD) equipment to inactivate yeasts and molds and total aerobic microorganisms. A central composite design was used with pressure (13.8, 24.1, and 34.5 MPa) and residence time (5, 7, and 9 min) as variables at constant temperature (40 °C), and CO₂ level (5.7%) after experimentally measuring CO₂ solubility in the juice. Five log reduction for yeasts and molds and total aerobic microorganisms occurred at 34.5 MPa and 7 min of treatment. A storage study was performed on the fresh juice DPCD treated at these conditions. °Brix, pH, titratable acidity (TA), pectinesterase (PE) inactivation, cloud, color, hue tint and color density, total phenolics, antioxidant capacity, and ascorbic acid were measured after the treatment and during 6 wk storage at 4 °C. During storage, the DPCD-treated juice showed no growth of total aerobic microorganisms and yeasts and molds. Cloud increased (91%) while percent PE inactivation was partial (69.17%). No significant (α= 0.05) differences were detected between treated and untreated samples for °Brix, pH, and TA. Treated juice had higher lightness and redness and lower yellowness. No significant differences (α= 0.05) were detected for the hue tint values while the color density value was higher for the treated samples compared to the untreated. The treatment and the storage did not affect the total phenolic content of the juice. Slight differences were detected for the ascorbic acid content and the antioxidant capacity. The experimental results showed evidence that the treatment can maintain the physical and quality attributes of the juice, extending its shelf life and safety.     

Quality of Fresh-cut Apple Slices as Affected by Low-dose Ionizing Radiation and Calcium Ascorbate Treatment

ABSTRACT: Although ionizing radiation effectively inactivates food-borne bacterial pathogens in fresh-cut fruits and vegetables, it may adversely affect product quality. In this study, the effects of calcium ascorbate (CaA) and ionizing radiation on quality of 'Gala' apple slices under modified atmosphere packaging were investigated. 'Gala' apple slices, treated with water or 7% CaA followed by either nonirradiation (0 kGy) or irradiation at 0.5 and 1.0 kGy, were stored at 10°C for up to 3 wk. The titratable acidity, pH, firmness, ascorbic acid content, color, and microflora population were measured weekly throughout storage. Irradiation did not affect titratable acidity and pH of sliced apples. Fruit slices softened during irradiation and storage, but this decrease in firmness during storage was reduced by the CaA treatment. Although the ascorbic acid content of apple slices treated with CaA decreased rapidly during storage, the ascorbic acid content was always higher in those treated samples than in the apple slices treated with water. Irradiation decreased both L * and hue values of apple slices. Hue values decreased during the entire storage period while L * increased during the 1st wk of storage, then decreased between 1 to 3 wk of storage. CaA increased L * and hue values of apple slices, suggesting CaA reduced browning, even in irradiated samples. The microflora population of apples slices was not affected by CaA, and CaA treatment did not alter the reduction in microflora by irradiation. The combination of CaA and irradiation enhanced microbial food safety while maintaining quality of fresh-cut apple slices.     

蟠桃品种用于加工鲜榨汁的适宜性评价

为研究不同蟠桃品种的鲜榨汁加工适宜性,本实验对北京平谷地区的7 个蟠桃品种的理化与营养指标（pH值、总酚含量、抗坏血酸含量、蛋白质含量、可滴定酸含量、可溶性固形物含量（soluble solids content,SSC）、固酸比、果胶含量）和加工品质指标（单果质量、L*、a*、b*值、褐变度、出汁率、黏度）进行了测定,并从色泽、气味和风味三方面进行感官评价。通过相关性分析、主成分分析和聚类分析法筛选出了SSC、出汁率、果胶含量、a*值和蛋白质含量5 个核心品质评价指标。通过层次分析法得出：SSC和出汁率的权重值为0.32,果胶的权重值为0.18,a*值和蛋白质的权重值分别为0.11和0.07。对7 个蟠桃品种的鲜榨汁品质综合评价表明：瑞蟠21的鲜榨汁品质最好,其次为瑞蟠20、瑞蟠4和瑞蟠19,而巨蟠、瑞蟠2和瑞蟠3的鲜榨汁品质较差。     

