Changes in orange juice color by addition of mandarin juice

The most natural way of improving the color of orange juices is by adding other juices, which provide a more intense coloration. The US legislation allows the addition of up to 10% of mandarin juice to the orange juice to improve its color. The first objective of this study was to compare the color characteristics of juices from 11 mandarin cultivars, currently being grown in Spain. Experimental results proved that only the green-red coordinate, a*, of the orange juices can be improved by adding mandarin juice. The mandarin cultivar that provided a juice with the highest values of a* was Clemenules. Once this selection was made, the effects of adding mandarin juice at different ratios, up to 10%, on the color characteristics of the orange juice were studied. Values of the a* coordinate went from 5.50 for the pure orange juice up to 6.29 for the mixture of 90% orange juice plus 10% of mandarin juice. Finally, hedonic tests proved that regular juice consumers preferred the color of mandarin juice to that of orange juice and that they liked better the color of the juice mixture containing 10% mandarin juice than that containing 3% mandarin juice.     

Influence of flavour absorption by food-packaging materials (low-density polyethylene, polycarbonate and polyethylene terephthalate) on taste perception of a model solution and orange juice

The influence of flavour absorption by low-density polyethylene (LDPE), polycarbonate (PC) and polyethylene terephthalate (PET) on taste perception of a model solution containing seven flavour compounds and orange juice in glass bottles was studied with and without pieces of the respective plastic films after dark storage at 20°C. Owing to absorption, the amount of flavour compounds in the model solution exposed to LDPE decreased substantially. From the model flavour solution valencene was almost completely absorbed by LDPE, followed to a lesser extent by decanal, hexyl acetate, octanal and nonanone. Less flavour compounds were absorbed from the model solution by PC and PET. In contrast to LDPE, valencene was absorbed in the lowest amounts and decanal in the highest. Limonene was readily absorbed from orange juice by LDPE, while myrcene, valencene, pinene and decanal were absorbed in smaller quantities. Only three flavour compounds were absorbed from orange juice by PC and PET in very small amounts: limonene, myrcene and decanal. Although the flavour content between controls and polymer-treated samples differed substantially, the loss of flavour compounds due to absorption by LDPE, PC and PET did not influence taste perception of a model solution and orange juice significantly up to 29 days of dark storage at 20°C as determined by triangular taste panel tests.     

Stability of enterocin AS-48 in fruit and vegetable juices

Enterocin AS-48 is a candidate bacteriocin for food biopreservation. Before addressing application of AS-48 to vegetable-based foods, the interaction between AS-48 and vegetable food components and the stability of AS-48 were studied. Enterocin AS-48 had variable interactions with fruit and vegetable juices, with complete, partial, or negligible loss of activity. For some juices, loss of activity was ameliorated by increasing the bacteriocin concentration, diluting the juice, or applying a heat pretreatment. In juices obtained from cabbage, cauliflower, lettuce, green beans, celery, and avocado, AS-48 was very stable for the first 24 to 48 h of storage under refrigeration, and decay of activity was markedly influenced by storage temperature. In fresh-made fruit juices (orange, apple, grapefruit, pear, pineapple, and kiwi) and juice mixtures, AS-48 was very stable for at least 15 days at 4 degrees C, and bacteriocin activity was still detectable after 30 days of storage. Gradual and variable loss of activity occurred in juices stored at 15 and 28 degrees C; inactivation was faster at higher temperatures. In commercial fruit juices (orange, apple, peach, and pineapple) stored at 4 degrees C, the bacteriocin was completely stable for up to 120 days, and over 60% of initial activity was still present in juices stored at 15 degrees C for the same period. Commercial fruit juices stored at 28 degrees C for 120 days retained between 31.5% (apple) and 67.71% (peach) of their initial bacteriocin activity. Solutions of AS-48 in sterile distilled water were stable (120 days at 4 to 28 degrees C). Limited loss of activity was observed after mixing AS-48 with some food-grade dyes and thickening agents. Enterocin AS-48 added to lettuce juice incubated at 15 degrees C reduced viable counts of Listeria monocytogenes CECT 4032 and Bacillus cereus LWL1 to below detection limits and markedly reduced viable counts of Staphylococcus aureus CECT 976.     

