Thermal processing,storage conditions,and the composition and physical properties of orange juice

Mexican orange juice bottled without pasteurization and frozen, or orange juice that was pasteurized, bottled, and frozen or orange juice pasteurized and stored at 1°C in plastic bins was sampled monthly for eight months. Juice density, cloud, and fructose levels were all significantly (P<0.05) affected by the method of processing. Pasteurization reduced orange juice ascorbic acid concentrations. The concentrations of acetaldehyde and ethyl acetate were highest in unpasteurized juice. α-pinene, β-myrcene, limonene, α-terpineol, 1-hexanol, 3-hexen-1-ol and sabinene concentrations were highest in the unpasteurized juice.     

The effect of storage on the antioxidant activity of reconstituted orange juice which had been pasteurized by high pressure or heat

The effect of storage on the antioxidant activity of pasteurized reconstituted orange juice was studied. Either heat or high pressure was used for pasteurization and total antioxidant activity and ascorbic acid loss were measured during storage at different temperatures (0, 5, 10, 15 °C). The total antioxidant activity of orange juice, calculated as the sum of the activities of different antioxidant compounds, decreased during storage. This was mainly because of loss of ascorbic acid. However, rates of degradation of ascorbic acid were lower for orange juice treated with high pressure and this led to a better retention of its antioxidant activity when compared with juice pasteurized in a conventional way.     

Novel approaches to reduce brown pigment formation and color changes in thermal pasteurized tomato juice

The effects of two heat processes mild-temperature pasteurization (MTP: 75 °C, 23 s) and high-temperature pasteurization (HTP: 92 °C, 5 s) on undesirable brown color development and some quality attributes (pH, soluble solids content, and color parameters) of pasteurized tomato juice were evaluated and compared during 94 days of storage at 5 °C. Although both heat treatments combined with refrigeration prevented microbial growth for 64 days, the shelf life regarding acceptable microbial load of HTP-treated sample was higher than 94 days. Both processes produced lesser brown color formation in tomato juices than the commonly adopted thermal treatments although the MTP processing provides better color preservation than the HTP one. No effect of heat treatments on soluble solids content was observed while the HTP processing slightly increased the acidity of pasteurized tomato juice. The good relationship obtained between brown color and total color difference (TCD) suggests that TCD can be used to evaluate the visual color deterioration and browning in thermally processed tomato juice throughout refrigerated storage. Results presented in this study showed that the combination of a mild heat treatment plus refrigeration may help to ensure the microbiological safety and the nutritional value of pasteurized tomato juices.     

Effect of refrigerated storage on ascorbic acid content of orange juice treated by pulsed electric fields and thermal pasteurization

Application of pulsed electric fields (PEF) can lead to longer shelf life of fruit juices with minimal product quality loss and good retention of fresh-like flavour. The aim of this study was to evaluate the effect of PEF and conventional pasteurization (90 °C, 20 s) on ascorbic acid content of orange juice, and to assess modifications in ascorbic acid concentration of orange juice stored in refrigeration at 2 and 10 °C for 7 weeks. The ascorbic acid degradation rate was −0.0003, −0.0006, −0.0009 and −0.0010 μs⁻¹ for fields of 25, 30, 35 and 40 kV/cm, respectively. With selected PEF treatment (30 kV/cm and 100 μs) the shelf life based on 50% ascorbic acid losses was 277 days for the PEF-treated orange juice stored at 2 °C, while for the pasteurized juice was 90 days.     

Orange Juices and Concentrates Stabilization by a Proteic Inhibitor of Pectin Methylesterase

A proteic inhibitor of pectin methylesterase (PME), recently discovered in kiwi, was used to stabilize cloud of orange juice concentrate with “Cut-back,” 42° Brix. To concentrated and pasteurized orange juice were added increasing amounts of fresh juice (12° Brix) with PME 0.8 U/mL at the fresh to pasteurized ratios 6.6 to 38%. The PME inhibitor (65% pure), from kiwi, was added at 50 mg/L. After 8 mo at 5°C samples were compared with controls containing the same amount of fresh juice with PME inhibited by pasteurization. Pasteurized samples were not different from those treated with PME inhibitor. Conversely, where PME was not inhibited, cloud stability decreased with increasing amounts of fresh juice. Use of kiwi PME inhibitor in fruit juice production has potential advantages.     

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.     