石榴-胡萝卜复合饮料理化性质、抗氧化活性及其货架期的研究

以石榴、胡萝卜为原料,按质量比1∶3、1∶1、3∶1混合配制石榴-胡萝卜汁复合饮料,研究常温(25±1)℃下60 d的储存期内其物理化学性质(pH值、可溶性固形物、总酸度)、抗坏血酸、总酚以及抗氧化活性的变化,并对复合汁进行感官评价。结果表明,3个样品的pH值分别为4.04、3.92和3.38,可溶性固形物分别为5.02%、6.14%和8.13%,总酸度分别为0.74、0.74 g/100 mL和0.77 g/100 mL,在60 d的货架期pH值有所降低,可溶固形物含量没有明显的变化,而总酸度有所增加。抗坏血酸含量以质量比为1∶3的混合汁占优,总酚含量、DPPH自由基清除率以质量比为3∶1的混合汁占优,3项指标在货架周期内呈总体下降趋势。质量比为1∶1的石榴-胡萝卜复合汁感官评价得分最高。     

Effects of sucrose polyester coating on fruit quality of apricots (Prunus armenaica (L))

Mature apricots were coated with different concentrations of a mixture containing sucrose polyesters (Semperfresh(tm) fruit coating) to determine the effect of that coating on shelf-life, post-storage life and quality of apricots. Respiration rates, weight loss, colour change, variations in soluble solids, ascorbic acid content, titratable acidity and pH of apricots were effectively reduced by both the 10 g litre^?1 and 15 g litre^?1 concentrations during ambient storage. After 10 days of cold storage both concentrations caused firmer fruit, higher pH, titratable acidity, soluble solids and ascorbic acid.     

A comparison of the functional characteristics of wheat stored as grain with wheat stored in spike form

In this study, wheat grain and wheat spike with 12%, 14% and 16% moisture content were stored at 10, 20 and 30 °C for 0, 3, 6 and 9 months. After storage, wheat samples were investigated for hectolitre weight, gluten content, Zeleny sedimentation volume, enzyme activity, acidity, phytic acid and L colour value. Storage of wheat at different storage forms (spike and grain) and storage conditions showed considerable changes in grain quality. In general, the storage period of 3 months positively affected wheat quality. However, hectolitre weight, gluten, Zeleny sedimentation, enzyme activity, acidity and colour of wheat got worse at storage periods beyond 3 months. Hectolitre weight, wet and dry gluten, Zeleny sedimentation, phytic acid content and L Colour value of wheat stored in both spike and grain form significantly decreased during storage. However, the increase in grain moisture content, storage time and temperature resulted in significant increase in total titratable acidity and falling number values of wheat. Falling Number and phytic acid values of wheat stored in spike form were generally lower than wheat stored in grain form. Storage in spike form had a positive effect on especially wet gluten content of wheat stored at non-optimal storage conditions such as high grain moisture content and high temperature. Wet gluten of wheat stored in spike form was higher than that of wheat stored grain form after storage at 30 °C for 6 and 9 months. Wheat stored in spike form is more resistant than wheat stored in grain form against adverse storage conditions such as high moisture content and temperature and longer storage time.     

Maintaining the quality of sugarcane juice with blanching and ascorbic acid

The physicochemical changes in fresh sugarcane juice stored at 10 °C were studied by determining juice yield, color, reducing sugar, titratable acidity, viscosity, pH, polyphenol oxidase (PPO), sucrose neutral invertase (SNI) and total microbial count. Results showed that blanching of stems before squeezing effectively prevented degreening and/or browning, and reduced activities of PPO and SNI in fresh sugarcane juice. Added ascorbic acid delayed the increase of reducing sugar, titratable acidity, viscosity and total microbial count, and also prevented degreening and/or browning with reduced PPO and SNI activities in fresh sugarcane juice during storage. Addition of 0.1% ascorbic acid seemed to be more effective than blanching of sugarcane stems, and was able to maintain the quality of fresh sugarcane juice for up to 5 days at 10 °C. Deterioration of fresh sugarcane juice was demonstrated as a rapid increase of titratable acidity and viscosity with a obvious browning.     

