Effects of UV-C Light Processing on Some Quality Characteristics of Grape Juices

White and red grape juices (GJs) were subjected to ultraviolet C (UV-C) light as a non-thermal preservation technology using a coiled tube UV-C reactor with nine lamps. The effects of UV-C light on microbial (total aerobic count and yeast and mould count) and some chemical quality characteristics (total phenolics, antioxidant capacity, anthocyanin and polymeric colour, etc.) of white and red GJs were investigated. The results were compared with control (untreated) and heat-treated juice samples. Single-pass UV-C treatment (12.6 J/mL) of white and red GJs resulted in 3.51 and 3.59 log reductions in total aerobic count and, 2.71 and 2.89 log reductions in yeast and mould counts, respectively. The microbial loads of both GJs were completely eliminated after two passes through the reactor (25.2 J/mL). After UV-C and heat treatments, there were no significant changes in antioxidant capacity, total phenolics, titratable acidity, soluble solids and pH of white and red GJs (P?>?0.05). The losses in monomeric anthocyanins were 6.1% and 8.7% after UV-C treatment of 12.6 and 25.2 J/mL doses, respectively. However, anthocyanin level of red GJ was significantly affected by the heat treatment with an 11.8% loss (P?<?0.05). The percent polymeric colour of the red GJ with heat treatment was significantly higher compared to the colour with the UV-C treatment.     

Inactivation of Spoiling Yeasts of Fruit Juices by Pulsed Ultrasound

This paper reports on the use of ultrasound (US) as a suitable strategy to control the growth of spoiling yeasts in fruit juices. In a first phase, US technique was tested towards Saccharomyces cerevisiae inoculated in different juices (strawberry, orange, apple, pineapple and red-fruits): the treatment was performed by modulating the level of the power (20–60 %), the duration of the treatment (2–6 min) and the pulse (2–6 s), according to a fractional design. Then, the best treatment was applied against some other spoiling yeasts (Pichia membranifaciens, Wickerhamomyces anomalus, Zygosaccharomyces bailii, Zygosaccharomyces rouxii, Candida norvegica). Finally, a challenge test for a commercial beverage (red-fruit juice), inoculated with Z. bailii and containing a citrus extract, was conducted evaluating the effect of US on the sensory scores of the beverage. The results showed that the effect of US was mainly influenced by the power and the duration of the treatment; on the other hand, the effect of pulse was less significant and slight. The highest reduction of S. cerevisiae was found in the following combination of the design: power 60 %/time 4 min/pulse 2 s and power 60 %/time 6 min/pulse 6 s; this result was confirmed for the other spoiling yeasts. US and citrus extract could be combined to prolong the shelf life of the red-fruit juice and control the growth of Z. bailii. The two hurdles exerted a different role and acted in different times: US reduced the initial contamination, whilst citrus extract controlled the yeast within the storage.     

Microbial Inactivation and Quality of Guava and Passion Fruit Nectars Treated by UV-C Light

Freshness attributes in food products continue to be a trend of relevance to consumers. UV-C light treatment of fluid foods is a non-thermal process potentially suitable to obtain high-quality fruit nectars. This study pursued to test the effect of UV-C light treatment on indigenous microorganisms and sensory quality of two tropical fruit nectars. Guava and passion fruit nectars were treated with light at λ = 253.7 nm up to 24 and 11 J/ml, respectively, in an annular reactor. The effects of this process on microbial inactivation were assessed by aerobic mesophilic count (AMC), yeast and mould count (YMC) and by triangle tests regarding sensory quality. Microbial inactivation increased with fluence. The highest fluence decreased AMC of guava and passion fruit nectars by 0.51 and 1.36 log colony-forming units (CFU) per millilitre, respectively, and YMC of guava by 0.53 log CFU/ml. However, the sensory panel detected differences due to treatments even at the lowest fluences (15 and 6 J/ml for guava and passion fruit, respectively). This work confirms the capability of UV light to inactivate microorganisms in fluid foods, but in sensitive products such as tropical fruit nectars, sensory changes may be a drawback for practical application of the technology for producing fresh-like stable products.     