Carotenoid and flavanone content during refrigerated storage of orange juice processed by high-pressure, pulsed electric fields and low pasteurization

The impact of different processing technologies, including non-thermal technologies, on bioactive compounds of orange juice was investigated. Freshly squeezed orange juice was treated by high pressure (HP) (400 MPa/40 °C/1 min), pulsed electric fields (PEF) (35 kV cm⁻¹/750 μs) and low pasteurization (LPT) (70 °C/30 s). The stability of main carotenoids and flavanones was studied just after treatment and during 40 days of refrigerated storage at 4 °C. Just after treatment, HP juice showed a significant increase on total carotenoid and flavanone content extracted (45.19 and 15.46%, respectively) and on vitamin A value (30.89%) with regard untreated juice, whereas no significant changes were observed for PEF and LPT juices. For all treated orange juices, flavanone content decreased significantly (around 50%) during the first 20 days of storage at 4 °C while carotenoid content showed a moderate decrease (less than 11%) that took place during the last 20 days. In general, during refrigerated storage, carotenoids and flavanones remained higher in HP juice than in LPT and PEF juices. Hence, HP and PEF technologies were as effective o even more than LPT to preserve bioactive compounds in orange juice during refrigerated storage.     

The reduction of patulin in apple juice by three different types of activated carbon

Three types of activated carbon (NORIT SA 4, NORIT SX 4 and NORIT CA 1) were investigated for their ability to reduce patulin levels in apple juice at various Brix levels and temperatures. The steamactivated carbons (NORIT SA 4 and NORIT SX 4) exhibited similar adsorption isotherms at a dosage level of 1g/l. They achieved patulin reductions of 80% and 70% respectively in 12° Brix juice at 55°C. The similarity in performance between the steam-activated carbons implies that the purity and the surface acidity does not influence the adsorption of patulin. Chemically-activated carbon (NORIT CA 1) was less effective in removing patulin and achieved only a 45% reduction at a dose of 1g/l. Patulin removal was influenced by juice Brix in that higher carbon doses were required at higher Brix levels for equivalent removal efficiency. At a dose of 1g/l, NORIT SA 4 removed only 45% patulin from a 20° Brix juice. The removal of patulin from either 12 or 20° Brix juice by NORIT SA 4 at 1g/l was not influenced by temperature changes in the range 30 to 65°C.     

Profile and levels of bioactive amines in orange juice and orange soft drink

The levels of bioactive amines, pH, soluble solids, acidity, specific gravity, and total sugars were determined in different brands of orange products. Nine amines were detected in orange juice at mean total levels of 53.5 mg l⁻¹. There were significant differences, among orange juice brands, in the levels of spermidine, synephrine, spermine, octopamine, pH and total acidity. Five amines were detected in soft drinks with mean total levels of 3.85 mg l⁻¹. There were significant differences, among orange soft drink brands, in the levels of most amines and the physicochemical characteristics. The predominant amine was putrescine, followed by synephrine and spermidine, in both orange juices and soft drinks. The levels of these amines in the soft drink varied from 5.0% to 7.6% of the mean levels in orange juice, suggesting that less than 10% of orange juice could have been used in the soft drink.     

Stability of black carrot anthocyanins in various fruit juices and nectars

Fruit juices (apple, grape, orange, grapefruit, tangerine and lemon) and nectars (apricot, peach and pineapple) were coloured with black carrot juice concentrate and stability of black carrot anthocyanins in these matrices was studied during heating at 70–90 °C and storage at 4–37 °C. Anthocyanin degradation, in all coloured juices and nectars, followed first-order reaction kinetics. During heating, black carrot anthocyanins in apple and grape juices showed higher stability than those in citrus juices at 70 and 80 °C. High stability was also obtained for the anthocyanins in peach and apricot nectars at these temperatures. Black carrot anthocyanins were the least stable in orange juice during both heating and storage. During storage, degradation of anthocyanins was very fast at 37 °C, especially in pineapple nectar. Refrigerated storage (4 °C) markedly increased the stability in all samples. Activation energies for the degradation of black carrot anthocyanins in coloured juices and nectars ranged from 42.1 to 75.8 kJ mol⁻¹ at 70–90 °C and 65.9–94.7 kJ mol⁻¹ at 4–37 °C.     

