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.     

基于品质指标的苹果浊汁品种与产地差异性分析

以来自7?个不同主产区的21?个主栽品种,共41?份苹果鲜果为研究对象,对每个品种鲜榨浊汁的出汁率、浊度、果汁颜色、褐变度、透光率、可溶性固形物、可滴定酸、总酚、糖、有机酸、VC、矿物质、抗氧化性等品质指标进行测定。运用描述性分析、逐步线性判别分析进行数据处理。结果表明：不同品种或不同产地的苹果浊汁,品质差异较大。总体来看,a*值、原始浊度、褐变度、可滴定酸、葡萄糖、蔗糖、苹果酸等指标的变幅均较大,分别为94.07%、70.41%、42.86%、35.26%、42.02%、42.40%、37.69%。对于不同品种的苹果浊汁,由于褐变度、总酚、抗氧化性等色泽品质指标以及糖、酸等营养品质指标间具有较大差异,其分布呈现分散状态。其中新红星品种的褐变度、总酚含量、DPPH自由基清除率等品质指标普遍居高,色泽品质差异最显著。富士品种大部分样品的果糖、葡萄糖、蔗糖、苹果酸等指标含量较高,具有较好的营养品质。然而对于不同产地间的样品,其浊度、可滴定酸、可溶性固形物等加工品质指标具有较大差异,样品分布较为分散。河北省样品的出汁率、原始浊度、可滴定酸等指标普遍较低,加工品质较差。来自山东省不同品种苹果浊汁的样品以及来自不同产地富士苹果浊汁的样品间均具有较大差异,并且分别获得了77.8%和72.7%的判别准确率。以上结果表明,不同产地、不同品种苹果原料制得的苹果浊汁存在较大差异,通过对其品质指标进行差异性分析,可为上游育种与种植产业结构调整提供数据基础;通过判别模型的建立实现品种与产地的识别与预测,可以指导企业对苹果原料进行制汁专用化筛选。     

Comparison of High Hydrostatic Pressure,High-PressureCarbon Dioxide and High-Temperature Short-Time Processing on Quality of Mulberry Juice

Changes of microbial, physicochemical and sensory properties of mulberry juice processed by high hydrostatic pressure (HHP) (500 MPa/5 min), high-pressure carbon dioxide (HPCD) (15 MPa/55 °C/10 min), and high-temperature short time (HTST) (110 °C/8.6 s) during 28 days of storage at 4 °C and 25 °C were investigated. Total aerobic bacteria (TAB) and yeast and mold (Y&M) were not detected in HHP-treated and HTST-treated mulberry juices for 28 days at 4 °C and 25 °C, but were detected more than 2 log₁₀ CFU/ml in HPCD-treated mulberry juice for 21 days at 4 °C and 14 days at 25 °C, respectively. Total anthocyanins were retained after HHP and reduced by 4 % after HTST while increased by 11 % after HPCD. Total phenols were retained by HHP, while increased by 4 % after HTST and 16 % after HPCD. The antioxidant capacity was retained by HTST and HHP and increased by HPCD. Both total phenols and antioxidant capacity were decreased during the initial 14 days but then increased up to 28 days regardless of storage temperature. The value of polymeric color and browning index decreased and a* increased in HHP-treated and HPCD-treated mulberry juices, while HTST-treated mulberry juice had a reverse result. The viscosity of mulberry juice increased in HHP-treated and HPCD-treated juices, while decreased in HTST-treated juice. During storage, total anthocyanins, total phenols, and antioxidant capacity and color in all mulberry juices decreased more largely at 25 °C than that at 4 °C. Better quality was observed in HHP- and HPCD-treated mulberry juices, and a longer shelf life was observed in HHP-treated samples compared to HPCD-treated ones.     

EFFECT OF pH AND SOLUBLE SOLIDS ON THE SERUM VISCOSITY AND SERUM COLOR OF TOMATO JUICE AT ELEVATED TEMPERATURES1

Effects of heating time and temperature, pH, and soluble solid levels on serum viscosity and serum color of tomato juice were studied. The samples were canned in 18 mL TDT cans and exposed to processing temperatures of 88C, 102C, and 112C for 30, 60, and 120 min. Depending upon the time and temperature of heating, and initial viscosity of the serum, the losses in viscosity ranged from 3.0–55.6% being higher in serum with higher initial viscosity. Percent losses in serum viscosity during heating of juice increased (6–60%) with increase in pH (3.8–4.9) and soluble solids (6°–24°) in the juice. An increase in pH and soluble solids also enhanced heat induced browning in the serum with values varying from 0.1–2.69.     

