Bergamot: A source of natural antioxidants for functionalized fruit juices

Bergamot is a common Italian citrus fruit, cultivated almost exclusively to produce essential oils; the juice is considered a waste product, which represents a serious environmental and economic problem for the industries. The aim of this study was to re-evaluate bergamot juice through its chemical characterization and its use to enrich and fortify fruit juices. To investigate this, apples and apricots were used for the laboratory-scale production of fruit juice, following both the traditional industrial recipe and those with the addition of bergamot juice at 10% or 20%, together with or in order to replace the synthetic additives normally used in the industrial process (ascorbic acid and citric acid). The ascorbic acid content and the antioxidant activity were measured during the different steps of juice production and after storage at 37 °C for 15 days to evaluate juice shelf-life. Apricot and apple juices fortified with bergamot juice showed a significant increase in their antioxidant properties and a decreased reduction in ascorbic acid content after the typical production steps. All of the results obtained support the hypothesis that the addition of bergamot juice to juices preserves their ascorbic acid content from thermal degradation and contributes to enhance the antioxidant activity, ensuring a product much richer in antioxidants and ascorbic acid. A preliminary consumer test encouraged the production of bergamot fortified fruit juices. Finally, this is the first time that isorhoifolin and rutin have been detected in bergamot juice.     

CHANGES IN QUALITY ATTRIBUTES OF LONGAN JUICE DURING STORAGE IN RELATION TO EFFECTS OF THERMAL PROCESSING

Longan juice is accepted gradually by consumers due to its unique succulent, sweet and aromatic flavor. The effects of thermal processing (91C, 20 min) on quality related attributes (color, translucency, total soluble solids, total acidity, reducing sugars, ascorbic acid, phenolic compounds, protein and pectin) of longan juice during storage at low temperature were investigated. The heat-treated longan juice had a higher translucency and lower concentrations of pectin, phenolic compounds and proteins of longan juice, compared with the nonheat-treated juice. Furthermore, the thermal processing maintained higher concentrations of total soluble solids and total acidity but a lower ascorbic acid concentration. However, the thermal processing had no significant effects on reducing sugar concentration. Overall, the thermal processing maintained effectively color appearance and nutritional attributes such as total soluble solids and total acidity of longan juice during storage at low temperature. These results suggest that the thermal processing exhibits a potential for quality maintenance of longan juice.

PRACTICAL APPLICATIONS

Browning and turbidity are the major factor to influence quality of fruit juice during storage. Thermal processing is generally applied to improve quality and extend shelf life of fruit-related products. In this study, application of thermal processing exhibited potential for quality maintenance of longan juice in terms of evaluations of color, translucency and concentrations of total soluble solids, total acidity, reducing sugars, ascorbic acid, phenolic compounds, protein and pectin. The information obtained from this study could be used as a guideline for designing thermal processing to control the quality of longan juice.     

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.     

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。     

STUDIES ON PRESERVATION OF SUGARCANE JUICE

ABSTRACT

The variety CoP 92226 was selected for preparing sugarcane juice beverage on the basis of yield and sensory attributes from eight promising varieties of sugarcane. Sugarcane juice beverage samples were prepared by pasteurizing the sugarcane juice at 70°C for 10 minutes and adding citric acid (40 mg/100 ml), ascorbic acid (40 mg/100 ml) and potassium metabisulphite (150 ppm). Samples of sugarcane juice beverage were stored at room (30±5°C) and refrigeration (4±2°C) temperature in pre-sterilized glass bottles and analyzed for physico-chemical, microbiological and sensory attributes at every 15 days interval for 90 days. The pH, total soluble solids and total sugars decreased, whereas, titratable acidity and reducing sugars increased significantly (P<0.01) during storage. An appreciable increase in total plate counts and yeast and mold counts were observed, however, no coliforms, were detected in sugarcane juice beverage during storage. The changes in different attributes were significantly (P<0.01) higher at room temperature as compared to refrigeration temperature. The sugarcane juice beverage having citric acid and potassium metabisulphite showed minimum changes in sensory qualities during storage, both at room and refrigeration temperature. An acceptable quality beverage of sugarcane juice with satisfactory storage stability for 90 days at room as well as refrigeration temperature could be prepared.     

Efficacy of different chemicals on shelf life extension of parsley stored at two temperatures

Four different chemical treatments, GA₃, 1‐MCP, essential oils and nano‐Cu, were applied immediately after harvest to Petroselinum crispum (Mill) plants. The efficacy of the above chemicals on shelf life extension of parsley stored at 5 °C and 20 °C was determined by analysing physiological and biochemical factors that determine quality standards of storage fresh parsley. Nonsprayed parsley revealed the highest loss of weight, ascorbic acid, pigments and an enhancement of CO₂ production and lipid peroxidation at 5 °C and 20 °C of storage. Nano‐Cu was more effective for delaying weight loss and revealed a better storage capacity. GA₃, 1‐MCP and essential oils sprays were more effective in ascorbic acid retention at 20 °C than at 5 °C, whereas all substances protect samples from lipid peroxidation. Essential oils were more clearly inhibitory towards both total viable counts and yeast infection. Our results suggest that GA₃, 1‐MCP, essential oils and Nano‐Cu exert their function through different mechanisms during ripening and could provide an effective and complementary means for maintaining high‐quality parsley leaves after harvest.     