Use of High-Intensity Ultrasound to Increase the Efficiency of Imazalil in Postharvest Storage of Citrus Fruits

Imazalil (IMZ) plays a key role in the storage and marketing of Citrus fruits. It represents a very important tool in the fight against postharvest pathogens and is an efficient system for reducing economic losses due to the development of rots from Penicillium digitatum and Penicillium italicum. However, the current technologies employed to apply the fungicide by drenching, spraying, or dipping are ever much less suitable and progressive restrictions by law limit the residue level on the fruit and in the waste-water. A critical analysis of the factors affecting imazalil efficacy in postharvest preservation of Citrus fruit suggests that ultrasound could be useful to overcome these drawbacks. Data obtained confirmed a faster and deeper uptake of the fungicide in mandarins and lemons when the fruits were dipped in sonicated imazalil mixtures compared to the un-sonicated ones, allowing reduction of the dose of application and duration of the treatment. Indeed dipping for 1 min in 500 mg?L^?1 IMZ sonicated mixture produced in mandarins the same residue level of dipping for 5 min in 1,000 mg?L^?1 IMZ mixture without ultrasound. Moreover, imazalil concentration in fruit after sonication did not exceed the maximum residue limit allowed by the law. Sonication did not affect the chemical parameters, weight loss, and rind color of the fruit. No damage on the fruit surface was observed after scanning electron microscopy analyses of the rind of sonicated fruit. The data obtained open new interesting perspectives in the development of new postharvest treatment technologies for Citrus fruit.     

超高压(UHP)技术在果汁灭菌中的应用

超高压处理技术被认为食品非热杀菌技术中最有潜力和发展前途的一种处理技术。我国的食品工业发展计划中超高压杀菌技术已经被列为重点开发的技术之一,超高压前几年一直处在小型试验研究阶段,如李里特与日本国际农林水产业研究中心的辰巳英三合作,对超高压下生产的豆腐凝胶进行了多方面的研究。     

Analysis of Aliphatic Organic Acids in Commercial Fruit Juices by Capillary Electrophoresis with Indirect UV Detection: Application to Differentiation of Fruit Juices

A simple, cheap, and reliable capillary zone electrophoresis (CZE) method with indirect UV detection to determine the main organic acids in several fruit juices has been developed in this work. The parameters affecting CZE separation including the chromophore reagent (2,6-pyridinedicarboxylic acid, PDC) concentration and pH in background electrolyte (BGE), temperature, and applied voltage were studied. The analytical parameters of the method as linearity, precision, and detection and quantification limits were also investigated. The proposed method was applied to the evaluation of organic acid contents of commercial fruit juices from apple, grape, mandarin, orange, and pineapple and compared with the levels allowed by European legislation. A chemometric technique such as linear discriminant analysis (LDA) was also applied to differentiate fruit juices based on CZE data. This simple and reliable developed procedure allows a rapid control of adulteration of high-value commercial fruit juices, which constitutes an important tool for authenticity texting in food industries and regulatory agencies.     

Color Stability of Apple and Pear Juices Blended with Fruit Juices Containing Anthocyanins

Apple and pear juices blended with anthocyanin pigmented juices developed haze and color stability during commercial marketing. To determine factors contributing to these problems, juice from apple and d'Anjou pear (prepared from whole fruit) and‘Bartlett’pear (peels and cores) were blended with 5, 10, 20%‘Concord’grape,‘Bing’cherry, or red or black raspberry juice. During storage at 25°C for up to 48 wk, turbidity, polymeric color, and % color due to tannin increased, while anthocyanin concentration decreased. As % anthocyanin pigmented juice increased, turbidity and polymeric color increased and % color due to tannin decreased. Within a given base juice, turbidity was highly correlated with polymeric color (r = 0.78 to 0.97).     