Effect of Storage Temperature on the Stability of Aseptically Packaged Concentrated Orange Juice and Concentrated Orange Drink

Commercial orange drink concentrate and two orange juice concentrates were aseptically packed in flexible bags and stored at 4°, 15°, 22°, and 30°C for 6 months. Ascorbic acid, nonenzymatic browning and sensory quality were measured monthly. Sensory characteristics for drink concentrate deteriorated after 3 and 4 months at 30°C and 22°C, respectively. Juice concentrates were unacceptable after 2 and 5 months at 30°C and 22°C, respectively. Drink concentrate ascorbic acid loss was greater than juice concentrates at 4°, 15°, and 22°C. Changes in nonenzymatic browning as measured by Hunter color and by absorbance at 420 nm were similar to changes in other containers. The quality of refrigerated aseptic drink (15°C) and juice (4°C) was similar to frozen concentrates (?18°C).     

Changes in Muscadine Grape Juice Quality During Cold Stabilization and Storage of Bottled Juice

Muscadine grapes (Vitis rotundifolia, Michx.) of two cultivars (Noble and Carlos) were washed and extracted. The resulting juice was cold stabilized for 0, 7 and 60 days at 2°C, then treated, bottled, pasteurized and stored at 2°C and 24°C for 0, 4, 8, and 12 months. Carlos juice was lower in phenols and pH and higher in acidity than Noble. The high total anthocyanins and phenols in the Noble juice caused a significant loss in pigment during cold stabilization. Dilution of juice with 40% water and adjustment of the sugars was beneficial to flavor and color of Carlos, yet 40% dilution was too high for Noble juice. Treatment of either juice with CaCO₃ increased pH and decreased acidity. During 12 months storage, the Carlos juice became darker due to browning, while the Noble juice became lighter by losing pigment, especially at 24°C.     

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

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

高压CO_2对树莓汁品质的影响

研究了高压二氧化碳(High Pressure Carbon Dioxide,HPCD)对树莓汁品质的影响。处理条件为:压强10、20、30MPa,温度35、45、55℃,时间15、30、45、60min。测定其浊度、褐变指数、悬浮稳定性、pH、可溶性固形物含量和色泽。处理后样品褐变指数降低,浊度和悬浮稳定性增加,pH、可溶性固形物含量和色泽没有显著变化。     

超高压与高温短时杀菌对甘蔗汁品质的影响比较

研究了超高压(HHP,500 MPa/4 min)和高温短时(HTST,95℃/15 s)对甘蔗浊汁和清汁p H、可滴定酸(TA)、可溶性固形物(TSS)、总酚、色泽、褐变度、澄清度、浊度和微生物指标的影响,并分析了4℃,贮藏15 d内甘蔗汁品质的变化。结果表明:HTST和HHP处理对甘蔗汁均具有较好的杀菌效果,HHP和HTST甘蔗清汁p H显著降低,HTST甘蔗清汁可滴定酸(TA)含量升高,HHP和HTST对甘蔗清汁和浊汁的可溶性固形物(TSS)和总酚含量无影响,与HTST相比HHP对甘蔗汁颜色的影响较小,HHP处理后甘蔗清汁澄清度升高,甘蔗浊汁浊度下降,HHP甘蔗汁感官性能优于HTST甘蔗汁。经在4℃贮藏15 d,甘蔗浊汁的菌落总数显著升高,但浊汁和清汁的霉菌和酵母菌数基本保持稳定,贮藏期间甘蔗清汁和HTST甘蔗浊汁p H降低,总酚含量均有明显升高,甘蔗清汁的澄清度和甘蔗浊汁的浊度有所降低,HHP甘蔗清汁的b*值和褐变度增加,HTST甘蔗汁颜色稳定。结论:超高压杀菌有利于保持甘蔗汁品质,是适合甘蔗汁的加工技术。      

Kinetics of haze formation and factors influencing the development of haze in clarified apple juice

The rate of haze formation in commercial clarified apple juice stored at 4, 25 and 37°C was monitored over a 16 to 35-week storage period. Changes in turbidity, tannin content and browning index were evaluated. The juice appeared virtually clear and had very little colloidal particles during the initial stages of storage. After 24 weeks, an increase in turbidity of 2.32 NTU was observed for juice samples stored at 37°C. An increase of 0.58 and 0.95 NTU was observed for samples stored at 25 and 4°C, respectively. There was a general decrease in tannin content and an increase in browning index with storage; this effect was most pronounced for samples stored at 37°C. The rate of haze formation and tannin depletion in juice samples followed first-order reaction kinetics. Light and headspace did not affect haze formation. NaCl and CaCl₂ increased haze development while sucrose (up to 60%), urea (0.5 M), and EDTA (up to 0.01 M) had little effect. Addition of sodium dodecyl sulfate retarded haze formation.     