CONTROLLED ATMOSPHERE STORAGE AND EDIBLE COATING EFFECTS ON STORAGE LIFE AND QUALITY OF TOMATOES

Tomatoes at pink stage maturities were coated with Semperfresh^TM edible fruit coating which is composed of sucrose esters of fatty acids, sodium carboxymethyl cellulose and mono-diglycerides of fatty acids. One group of coated and uncoated tomatoes were stored at 23 × 2C under air atmosphere, another group was stored at 12C under air atmosphere and third group was stored at 12C, 93–95% RH in a controlled atmosphere (CA) containing 3% CO₂, 3% O₂ and 94% N₂. Samples of tomatoes were analyzed for firmness, weight loss, titratable acidity, pH, soluble solids, sugars, ascorbic acid and lycopene to examine changes in quality during storage. Semperfresh^TM edible fruit coating was found to be significantly effective at both storage temperatures (23 × 2C and 12C) in air to delay changes in firmness, titratable acidity, pH, soluble solids, sugars, ascorbic acid and lycopene. Semperfresh^TM fruit coating reduced fruit weight loss as compared to fruit without coating but the difference between coated and uncoated tomatoes was not significant. Shelf-life of pink tomatoes was increased 3 days at 23 × 2C and 6 days at 12C in air by coating. CA storage delayed compositional changes in tomatoes significantly as compared to air storage of coated and uncoated tomatoes. CA storage also had a significant potential for reducing weight loss and microbial spoilage. Tomatoes were stored 40 days in CA. Coated and uncoated tomatoes exhibited the same results in CA.     

Colour degradation and quality parameters of sonicated orange juice using response surface methodology

Freshly squeezed orange juice was subjected to sonication at amplitude levels ranging from 40 to 100% at a constant frequency of 20 kHz for different times (2-10 min) and pulse durations of 5 s on and 5 s off. Hunter colour values (L^∗, a^∗ and b^∗), pH, °Brix, titratable acidity, cloud value and browning index were measured. Response surface methodology (RSM) based on two factor five level central composite design was applied to determine the effect of amplitude level and sonication time on juice quality parameters. There was no significant difference (p < 0.05) on pH, °Brix and titratable acidity. The model predictions for critical quality parameters of Hunter colour values (L^∗, a^∗ and b^∗), cloud value and browning index were closely correlated to the experimental results obtained. RSM was demonstrated to be an effective technique to model the effect of sonication on juice quality while minimising the number of experiments required.     

COLOR AND VITAMIN C CONTENT IN MANDARIN ORANGE JUICE AS AFFECTED BY PACKAGING MATERIAL AND STORAGE TEMPERATURE

Mandarin orange (Citrus reticulata) juice was packed in two different non-transparent cartons made of polyethylene, cardboard and (1) aluminum foil (Tetrapak ^® ) or (2) ethylene vinyl alcohol copolymers (Pure-pak ^® ) and was stored at 4C or room temperature (25  ±  3C). During the shelf life of these juices (35 days), changes in the headspace gas composition, vitamin C and CIEL*a*b* color coordinates were evaluated. In addition, a consumer panel evaluated the sensory color of the juices. Mandarin orange juices darkened and ascorbic acid content decreased with storage time. Type of carton and storage temperature played a predominant role in determining the final juice quality, with Tetrapak ^® carton providing the juice with the best quality (intense orange color and high vitamin C content and consumer preference) throughout their shelf life.

PRACTICAL APPLICATIONS

This study was a clear example of how research can help real food companies in selecting the right materials for their production lines. In this particular case, the results presented show how Tetrapak^® packaging led to a final mandarin orange juice of higher quality compared to Pure-pak^® packaging. Therefore, citrus processing companies have some scientific data comparing the behavior of these two types of non-transparent cartons. Besides, the companies manufacturing these cartons also have some information about their materials and can use it to improve them.     

Postharvest application of 1-Methylcyclopropene modulates fruit ripening, storage life and quality of 'Tegan Blue' Japanese plum kept in ambient and cold storage

The role of postharvest application of 1-Methylcyclopropene (1-MCP) in modulating 'Tegan Blue' Japanese plum fruit ripening and quality under ambient and cold storage conditions was investigated. 1-MCP-treated fruit (0, 0.5, 1.0 and 2.0 μL L⁻¹) were allowed to ripen at ambient temperature in Experiment 1, while in the second experiment the fruit were kept in cold storage (0, 3 and 6 weeks) before ripening. In both experiments, 1-MCP treatment significantly delayed (2–8 days), suppressed (30–70%) the climacteric ethylene production, maintained higher fruit firmness (34–60%), titratable acidity, L* , chroma, hue angle of fruit skin and pulp, and reduced concentrations of soluble solids, ascorbic acid, total carotenoids and total anti-oxidants as compared to the control. 1-MCP (1.0 μL L⁻¹) treatment suppresses and delays the climacteric ethylene production with acceptable fruit quality during ripening at ambient temperature and is effective in extending the storage life up to 6 weeks with minimal loss of plum fruit quality.     