Effect of refrigerated storage on vitamin C and antioxidant activity of orange juice processed by high-pressure or pulsed electric fields with regard to low pasteurization

A better knowledge of the effect of refrigerated storage on the nutritional and antioxidant characteristics of foods processed by emerging technologies with regard to thermal traditional technology is necessary. Thus, freshly squeezed orange juice was processed by high-pressure (HP) (400 MPa/40 °C/1 min), pulsed electric fields (PEF) (35 kV/cm/750 μs) and low pasteurization (LPT) (70 °C/30 s). The stability of vitamin C and antioxidant activity was studied just after treatment and during 40 days of refrigerated storage at 4 °C. The determination of total vitamin C (ascorbic acid plus dehydroascorbic acid) was achieved by HPLC whereas the antioxidant activity was assessed by the measurement of the DPPH• radical scavenging. Just after treatment, all treated orange juices showed a decrease lower than 8% in vitamin C content compared with the untreated one. At the end of refrigerated storage, HP and LPT juices showed similar vitamin C losses (14 and 18%, respectively) in relation to untreated juice, although HP juices maintained better the vitamin C content during more days than LPT juices. Regarding antioxidant activity, after 40 days at 4 °C, differences among treated juices were no significant in terms of antiradical efficiency (AE=1/EC₅₀T_EC50). HP and PEF may be technologies as effective as LPT to retain antioxidant characteristics of orange juice during refrigerated storage.     

The growth of Propionibacterium cyclohexanicum in fruit juices and its survival following elevated temperature treatments

This study investigated the growth of Propionibacterium cyclohexanicum in orange juice over a temperature range from 4 to 40 degrees C and its ability to multiply in tomato, grapefruit, apple, pineapple and cranberry juices at 30 and 35 degrees C. Survival after 10 min exposure to 50, 60, 70, 80, 85, 90 and 95 degrees C in culture medium and in orange juice was also assessed. In orange juice the organism was able to multiply by 2 logs at temperatures from 4 to 35 degrees C and survived for up to 52 days. However, at 40 degrees C viable counts were reduced after 6 days and no viable cells isolated after 17 days. The optimum growth temperature in orange juice over 6 days was 25 degrees C but over 4 days it was 35 degrees C. The growth of P. cyclohexanicum was monitored in tomato, grapefruit, cranberry, pineapple and apple juices at 30 and 35 degrees C over 29 days. Cranberry, grapefruit and apple juice did not support the growth of P. cyclohexanicum. At 30 degrees C no viable cells were detected after 8 days in cranberry juice or after 22 days in grapefruit juice while at 35 degrees C no viable cells were detected after 5 and 15 days, respectively. However, in apple juice, although a 5 log reduction occurred, viable cells could be detected after 29 days. P. cyclohexanicum was able to multiply in both tomato and pineapple juices. In tomato juice, there was a 2 log increase in viable counts after 8 days at 30 degrees C but no increase at 35 degrees C, while in pineapple juice there was a 1 log increase in numbers over 29 days with no significant difference between numbers of viable cells present at 30 and 35 degrees C. The organism survived at 50 degrees C for 10 min in culture medium without a significant loss of viability while similar treatment at 60, 70 and 80 degrees C resulted in approximately a 3-4 log reduction, with no viable cells detected after treatment at 85 or 90 or 95 degrees C but, when pre-treated at intermediate temperatures before exposure to higher temperatures, some cells survived. However, in orange juice a proportion of cells survived at 95 degrees C for 10 min without pre-treatment and there was no significant difference between numbers surviving with and without pre-treatment. The results from this study demonstrate that P. cyclohexanicum is able to grow in a number of juices, other than orange juice, and able to survive a number of high temperature procedures. Therefore, if initially present in the raw materials P. cyclohexanicum might survive the pasteurization procedures used in the fruit juice industry, contaminate and consequently spoil the final product.     