莲藕复合果蔬汁配比优化方法探讨

运用Mixture D-optimal设计,以感官评价为响应值,研究了以莲藕、梨、冬瓜和苹果4种原汁的不同配比对复合果蔬汁风味等感官品质的影响,确定了莲藕复合果蔬汁最优配方为:莲藕原汁49%、梨原汁21%、冬瓜原汁10%和苹果原汁20%,成品的糖酸比为20.34。     

Use of High-Intensity Ultrasound to Improve Functional Properties of Batter Suspensions Prepared from PSE-like Chicken Breast Meat

In order to explore novel processing for modifying the functional properties of pale, soft, exudative (PSE)-like chicken breast meat, we investigated the effects of high-intensity ultrasound on the functional and rheological properties, particle size distribution, microstructure, and protein secondary structures of PSE-like meat batter suspension. Normal and PSE-like chicken breast meat batter suspensions (7.5 % meat proteins, w/w) were prepared and treated by ultrasound for either 0, 3, or 6 min (frequency 20 kHz and amplitude 60 %). Ultrasound treatment significantly increased pH, gel strength, and water holding capacity of normal and PSE-like meat gels (P?G′) and viscous (G″) modulus. After ultrasound treatment, the microstructure of heated normal and PSE-like batter samples enabled the formation of a compact and more dense gel network. Ultrasound treatment reduced the salt solubility of myosin as indicated by its intensity in SDS-PAGE. However, the particle size of ultrasound-treated normal and PSE-like batter samples was reduced and became more uniform. Moreover, ultrasound decreased the α-helical content and increased the formation β-sheet, β-turns, and unordered contents of normal and PSE-like meat proteins. These results suggest that high-intensity ultrasound may be used to modify the functionality of PSE-like meat with the potential to increase economical benefits for the poultry industry.     

Sugar Analysis of Fruit Juices: Content and Method

The sugar contents of 186 samples of 11 different juices from a nation-wide sampling were determined by the use of a total sugar analyzer (TSA), a gas-liquid chromatograph (GLC) or both. Values for total sugar ranged from <3% in most tomato juices to >15% in some lemonades on a ready-to-serve basis. Agreement between the two methods was satisfactory.     

渗透蒸馏在果汁浓缩中的应用

渗透蒸馏又称为等温膜蒸馏,是一种新型的膜分离技术,一般在常压、室温下进行操作,它能生产出既保持原有芳香成分而又高度浓缩的果汁产品,该文对渗透蒸馏过程、特点,及其在果汁浓缩中的应用作了综述。     

Alginate Texturization of Highly Acid Fruit Pulps and Juices

Apple pulp and reconstituted grapefruit juice were provided as texturized alginate gels at concentrations of 5–96%, after pH adjustment. The resulting products had appreciable mechanical integrity even at very high pulp or juice concentration. Their texture, judged by compressive strength, strain at failure, and deformability modulus was improved considerably by dipping in calcium lactate solution. The original pH of the fruit could be restored by a dip in a citric acid solution without adverse effects on texture.     

Pressure-Thermal Kinetics of Furan Formation in Selected Fruit and Vegetable Juices

Furan, a potential carcinogenic compound, can be formed in array of processed foods. The objective of this study was to conduct kinetic studies in pineapple juice and assess the interactive effects of pressure (0.1 to 600 MPa) and temperature (30 to 120 °C) on furan formation. Additional experiments were carried out in tomato, watermelon, cantaloupe, kale, and carrot juice to understand the influence of matrix and juice pH. Furan was monitored in raw (control) and processed samples by automated headspace gas chromatography mass spectrometry, and quantified by calibration curve method with d₄-furan as internal standard. The data were modeled using zero-, first-, and second-order equations. The zero-order rate constants (k _T,P ), activation energy (E _a ), and Gibbs free energy of activation (ΔG ^?) of furan formation in thermally processed (TP; 90–120 °C) pineapple juice were found to be 0.036–0.55 μg/kg/min, 98–114 kJ/mol, and 173.9–180.5 kJ/mol, respectively. Furan concentration was negligible and close to the detection limit (0.37 μg/kg) after pressure treatment (600 MPa at 30 °C) of juice samples. For similar process temperatures, the rate constants of pressure-assisted thermally processed (PATP; 600 MPa at 105 °C) pineapple juice were lower than that of TP samples. Furan formation was influenced by juice matrix and pH. On the other hand, PATP markedly suppressed furan (0.7 to 1.6 μg/kg) in these selected juices. In conclusion, furan formation increased with process temperature and treatment time, while pressure treatment at ambient temperature did not promote its production. Furan formation in TP fruit juices was also influenced by juice matrix and pH, but these were not the significant factors for PATP-treated juices.     