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.     

Comparing the Effects of High Hydrostatic Pressure and Ultrahigh Temperature on Quality and Shelf Life of Cloudy Ginger Juice

The effects of high hydrostatic pressure (HHP) at 500 MPa for 10 min and ultrahigh temperature (UHT) at 110 °C for 8.6 s on the quality of cloudy ginger juice (CGJ) were investigated during storage for 91 days at 4 and 25 °C. The quality aspects studied were microbial stability and selected properties, including pH, total soluble solids (TSS), titratable acidity (TA), total phenols, gingerols, antioxidant capacity, color, and aroma composition. The results showed that HHP treatment led to a 3.0 log cycle reduction of microbial load but did not influence pH, TSS, TA, antioxidant capacity, and color (day 0). Total phenol content increased by 5.31 % after HHP treatment but decreased significantly by 14.74 % after UHT treatment (day 0). Gingerols increased by 14.43 and 14.18 % after HHP and UHT treatments (day 0), respectively. Monoterpenoids, which are the main volatile aroma compounds, did not change significantly after HHP treatment but decreased significantly by 2.27 % after UHT treatment (day 0). During storage, the decreases in total phenols, gingerols, and antioxidant capacity in the UHT-treated GCJ were more noticeable than those in the HHP-treated GCJ. Kinetic data of changes in total phenols, gingerols, and antioxidant capacity fitted into the combined model well. The changes in antioxidant capacity were positively and significantly correlated to total phenols and gingerols. Color darkened and aroma faded in both HHP-treated and UHT-treated CGJs during storage. The quality changes in samples stored at 25 °C were also more noticeable than those stored at 4 °C.     

红枣浑浊汁贮藏过程中浑浊稳定性的研究

为研究红枣浑浊汁在贮藏中的浑浊稳定性,进行了4、25、37℃贮藏枣汁67d的实验。测定了红枣浊汁贮藏过程中浊度、可溶性蛋白、总酚、可溶性固形物、澄清度、褐变指数等指标的变化情况。结果表明:温度对红枣浊汁的浊度影响较大,在贮藏前10d内,25℃贮藏条件下枣汁的浊度最大,贮藏10d后,37℃贮藏条件下的枣汁浊度最大,4℃贮藏条件下的枣汁浊度最小;可溶性蛋白含量随贮藏时间的延长和贮藏温度的升高而降低,贮藏温度对可溶性蛋白含量的影响较为明显;总酚含量随贮藏时间的延长而下降;红枣浑浊汁中可溶性固形物含量在贮藏前20d略有波动,贮藏后期趋于稳定;贮藏温度越高红枣浑浊汁透光率越低,并且在贮藏前10d,红枣浑浊汁的透光率明显增大;贮藏50d以后,透光率呈下降趋势;褐变指数随贮藏时间延长和贮藏温度的升高呈上升趋势;温度对枣汁贮藏过程中稳定性影响较大,贮存温度越高,枣汁的浑浊稳定性越差。实验发现4℃贮藏有利于其原有品质的保持,有利于保持枣汁的浑浊稳定性。      

Storage Stability of Orange Juice Concentrate Packaged Aseptically

Orange juice concentrates were packaged aseptically by a “Dole” aseptic canning machine using 6 oz metal cans. The final juice products (11°, 34°, 44°, 58° Brix) were stored between ?18° and 36°C and tested periodically for nonenzymatic browning, ascorbic acid destruction, furfural and sensory changes. Nonenzymatic browning, the main deterioration phenomena in these products, was satisfactorily retarded at 12°C or lower. Ascorbic acid destruction rate constant was dependent on temperatures between 5 and 25°C, and was affected by degree of juice concentration. Furfural accumulation in juice was higher than that in 58° Brix concentrate. Orange juice concentrate of 58° Brix did not show flavor changes after storage at 5°C or 12°C for 17 or 10 months, respectively, when evaluated after reconstitution to 11° Brix.     