Survival of human norovirus surrogates in milk, orange, and pomegranate juice, and juice blends at refrigeration (4 °C)

Fresh fruits, juices, and beverages have been implicated in human noroviral and hepatitis A virus outbreaks. The purpose of this study was to determine the survival of human norovirus surrogates (murine norovirus, MNV-1; feline calicivirus, FCV-F9; and bacteriophage MS2) in juices (orange and pomegranate juices), juice blends (pomegranate and orange juice) and milk over 0, 1, 2, 7, 14, and 21 days at refrigeration (4 °C). Juices, juice blends, and milk were inoculated with each virus over 21 days, serially diluted in cell culture media, and plaque assayed. MNV-1 showed no reduction in titer after 21 days in orange juice and milk, but moderate reduction (1.4 log) in pomegranate juice from a titer of 5 log(10) PFU/ml. However, MNV-1 was completely reduced after 7 days in the orange and pomegranate juice blend. FCV-F9 from a titer of 6 log(10) PFU/ml was completely reduced after 14 days in orange as well as pomegranate juice and by ～ 3 logs after 21 days in milk at 4 °C. Interestingly, FCV-F9 was completely reduced after 1 day in the orange and pomegranate juice blend at 4 °C. MS2 was reduced by ～ 1.28 log after 21 days in orange juice from a titer of 6 log(10) PFU/ml, and <1 log after 21 days in milk or pomegranate juice, with juice blends showing minimal reduction (<1 log) after 21 days at 4 °C. These results show the survival pattern of noroviruses that aid in the transmission of foodborne viral outbreaks. The data obtained can be used in quantitative viral risk assessment studies and to develop improved measures to prevent virus survival towards controlling outbreaks.     

Effect of storage in juice with or without pulp and/or calcium lactate on the subsequent survival of Escherichia coli O157:H7 in simulated gastric fluid

A study was conducted to evaluate the effect of storing Escherichia coli O157:H7 in fruit or vegetable juices with or without pulp and/or calcium lactate, on the bacterial resistance to a simulated gastric fluid (SGF, pH 1.5). Apple, carrot, orange, and tomato juices containing pulp or freed from pulp by filtration were used in this study. Calcium lactate at about 1.4 g/l was added to juices to obtain calcium supplemented juices. Juices with or without pulp and/or calcium lactate were inoculated with E. coli O157:H7 and then were stored at 7 degrees C for 0, 1, 2, or 4 days. The acid resistance of cells stored in juices with or without pulp and/or calcium lactate was determined by incubating in SGF for 90 or 240 min at 37 degrees C. Cells stored in apple juice for 4 days, carrot juice for 2 days, and orange juice for 4 days with pulp only had greater acid resistance, while all cells stored in tomato juice with pulp had greater acid resistance than cells stored in juice without pulp. The D-values of cells stored in supplemented apple and orange juices with calcium lactate declined 1.7-3.5 fold, whereas D-values of cells stored in supplemented tomato juice decreased by about 1.4-fold when compared to cells stored in juice without calcium lactate after exposure in SGF. These results indicate that storing E. coli O157:H7 in juices with pulp had little or no effect on the acid resistance of cells during subsequent exposure in SGF. Calcium lactate supplemented into juices could dramatically decrease the ability of E. coli O157:H7 to survive in SGF, possibly reducing the risk of foodborne illness by juice products.     