Effect of Oxygen on Taste, Ascorbic Acid Loss and Browning for HTST-Pasteurized, Single-Strength Orange Juice

Single-strength orange juice with dissolved oxygen levels of 0.6, 1.8, 6.5, and 10.1 ppm was pasteurized at 85°C for 7 sec using a pilot-scale, high temperature-short time, tubular, heat exchanger. The product was aseptically bottled under nitrogen and stored for 5 months at 22°C. Browning and loss of ascorbic acid were linearly related to the initial oxygen concentration. Based on the results of sensory evaluation, reducing the initial dissolved oxygen concentration by 94% did not extend the shelf-life of single-strength orange juice. Therefore, based on taste, deaeration will not extend the shelf-life of this product.     

Comparison of high pressure treatment and thermal pasteurization effects on the quality and shelf life of guava puree

The effects of high pressures and thermal pasteurization on the survival of microorganisms, enzyme inactivation and quality changes of guava puree during storage at 4°C were investigated and compared with untreated samples. After treatment at a pressure of 600MPa and 25°C for 15 min, the microorganisms in guava puree were inactivated to less than 10 cfu mL⁻¹ and the product exhibited no change in colour, pectin, cloud and ascorbic acid content as compared with fresh samples. The inactivation of enzymes in guava puree by thermal pasteurization was greater than by high pressures. The microbial count in guava puree reduced to 200 cfu mL⁻¹ and the product showed marked changes in viscosity, turbidity and colour when heated at 88–90°C for 24s. The content of pectin, cloud and ascorbic acid as well as colour in untreated and high pressurized (400MPa) guava puree gradually decreased, whereas these changes were not observed in pasteurized (88–90°C) and high pressurized (6000MPa) puree during storage at 4°C for 60 days. The guava puree treated at 600MPa and 25°C for 15 min retained good quality similar to the freshly extracted puree after storage at 4°C for 40 days.     

Pasteurization of carrot juice by combining UV-C and mild heat: Impact on shelf-life and quality compared to conventional thermal treatment

The combination of UV-C radiation and mild heat (UV-H) treatment is a promising strategy for synergistically increasing microbial inactivation in low UV-transmitting juices. In this research, we explored the suitability of UV-H treatment in carrot juice pasteurization and its impact on juice quality during shelf-life compared to that of thermal pasteurization. UV-H treatment at 60 °C (3.92 J/mL, 3.6 min) enabled reductions of over 5 log₁₀ cycles in the reference pathogens and a significant reduction in spoilage yeasts, bacteria, and bacterial spores. The activity of pectin methylesterase and polyphenol oxidase was reduced by UV-H treatment to levels close to those of low-temperature pasteurization (60 °C/18.1 min). The native population of total aerobic bacteria, lactic acid bacteria, and yeasts and molds of UV-H-treated juice remained undetectable during 29 days of cold storage. Furthermore, viscosity, cloud stability, and the color of fresh juice were better preserved by UV-H treatment than by thermal pasteurization throughout storage.Industrial relevanceThis study demonstrates that UV-H treatment is a beneficial alternative to conventional thermal processing in carrot juice pasteurization, since appropriate inactivation levels of pathogenic and spoilage microorganisms can be reached while better preserving the quality attributes of fresh juice throughout its shelf-life.     

Changes in Quality and Nutritional Parameters During Refrigerated Storage of an Orange Juice–Milk Beverage Treated by Equivalent Thermal and Non-thermal Processes for Mild Pasteurization

The effects of high-pressure (HP) treatment (400?MPa at 42 °C for 5 min) and pulsed electric field (PEF) processing (25 kV/cm at 57 °C for 280 μs) on ascorbic acid, total carotenoids, total phenolic compounds and total antioxidant capacity (TEAC and ORAC) of an orange juice–milk (OJ-M) beverage along the storage time at 4 °C were compared with a conventional heat preservation technology used in industry (90 °C for 15 s). During storage, ascorbic acid, total carotenoids and antioxidant capacity (TEAC) depleted with time regardless of the treatment applied. Instead, total phenolic content and antioxidant capacity measured by the ORAC method increased at the end of the storage. Non-thermal-treated beverage had less non-enzymatic browning than the thermally pasteurized one. There were no significant variations in the hidroxymethylfurfural (HMF) content of the HP- and PEF-treated OJ-M, whilst a significant increase was obtained after thermal treatment. During refrigerated storage, HMF was always below the maximum values established. The HP treatments reduced the L* value of the treated beverages immediately after processing and during refrigerated storage and induced an increase in total colour differences of beverages treated by HP compared with PEF and thermally processed orange juice–milk. Hence, alternative methods such as HP and PEF may give new opportunities to develop orange juice–milk with an equivalent shelf life to that of thermally treated orange juice mixed with milk in terms of microbial, physicochemical and nutritional characteristics.     