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.     

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.     

EFFECT OF SOLUBLE SOLIDS AND TEMPERATURE ON ASCORBIC ACID DEGRADATION IN LEMON JUICE STORED IN GLASS BOTTLES

Lemon juice at concentrations of 9°, 20°, 30°, 40° and 50°Brix was stored at 10°, 20° and 36°C for 16 weeks and sampled regularly for total soluble solids (TSS), pH, titratable acidity and ascorbic acid. No significant differences were found in the first two of these factors as a function of storage time. There was a small but significant decrease in citric acid concentration over 16 weeks. Ascorbic acid loss was greater at higher temperatures; at a constant temperature, the loss was smaller as TSS increased. Ascorbic acid degradation data fitted zero-, first- and second-order models equally well at all five TSS. Rate constants in 9°Brix juice were significantly higher than those for the other four concentrations at all three temperatures. E_a values of 47.8 and 24.1 kJ mol^?1 were calculated for ascorbic acid degradation in 9° and 20°Brix juices. The effect of temperature far outweighed the effect of TSS on ascorbic acid degradation. Over the 16-week storage period, maximum retention of ascorbic acid (95.7%) was obtained in the 50°Brix lemon juice concentrate stored at 10°C.     

蓝莓果汁贮藏中非酶褐变影响因素评价

为研究蓝莓果汁贮藏中非酶褐变影响因素,本文通过构建三种不同蓝莓汁体系,并分别置于4、25和37 ℃下贮藏,以褐变指数(BI)、总酚、抗坏血酸和5-羟甲基糠醛(5-Hydroxymethylfurfural,5-HMF)相关指标的变化对蓝莓汁非酶褐变进行评价,探究贮藏阶段褐变机理。结果表明,贮藏时间的增加和温度的升高加剧了蓝莓汁非酶褐变,其中总酚变化对非酶褐变影响较小;同时以5-HMF含量为主要指标,利用相减法得出抗坏血酸氧化分解反应是蓝莓汁非酶促褐变的主要因素,其次是美拉德反应,而焦糖化反应对非酶促褐变没有显著影响。可知蓝莓果汁贮藏过程中贮藏温度愈高,抗坏血酸非酶褐变速率越快,因而从某种水平上抑制5-HMF的生成来提高蓝莓汁在贮藏过程中的品质有很大的意义。     

Physio-chemical behavior of γ-irradiated garlic bulbs under ambient storage conditions

The present study was undertaken to study the effect of different gamma irradiation doses on storage life of garlic bulbs under ambient storage conditions. Garlic bulbs (cv. PG-18) were irradiated with gamma rays in dose range of 0–0.2 kGy and stored under ambient conditions (Temp 27–35 °C and RH 34–76%). Physical and chemical quality parameters i.e. physiological loss in weight (plw), rotting, sprouting, total soluble solids, firmness, ascorbic acid and allicin content of garlic bulbs was determined fortnightly to assess its storage life. On 195th day of ambient storage, the weight loss of bulbs ranged from 32.22 to 38.48% in all irradiation doses. It was observed that upto 30 days and 150 days, there was no rotting and sprouting, respectively in all the treatments. Firmness, total soluble solids, ascorbic acid and allicin content were significantly different with storage period and irradiation dose levels. It is concluded that garlic bulbs irradiated @ 0.12 kGy of gamma radiation resulted in minimum post-harvest losses along with maintaining their marketable shelf life for 4 months under ambient storage conditions.     

Effect of Initial Dissolved Oxygen Levels on the Degradation of Ascorbic Acid and the Browning of Lemon Juice during Storage

The effect of different initial dissolved oxygen concentrations (0.41, 1.44, and 3.74 mg/L) on rate of deteriorative quality changes [ascorbic acid degradation, browning, hydroxymethylfurfural (HMF) and furfural production) in lemon juice stored at 36°C was investigated. No significant effects on rate of ascorbic acid degradation and furfural formation could be attributed to the different oxygen levels. Degradation of ascorbic acid appeared to be predominantly anaerobic. Lag period before browning increased depended on oxygen level. Zero-, first- and second-order kinetic models were fitted to various degradative reactions occurring in lemon juice during storage. Highly significant correlations were obtained between browning index, HMF, and furfural formation, suggesting that all three would be suitable as chemical indices of storage temperature abuse in lemon juices.     