STABILITY OF ASCORBIC ACID IN ORANGE JUICES AFTER INITIAL USE AT HOME BEGINS

Ascorbic acid (AA) stability in orange juices, both fresh and commercially packaged in different types of containers (Tetrabrik, glass and tin), was studied. The purpose was to ascertain how well AA is retained once use at home has commenced. The AA levels of the orange juices were measured at 0, 1, 3, 5, 67, 24, 48, 72 and 168h following squeezing in the case of fresh oranges and for commercially packaged juices following opening of the container. Storage was at 4 or 25C. Fresh juice was stored in an open jar; packaged juice in the container in which it came. When stored 7 days at 4C, retention ranged from 93.8 to 95%.     

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.     

Application of a multi-pass high-pressure homogenization treatment for the pasteurization of fruit juices

This work evaluates both the effects of a multiple-pass high-pressure homogenization treatment on the microbial inactivation of selected microbial strains (Saccharomyces cerevisiae, Lactobacillus delbrueckii, Escherichia coli) inoculated into commercial fruit juices (orange, red orange, pineapple) as well as the application of this non-thermal technology to the pasteurization of fresh juices (Annurca apple juice). The pressure level ranged from 50 to 250 MPa, the number of passes from 1 to 5 and the inlet temperature from 2 to 20 °C.Preliminary tests in distilled water showed that the efficiency of the multiple-pass treatment significantly depends on both the homogenizing pressure as well as the microbial species. The subsequent extension of the multiple-pass treatment to the inactivation of S. cerevisiae inoculated into three different fruit juices (orange, red-orange and pineapple juice) highlighted that the inactivation induced by the high pressure treatment did not depend on the properties of the tested juices and was not statistically different from inactivation in water (p value < 0.05). These findings were supported by the comparison of two different mathematical models used to fit the inactivation kinetics, whose fitting parameters were not significantly different for water and the fruit juices for any pressure level applied.Three homogenization passes at 150 MPa and 25 °C, which resulted to be optimal for yeast inactivation in fruit juices, were effective for the stabilization of the endogenous microbial load of fresh Annurca apple juice. The treated apple juice showed a minimum shelf-life of 28 days under refrigerated conditions, during which the natural qualities of the fresh juice were completely preserved.     

High pressure processing of Australian navel orange juices: Sensory analysis and volatile flavor profiling

Navel orange juices subjected to high pressure processing (HPP) and temperature treatment (TT) were stored at 4 and 10 °C for up to 12 weeks to establish the shelf-life of such products. The processed juices and a control juice, stored at − 20 °C, were assessed by a trained sensory panel and a consumer acceptance panel at 0, 1, 2, 4, 8 and 12 weeks or until such time that the juices were considered unfit for consumption. Untreated juice stored at 4 °C was similarly assessed for up to 2 weeks and untreated juice stored at 10 °C was assessed for up to 1 week. The volatile components of corresponding juices were isolated by SPME and the extracts were analyzed by GC–MS. Twenty key aroma compounds were selected for quantification and these data were used to monitor the change in volatile content of the juices during storage. The study showed that the odor and flavor of the HPP juice was acceptable to consumers after storage for 12 weeks at temperatures up to 10 °C. However, only the TT juice stored at 4 °C was acceptable after the same length of storage.

Industrial relevance

Orange juice is a sensitive product subject to a high microbial load that can tolerate only moderate heat treatment without the destruction of the product’s delicate aroma and flavor characteristics. High pressure processing at moderate pressures and storage at refrigeration temperatures have been evaluated as means of maximizing microbial inactivation while maintaining consumer acceptability of the product. The sensory and analytical data presented demonstrate that high pressure processing with refrigeration can extend the shelf-life of orange juice while maintaining consumer acceptability.     