Time and Temperature Effect on Stability of Moroccan Processed Orange Juice during Storage

The loss of quality of processed pasteurized orange juice stored at 4°C, 22.5°C, 35°C, and 45°C for up to 14 wks was evaluated. The results showed that parameters such as pH, total solids, titratable acidity, formal index, and total sugars did not significantly change during storage at all temperatures. However, a major change was observed for ascorbic acid content, reducing sugars and furfural production, except for storage temperature at 4°C. Ascorbic acid degradation, sucrose hydrolysis, and furfural build-up followed pseudo-zero order reaction kinetics. The minimal change of formol number and total sugars suggested that nonenzymatic browning was mainly due to ascorbic acid degradation. Fufurfal formation during storage was found to be much higher than that reported in the literature.     

Comparing the impact of high pressure,pulsed electric field and thermal pasteurization on quality attributes of cloudy apple juice using targeted and untargeted analyses

The impact of low-oxygen spiral-filter press technology combined with thermal pasteurization (TP), pulsed electric field (PEF) and high pressure processing (HPP) on cloudy apple juice quality was investigated immediately after the treatments and after 3 weeks of storage at 4 °C. Based on equivalent levels of microbial safety and desired shelf-life, low and high processing intensities were selected: TP (72 °C/15 s; 85 °C/30 s), PEF (12.5 kV/cm, 76.4 kJ/L; 12.3 kV/cm, 132.5 kJ/L), and HPP (400 MPa/3 min; 600 MPa/3 min). High intensity thermal treatment resulted in a bright, yellowish color which was maintained during storage. PPO and POD activities were largely reduced by high intensity PEF and TP yet showed high resistance to HPP. The highest vitamin C content was provided by fresh juice followed by PEF-treated juices. Due to oxidative degradation reactions, vitamin C of all treated samples significantly decreased during storage. Immediately after processing, high cloud stability values were obtained in all samples; however, cloud stability decreased during storage particularly for HPP juices with high residual PME. No significant changes were observed in pH, titratable acidity, organic acid and sugar content which also corresponded to sweet and sour taste. Results from untargeted volatile profiles showed that esters increased after PEF and were better retained after HPP. Contrary to TP treatment where ester degradation reactions occurred together with the formation of off-flavors. Most of the volatiles decreased during storage which could be linked to oxidation and ester hydrolysis reactions.Industrial relevanceBeing one of the most popular fruit juices consumed worldwide, cloudy apple juice can still undergo quality changes such as color degradation, cloud loss (fast sedimentation) and flavor changes during processing and storage. This study evaluates the potential of low-oxygen spiral-filter press in combination with different preservation technologies to obtain a maximal quality of cloudy apple juice. Results showed that high intensity thermal pasteurization can effectively inactivate quality-degrading enzymes, therefore it is useful to obtain an optimal cloudy apple juice product in terms of color and cloud stability. Although HPP has minimal impact on aroma of the juice, shelf-life of the juice may be limited due to incomplete enzyme inactivation. In the case of PEF treatment, thermal effects may contribute to maintain apple juice quality.     

Quality degradation kinetics of pasteurised and high pressure processed fresh Navel orange juice: Nutritional parameters and shelf life