RELATIONSHIPS OF COLOR, VISCOSITY, ORGANIC ACID PROFILES AND ASCORBIC ACID CONTENT TO ADDITION OF ORGANIC ACIDS AND SALT IN TOMATO JUICE

Malate and citrate acidified juices produced statistically similar results for pH and titratable acidity (TA), but these acidified juices were significantly different from nonacidified juice when comparing pH and TA. During storage time, the pattern of the pH and TA curves, regardless of acidification, were similar. Salted juice exhibited a significantly higher ascorbic acid content and greater viscosity than did the unsalted juice during storage. The organic acids citric, lactic, malic, and pyrocarboxylic increased immediately after heat processing for commercial sterility, while the presence of salt in this juice lowered these same organic acids. There was minimal correlation of the organic acids or the summation of the acids equivalents of all the organic acids to the titratable acidity or pH of the juices. Juices acidified with malate or citrate did not consistently display an increased level of that specific acid after processing and storage.     

Effect of Thermal Processing and Carbon Dioxide-assisted High-pressure Processing on Pectinmethylesterase and Chemical Changes in Orange Juice

ABSTRACT: The effects of high-pressure processing (HPP), CO₂-assisted high-pressure processing (HPP + CO₂), and thermal processing on the chemical and physical properties of single-strength Valencia orange juice were evaluated over 4 mo of storage at 4 and 30 °C. The HPP + CO₂ juice had the greatest cloud stability and highest ascorbic acid retention. Volatile compound losses were lowest in the HPP juice and lower in the HPP + CO₂ juice compared to the thermally processed juice (p < 0.05). HPP + CO₂ produced a cloud-stable orange juice with more ascorbic acid and flavor volatiles than thermally processed juice (p < 0.05).     

Physicochemical parameters,bioactive compounds and microbial quality of sonicated pear juice

This study was carried out to investigate the effect of sonication on physicochemical parameters and microorganisms of pear juice. Ultrasound processing of fresh pear juice was done at fixed amplitude [70% (500 W) and frequency (25 kHz) for 0, 15, 30, 45 and 60 min at 25 °C. Total soluble solids, pH, titratable acidity and Ca and Mn remained stable, while the cloud value, ascorbic acid, total phenols, total flavonoids, total antioxidant capacity, sugar contents and Na, K, Fe and Mg showed a significant increase. Decreases in microbial population and P and Cu were also observed. It may be inferred that ultrasound processing for 60 min exhibited optimum results in terms of physicochemical and microbial quality.     

Effect of sonication on colour,ascorbic acid and yeast inactivation in tomato juice

Power ultrasound is recognised as a potential non-thermal technique to inactivate micro-organisms pertinent to fruit juices. In this study tomato juice was sonicated at different amplitude levels (24.4–61.0 μm) at a constant frequency of 20 kHz for treatment times (2–10 min) and pulse durations of 5 s on and 5 s off. Hunter colour values (L∗, a∗ and b∗), pH, °Brix, titratable acidity, ascorbic acid and yeast inactivation were measured. No significant differences (p < 0.05) in pH, °Brix or titratable acidity were observed. Regression modelling was used to investigate the main effects of amplitude level and treatment time. Prediction models were found to be significant (p < 0.05) with low standard errors and high coefficients of determination (R²). Model predictions for critical quality parameters of Hunter colour values (L∗, a∗ and b∗), ascorbic acid and yeast inactivation were closely correlated with the experimental results obtained.     

Guava puree with reduced stone cell content: preparation and characteristics of concentrates and nectars

A decanter centrifuge was used to decrease the content of stone cells in guava puree before evaporation. Concentration factors between 3.3- and 4.3-fold were achieved. Thirty-seven per cent of the stone cells could be removed in a small decanter, whereas virtually all sclereids are removed on an industrial scale. Small significant increases in moisture contents, total soluble solids and titratable acidity and decreases in pectin fractions and ascorbic acid contents (average 38%) occurred during processing; guava colour became darker, redder and less yellow. The apparent viscosity of the puree decreased after centrifugation and increased again during evaporation. Nectars prepared from puree with reduced stone cell content were the most stable. Concentration of puree reduced cloud stability of nectars by up to 34% after 35 days storage, but homogenization improved the stability. Panel members only found significant differences in the colour of nectars prepared from the three concentrates.