融安金桔不同生长期果实品质特性比较

以广西融安特产油皮金桔和脆皮金桔果实为对象,研究金桔果实在不同生长时期的理化性状及其活性成分的动态变化规律。结果表明,从9月到12月,金桔的单果重、出汁率、pH值、可溶性固形物和糖酸比等理化指标均上升,果籽率和可滴定酸含量下降;主要糖含量分别从39.04和32.38 mg/g上升至111.23和137.11 mg/g;主要有机酸为抗坏血酸、苹果酸和草酸,其中抗坏血酸含量先上升后下降,10月份为金桔抗坏血酸含量高峰期(分别为48.23和23.20mg/g),而苹果酸和草酸含量一直下降;与9月份相比,12月份的油皮和滑皮金桔总黄酮含量分别从3.45和2.14 mg RE/g下降至1.21和0.76 mg RE/g,其中特征性黄酮金柑苷含量显著上升;总酚含量和抗氧化活性均显著下降。两个品种之间,成熟单果重、可滴定酸、总黄酮和橙皮苷含量无显著差异,油皮金桔的果籽率、抗坏血酸、金桔苷和总酚含量以及总抗氧化能力均显著高于脆皮金桔,而其出汁率、p H值、可溶性固形物、糖酸比、果糖、葡萄糖、蔗糖、苹果酸、草酸和芦丁含量均显著低于后者。本研究明确了两种金桔不同生长期的果实品质特性,为金桔果实的开发和利用提供了理论依据。     

酶解对植物乳杆菌发酵红枣汁品质的影响

为了明晰酶解处理对发酵红枣汁品质的影响,采用果胶酶和半纤维素酶酶解红枣浆,研究经植物乳杆菌发酵后及4℃贮藏期间乳酸菌活菌数、主要营养品质和色泽的变化。结果表明,与对照相比,酶解处理可显著提高红枣汁的可溶性固形物含量和可滴定酸含量。酶解处理有利于保持红枣汁贮藏期间的抗坏血酸含量、多酚含量和蛋白质含量,在贮藏28d时,其含量分别高出对照0.7、0.28mg/100mL和0.58mg/100mL,多糖含量也有小幅增加,色泽有明显改善。此外,酶解处理提高了红枣汁中的乳酸菌活菌数,在贮藏28d时,酶解处理组的乳酸菌活菌数显著高出对照组0.17(lg(CFU/mL))。表明红枣汁发酵前采取酶解处理可以改善红枣汁的后续发酵品质。     

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.     

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.     

Preservation of quinces by the combination of an edible coating material, Semperfresh, ascorbic acid and cold storage

Quinces (Cydonia oblonga, Miller) have a crucial economic value owing to their demand as jams or compote, and their high vitamin and fiber content. A preservation method for extending the shelf life of quinces by the combination of an edible coating material, Semperfresh, ascorbic acid and cold storage was designed in this study. The ascorbic acid content, firmness, total sugar, pH, titratable acidity, respiration rate, soluble solids, weight, total humidity, mold, yeast, and total mesophilic aerobic bacteria count were monitored. It was found that the triple combination of Semperfresh, ascorbic acid and cold storage provides high microbial, chemical and sensorial qualities for the quinces, leading to an extension in shelf life when compared with untreated quinces.     

Kinetics of Ascorbic Acid Loss and Nonenzymatic Browning in Orange Juice Serum: Experimental Rate Constants

The kinetics of ascorbic acid loss and nonenzymatic browning in clarified orange juice (serum) were investigated in an anaerobic environment from 70.3 to 97.6°C and from 11.7 to 80.6Brix. Data were fitted to firstorder kinetic models. Rate constants of ascorbic acid degradation in serum were not different from rate constants in whole juice. Activation energies were ±30 kcal/mol and largely independent of solids concentration. Rate constants of browning pigment formation were 30–50% greater in serum. Activation energies were 19–25 kcal/mol and increased slightly with solids concentration.     

不同乳酸菌复配发酵石榴汁的品质指标分析

以石榴汁为原料,添加复配的乳酸菌进行发酵,测定发酵过程中的DPPH自由基清除率、花色苷、抗坏血酸、总酚、pH、可溶性固形物(TSS)和可滴定酸(TA)等理化指标,运用主成分分析法(PCA)对各项指标进行分析,建立发酵石榴汁的综合评价模型,并应用该模型对发酵期间的石榴汁品质变化规律进行评价。结果表明:乳酸菌复配发酵对石榴汁品质有不同程度的保持作用,植物乳杆菌和嗜酸乳杆菌复配能使石榴汁的可溶性固形物降到4.63%,可滴定酸含量增加到0.88 mg/mL,使发酵石榴汁的总酚、抗坏血酸、花色苷和DPPH自由基清除率分别达到75.9 mg/100 mL、0.066 mg/mL、42.38 mg/L和66.43%,可有效保持石榴汁的品质,适用于石榴汁发酵。     

Preparation and storage stability of juices from different carrot species

Carrot juice was prepared from each of yellow-, orange-, and purple-coloured carrots. Juice preparation included sorting, washing, peeling, acid-blanching, chopping, juicing, sterilization, and bottling steps. Bottled juices were stored in incubators which were kept at 5 °C, 20 °C, and 27 °C. Analytical determinations of pH, total soluble solids, maximum absorbance, reducing sugar, ascorbic acid, and β-carotene were made in suitable time intervals. Each of the three types of carrot juice kept at 27 °C deteriorated organoleptically in the first two weeks of storage. Juices stored at 20 °C and 5 °C were stable up to seven and twelve weeks, respectively. It was concluded that each of the carrot species can well be used for the preparation of carrot juice.