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.     

Comparative study on cloudy apple juice qualities from apple slices treated by high pressure carbon dioxide and mild heat

Qualities of cloudy apple juices from apple slices treated by high pressure carbon dioxide (HPCD) and mild heat (MH) were evaluated. Temperatures were from 25 to 65 °C, time 20 min, and pressure 20 MPa. Polyphenol oxidase (PPO) was completely inactivated by HPCD and its minimal residual activity (RA) by MH at 65 °C was 38.6%. RA of pectin methylesterase (PME) with HPCD was significantly lower than MH and its minimum was 18%. L value of cloudy apple juice from HPCD-treated apple slices was significantly greater than that from MH-treated apple slices, however, b value, browning degree (BD) and turbidity were lower. And no differences in a value, total soluble solids, pH and conductivity were observed. After 7-day storage at 4 °C, HPCD caused no BD alteration but a significant turbidity loss. MH increased BD at 55 and 65 °C, and led to turbidity loss from 35 to 65 °C. The turbidity was not well related to RA of PME.Industrial relevanceCloudy apple juice is one of the popular fruit juices, and it requires strict processing treatment conditions to protect its quality, especially to prevent enzymatic browning and cloud loss. HPCD is one promising novel non-thermal technique and is likely to replace or partially substitute thermal processes. This study analyzed the effect of HPCD as a pretreatment means on qualities of cloudy apple juice, including inactivating enzymes which are crucial to quality control. Available data provided in this study will benefit the fruit juice industry.     

Causes of Browning in Pear Juice Concentrate During Storage

Pear juice was treated with cation exchange resin, PVPP, XAD-4, oxygen, and various resin combinations. Samples were concentrated and increases in browning measured during storage at 37°C. Analytical determinations included α-amino nitrogen, total phenolics, metal ions, ascorbic acid, and dehydroascorbic acid. While XAD-4 and PVPP were more effective in lowering phenolic content and reducing initial color, cation exchange treatment removed amino acids and was most effective in preventing browning and providing flavor stability. Addition of glycine to cation-exchange treated samples restored browning rates. Reductone formation during storage resulted in an apparent increase in ascorbic acid. It was concluded that Maillard browning reactions predominated during storage.     

Comparison of UV-C and thermal treatments for the preservation of carrot juice

The aim of the present study was to investigate the effectiveness of UV-C and thermal treatments on the shelf life of carrot juice. Carrot juice samples were exposed to UV-C radiation and thermal treatment. After the treatments, all carrot juice samples were stored at 4 °C for 16 days. Parameters taken into account were: physicochemical [colour values (L*, a*, and b*) and browning index, viscosity, optical density, density, pH, turbidity], microbiological [total plate count mesophilic, total plate count psychrotrophic, lactic acid bacteria Enterobacteriaceae and yeast and moulds) and sensory attributes. Results showed that the shelf life of carrot juice samples was 4 days for the fresh (control samples) and increased to 12 days for the thermally and UV-Ctreated, respectively. In addition, no significant changes occurred in the investigated physicochemical parameters, while sensory characteristics were not downgraded by UV-C treatment. Present results obtained, support the use of UV-C technology for improving shelf life stability of carrot juice.     

Effects of fining treatment and storage temperature on the quality of clarified banana juice

The clarified banana juice was subjected to different treatment namely bentonite, combination of gelatin and bentonite and control and stored at 4, 25 and 37 °C for 24 weeks. The effects of fining treatment, storage temperature and storage time on turbidity, total polyphenol, browning index, microbiological, and sensory quality of clarified banana juice were evaluated during storage. Fining treatment, storage temperature and storage time had a significant (p<0.001) effect on turbidity, total polyphenol and browning index of clarified banana juice. Turbidity and browning index of juice were reduced by fining treatment with bentonite and a combination of gelatin and bentonite but increased with storage temperature and storage time. A significant decrease in total polyphenol content and increase in turbidity and browning index were detected for all juice samples during storage. However, it was noted that changes were significantly greater in control juice stored at higher temperature than in juice stored at 4 or 25 °C for up to 6 months. Sensory evaluation revealed that juices treated with bentonite or a combination of gelatin and bentonite and stored at 4, 25 or 37 °C were acceptable for up to six months, whereas untreated juice stored at 37 °C was only acceptable for up to 16 weeks.