A kinetic study of post processing quality loss was conducted after high pressure processing (600 MPa, 40 °C, 4 min) or thermal pasteurisation (80 °C, 60 s) of fresh Navel orange juice. Selection of processing conditions was mainly based on pectin methylesterase inactivation. Ascorbic acid loss, colour, viscosity and sensory characteristics were measured during storage at different isothermal conditions (0–30 °C). Increased shelf life (based on ascorbic acid retention) was achieved for high pressurised compared to thermally pasteurised juice, ranging from 49% (storage at 15 °C) to 112% (storage at 0 °C). Activation energy values for ascorbic acid loss were 68.5 and 53.1 kJ/mol, respectively, for high pressurised and thermally treated juice. High pressure processing resulted in better retention of flavour of untreated juice and superior sensory characteristics compared to thermal pasteurisation. Colour change was linearly correlated to ascorbic acid loss for both types of processing. Slightly higher apparent viscosity values were determined for high pressurised juice.Industrial relevanceApplication of high hydrostatic pressure on orange juice industry. Fresh orange juice is a product of high commercial and nutritional value due to its rich vitamin C content and its desired sensory characteristics. High Hydrostatic Pressure (HHP) is an alternative non-thermal technology that has been proposed for application on orange juice. Such a treatment denaturates enzymes and eliminates microorganisms responsible for spoilage of orange juice without detrimental effects on the sensory and nutritional quality of juice. The effect of HHP on the stability of fresh orange juice has been studied by different research groups, while orange juices processed with the new technology have already been commercially available in Japan, U.S.A., Mexico and Europe. However, a systematic kinetic approach of the effect of HHP on different quality indexes (not only microbial spoilage) immediately after processing, as well as during a long term storage of the processed orange juice is needed, in order to achieve an optimal process design and a successful application of the new technology in orange juice industry. Such kinetic data for parameters related to the quality and nutritional value of fresh orange juice were gathered in the present work providing therefore industry with useful information for the HHP stabilization of orange juice and the production of a high quality product. Due to the great benefits of HHP compared to the conventional pasteurization that emerged from this work regarding the quality, shelf life and nutritional characteristics of fresh orange juice, HHP technology is an advantageous alternative process for high valued products like orange juice.     

Use of redox potential modification by gas improves microbial quality, color retention, and ascorbic acid stability of pasteurized orange juice

The aim of this paper was to study the effect of both redox potential (Eh) and pasteurization of orange juice on stability of color and ascorbic acid, and growth recovery of microorganisms during storage at 15 degrees C for 7 weeks. Three conditions of Eh, +360 mV (ungassed), +240 mV (gassed with N2), and -180 mV (gassed with N2-H2) were applied to orange juice. Both thermal destruction and recovery of sublethally heat-injured cells of Lactobacillus plantarum and Saccharomyces cerevisiae were investigated. While oxidizing conditions were the most effective for thermal destruction of L. plantarum and S. cerevisiae, reducing conditions decreased recovery of heated cells of S. cerevisiae. In addition, gassing the juice with N2 or N2-H2 increased color retention and ascorbic acid stability. The present study demonstrated that juice must be reduced just after the heat treatment in order, firstly, to maximize microbial destruction during pasteurization, and secondly, to prevent the development of microorganisms and stabilize color and ascorbic acid during storage.     

Effects of ultrafiltration combined with high-pressure processing,ultrasound and heat treatments on the quality of a blueberry–grape–pineapple–cantaloupe juice blend

This study investigated the effect of ultrafiltration (UF) combined with high-pressure processing (HPP) at 550 MPa, 25 °C for 5 min, ultrasound (US) at 520 W, 40 °C for 10 min and heat treatment (HT) at 90 °C for 3 min on the microbial, physicochemical and sensory properties of a blueberry–grape–pineapple–cantaloupe juice blend during 104 days of storage at 4 °C. After UF, the shelf life of the HPP- and US-treated clear juice blends were 104 and 72 days during the storage at 4 °C respectively. HPP, US and HT treatment minimally affected the anthocyanin and total phenol contents, while HPP better maintained the ascorbic acid levels and sensory properties in the clear juice blend during the storage. Therefore, HPP combined with UF was identified as a prospective processing technique in the fruit juice industry.     

Chemical Changes during Storage of an Alcoholic Orange Juice Beverage

Chemical stability of a pasteurized, noncarbonated, alcoholic orange juice beverage, (8% ethanol and 30% reconstituted Valencia frozen concentrated orange juice), was investigated. It was hot-filled into clear glass bottles under nitrogen and subjected to 14-wk storage at 4, 25, and 40°C. pH, °Brix, titratable acidity, and % alcohol remained constant throughout storage. Accumulation of furfural and darkening paralleled ascorbic acid degradation. The beverage exhibited 25 times more browning at 40°C and 9 times more at 25°C than at 4°C after 14-wk. d-Limonene decreased at all temperatures. Nitrogen headspace slightly improved stability at 40°C. Time and temperature were most significant in storage and long-tem shelf-life could only be achieved with refrigeration.     