Direct Determination of Saccharin and Acesulfame-K in Sweeteners and Fruit Juices Powders

A simple and rapid analytical procedure for determination of saccharin (SAC) and acesulfame-K (AC-K) based on UV-vis measurements and partial least squares (PLS) was proposed. Thus, an experimental design at levels 2 and 15 mg l⁻¹ for SAC and 2 and 20 mg l⁻¹ for AC-K was applied. Because real samples usually contain SAC and AC-K combined with aspartame (ASP), this interference was also included in the model. The procedure was successfully applied for SAC and AC-K simultaneous determination in sweeteners and fruit juice powders, without any separation step to remove ASP. The results were validated by using spiked samples, and the obtained recoveries were satisfactory.     

Ultrasound and Antimicrobial Compounds: A Suitable Way to Control Fusarium oxysporum in Juices

This paper reports on the use of ultrasound, combined with either Na–benzoate or citrus extract, to inhibit Fusarium oxysporum in orange juice. In a preliminary step, spores of F. oxysporum were inoculated into distilled water and treated through an ultrasound equipment; the treatments differed for acoustic energy (the maximum power attained by the equipment was 130-W frequency, 20 kHz; the energy was reported as percentage of the maximum power, from 40% to 100%), pulse (2 and 10 s), and duration of the treatment (from 2 to 10 min).Then, the treatment was validated in orange juice, in combination with either benzoate (0–100 ppm) or citrus extract (0–1,800 ppm), using a mixture design called centroid. The most significant effects were time, as single term, and the interaction energy/time/pulse; concerning the possibility of extending juice shelf life, the use of benzoate and citrus extract controlled F. oxysporum growth in orange juice and achieved a reduction of 5 log cfu/ml for at least 14 days.     

超滤对几种果蔬汁品质的影响

探讨了２种孔径（５０ＫＤ、１５０ＫＤ）的聚丙烯腈超滤膜对４种果蔬汁（甘蓝汁、黄瓜汁、萝卜汁和锦橙汁）品质的影响。结果表明：小分子的糖、酸、矿物质及维生素Ｃ的平均透过率超过９０％,２种膜间无显著性差异;大分子的蛋白质、果胶及脂溶性维生素Ｅ的平均透过率较低,２种膜间有显著性差异。超滤后的果蔬汁基本保持了固有风味并改善了某些不良风味。     

UV-C处理对采后草莓果实品质和活性氧代谢的影响

以"凤冠"草莓为材料,研究了0,1.5,3.0和4.5 k J/m2UV-C处理对草莓果实在10℃,12 d贮藏期间果实品质、呼吸强度、内源乙烯产生、可溶性糖、己糖激酶活性(HXK)、果糖激酶活性(FRK)和抗氧化酶活性的影响。结果表明,3.0 k J/m2UV-C处理能抑制草莓果实的呼吸速率和乙烯释放量,减少可滴定酸和维生素C的损失,维持果实较好的食用品质。同时发现,3.0 k J/m2UV-C处理果实中FRK和HXK活性显著高于其余3个处理果实,维持了整个贮藏期间较高的FRK和HXK活性,促进了贮藏后期果实中果糖和葡萄糖含量的下降。此外,3.0 k J/m2UV-C处理能维持草莓果实中较高的SOD,CAT,APX和POD的活性,降低超氧阴离子和MDA的积累。这表明,适宜剂量的UV-C处理(3.0 k J/m2)能维持草莓果实采后活性氧代谢通畅,抑制膜脂过氧化反应发生,延缓果实衰老的发生;3.0 k J/m2UV-C处理可能启动采后草莓果实己糖信号传导,调控草莓果实采后花色苷的合成和积累,进而促进了果实采后转色。