Adaptation of Salmonella spp. in juice stored under refrigerated and room temperature enhances acid resistance to simulated gastric fluid

The objective of this study was to evaluate the acid resistance of Salmonella spp. adapted in juices stored under refrigeration and room temperatures to simulated gastric fluid (SGF, pH 1.5). Five Salmonella serovars, Agona, Gaminara, Michigan, Montevideo, and Poona were used in this study. Apple, orange, and tomato juices inoculated with five serovars were stored at refrigeration (7 degrees C) and room temperature (20 degrees C) for 24 h for adaptation. Acid resistances of serovars adapted in juice were determined in SGF at 37 degrees C. All acid-adapted Salmonella serovars in juices displayed enhanced survival time compared to non-adapted controls. Among serovars, S. Poona adapted in apple at 20 degrees C and orange juices at 7 and 20 degrees C showed >2.0 log cfu/ml survivors, while the other serovars decreased to non-detectable level or <2.0 log cfu/ml for 100 s in SGF. Unlike apple and orange juices, all serovars adapted in tomato juice survived with >2.0 log cfu/ml for 100 s. For D-values, all Salmonella serovars adapted in apple and tomato juice enhanced their acid resistances compared to orange juices. S. Agona adapted in tomato juice at 7 degrees C and S. Poona in apple juice at 20 degrees C had the highest D-values with 82.9 and 82.5s, respectively. Results showed that the adaptation in juice increased acid resistance in SGF and varied by serovar, juice type, and adaptation temperature. Therefore, this study indicates that the introduction of Salmonella spp. to an acidic juice environment during processing can enhance their ability to survive in a human stomach, possibly increasing the risk of a Salmonella outbreak by juice.     

Effects of β‐cyclodextrin addition and farming type on vitamin C,antioxidant activity,carotenoids profile,and sensory analysis in pasteurised orange juices

The effects of organic farming, pasteurisation and addition of β‐cyclodextrin on the content of vitamin C, colour, carotenoids and antioxidant capacity of orange juices were studied. After pasteurisation at 98 °C (20 s) and subsequently storage along 145 days at room temperature (20–25 °C), the loss of vitamin C content was around 30%. The effects of the thermal process on carotenoid were clearly observed in lutein (loss of 16% for organic and traditional 8%) and especially β‐cryptoxanthin (loss of 30%). The colour changes were noticeable after the pasteurisation of orange juice and subsequent storage, with significant decreases being observed in lightness and the coordinate a*, while increases were found for coordinates b*, Hue* and chroma. The antioxidant capacity was 0.075 ± 0.01 and 0.053 ± 0.01 mMT mL^?1 for organic and conventional, respectively, with losses around 40% being found at the end of the storage period. The addition of β‐cyclodextrin caused no significant effects on the parameters under analysis. These data showed that strong thermal treatments, such as pasteurisation, adversely affect the nutritional and sensory quality of orange juices.     

Shelf Life and Quality of Freshly Squeezed, Unpasteurized, Polyethylene-Bottled Citrus Juice

Florida's chief orange and grapefruit cultivars were used to produce five freshly squeezed, unpasteurized, polyethylene-bottled juices using commercial conditions. Juices were stored at different temperatures. Shelf life depended primarily on storage temperature: ?1.7°C, 20–23 days; 1.1°C, 16–22 days; 4.4°C, 10–16 days; and 7.8°C, 5–8 days. Staleness was the primary off-flavor limiting shelf life at the three lower temperatures while spoilage with diacetyl was primarily responsible at 7.8°C. At the three lower temperatures, microbial counts generally decreased markedly during storage, while at 7.8°C, an increase was generally noted. Ascorbic acid retention after 2 wk of storage at the three lowest storage temperatures was about 91–93% for two orange juices and 86–88% for the grapefruit juice.     

Estimation of the freezing point of concentrated fruit juices for application in freeze concentration

In freeze concentration operations the fluids remain at temperatures below 0 °C. For a good study of this concentration operation is very important to know the values of freezing point. The aim of this work was to establish a model that predicts the freezing point of fruit juices at various concentrations within the range of interest for freeze concentration (10-40 °Brix). The model proposed relates the freezing point of a juice with the concentrations of main sugars present in the juice: sucrose, glucose and fructose. The freezing point of apple juice, pear juice and peach juice was determined experimentally at various concentrations, and experimental results were well correlated with model calculations.