Effects of ascorbic acid retention on juice color and pigment stability in blood orange (Citrus sinensis) juice during refrigerated storage

Blood orange juice samples with two different levels of ascorbic acid content were placed in HDPE plastic bottles, pasteurized, and stored at 4.5 °C. The influence of ascorbic acid retention on color stability of blood orange juice was investigated using CIE L*a*b*, hue, chroma, polymeric color, and browning index during the storage period. Changes in monomeric anthocyanin pigments, total carotenoid contents, cyanidin-3-glucoside, and ascorbic acid were also measured. Ascorbic acid degradation was highly correlated (r>0.93) to anthocyanin pigment degradation. Ascorbic acid content also showed linear correlation with red color intensity (CIE a*, and chroma) in the juice. Polymeric color and browning index increased with storage time and were more pronounced for juice fortified with ascorbic acid.     

Accelerated storage and isothermal microcalorimetry as methods of predicting carrot juice shelf‐life

The possibility of predicting the shelf‐life of pasteurized carrot juice by isothermal microcalorimetry or change in pH was investigated and compared with traditional plate count results. A small increase in thermal power (2 µW), maximal increase of and acceleration of thermal power all gave rapid, well‐correlated results for the shelf‐life, as did pH, during accelerated storage. The effect of accelerated storage (17 °C) on the microbial flora of pasteurized carrot juice was also compared with the flora from storage at 8 °C, and it was found that accelerated storage is feasible for the rapid evaluation of shelf‐life, but that the microbial flora in the spoilt juice will be different. Copyright © 2004 Society of Chemical Industry     

Changes in bioactive compounds and antioxidant activity during homogenization and thermal processing of tomato puree

The effect of homogenization and thermal processing on a number of bioactive compounds (carotenoids, total phenolics, ascorbic acid and folates) in both raw tomato puree (RTP) and “hot break” tomato puree (HTP) was investigated. RTP and HTP were homogenized in either one or two-steps, followed by pasteurization at 98 °C for 40 s. Additionally, HTP was pasteurized in parallel at 98 °C, 108 °C and 128 °C. In general, homogenization had no effect, but changes were observed after pasteurization (98 °C for 40 s). Carotenoids were relatively resistant to thermal degradation, whereas total phenolic content and ascorbic acid significantly decreased. However, a higher content of folates was determined in the homogenized and pasteurized samples due to their higher extraction from the subcellular compartment. The increase in pasteurization temperatures of the HTP up to 128 °C led to a decrease of ascorbic acid, total phenolic compounds and folates. In conclusion, homogenization and pasteurization at 98 °C for 40 s improves the nutritional value of tomato puree, increasing the extractability of the folates and maintaining the carotenoid content.Industrial relevanceUnlike other vegetables, the tomato is a staple food that is not frequently homogenized by the processing industry, although homogenization could improve product quality. This is why we explored this technique, using one-step and two-step homogenization. The tomato and vegetable processing industry frequently pasteurizes at a constant flow rate, meaning constant heating time. In this study, we employed three different temperatures, using the same time of exposure, to cover different situations in the food industry. Depending on the product’s thickness, an increase in the temperature might be needed to reduce any microbiological hazard in the final product. Homogenization followed by pasteurization at 98 °C for 40 s resulted in a greater improvement of the nutritional value of tomato puree in all situations tested.     

Preservation of mango juice by freezing and canning

In this work the preservation of mango juice by freezing and canning was compared. The following results were obtained: The loss of ascorbic acid during the preparation of canned mango juice is mainly due to the processing steps other than retorting which had the least harmful effect. The retention of ascorbic acid and carotene after canning and freezing was nearly the same. Both freezing and canning caused no marked changes in the pectin content. The inactivation of the pectin methylesterase was more obvious after canning than after freezing. Reducing sugars slightly increased after freezing and canning, while the acidity and pH showed no appreciable changes. The chemical constituents except the sugars of the commercial samples were lower than those of the experimental samples. During storage, the percentage retention of ascorbic acid and carotene were lower when pasteurization was not included, and in canned samples they were higher in the experimental juice than in the market samples. Pectin content showed no changes in all cases studied. The activity of pectin methylesterase slightly decreased in frozen samples, while it was a small increase in case of canned juices. During storage the microbial count of frozen and canned samples decreased when storage progressed. The addition of water and sugar during manufacturing of commercial samples did not help to obtain a product with good storage stability. There was a significant difference between the characteristics of frozen pasteurized and non pasteurized mango juice. It seems very important to pasteurize mango juice before storage in a frozen form.