Potentialities of High-Pressure Homogenization to Inactivate Zygosaccharomyces bailii in Fruit Juices

ABSTRACT: This experimental work was aimed to evaluate the effects of repeated high-pressure homogenization (HPH) treatments at 100 MPa on the inactivation and regrowth of Zygosaccharomyces bailii inoculated in apricot and carrot juices. Thus, the spoilage yeast was inoculated in both the juices at level of about 5 log CFU/g and the 2 systems were treated with a lab-scale Panda homogenizer for 8 passes at 100 MPa. Microbiological and chemico-physical analyses were performed immediately after the treatment and during the juice storage at room temperature. Microbial data highlighted that yeast inactivation increased with the number of passes applied. Eight passes at 100 MPa allowed yeast inactivation higher than 2.5 log CFU/mL regardless of the juice considered. On the contrary, the juice type affected the yeast fate (growth or death) over the storage at 25 °C. In fact, Z. bailii was able to attain the spoilage threshold (6 log CFU/mL) in apricot juice, although with growth kinetics dependent of the survivor levels after HPH treatment. In carrot juice this microorganism was unable to recover over the storage in the most severely treated samples. The HPH treatment had a significant effect on apricot juice pH and viscosity, while no significant effect was observed in carrot juice. The viscosity measurements showed that the application of one pass at 100 MPa resulted in the triplication of apricot viscosity index. No further significant viscosity increase (P > 0.05) was observed increasing the number of passes at 100 MPa. Practical Application: The results obtained in the present study and the proposed technology could be exploited by the industries of the beverage sector to increase the shelf life of these kinds of products. Moreover, from a technological point of view, the increase of viscosity, following the high-pressure homogenization treatment, represents a tool to expand the product gamma without the use of gelling additives or thermal treatments, which are detrimental for the sensorial and nutritional properties of this kind of products.     

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.     

Essential Oils Against Pathogen and Spoilage Microorganisms of Fruit Juices: Use of Versatile Antimicrobial Delivery Systems

Essential oils (EO) are increasingly used as natural antimicrobial compounds, however the effect of delivery system to enhance their antimicrobial activity has not been widely studied. Limonene (0 to 10 μL/mL) was added to microbial suspensions (～10⁵ CFU/mL) of selected foodborne pathogens (Listeria monocytogenes Scott A, Salmonella enterica Typhimurium, Escherichia coli and Staphylococcus aureus), and spoilage microorganisms (Lactobacillus plantarum, Saccharomyces cerevisiae, and Candida albicans). S. aureus was found to be the most sensitive foodborne pathogen while Salmonella enterica showed continued growth under all concentrations. Stable nanoemulsions and solid lipid nanoparticles (SLN) (d ～ 170 nm) were prepared using an alkane carrier oil (n‐tetradecane and n‐eicosane, respectively). Interfacial effects and homogenous distribution of limonene in nanoemulsions improved its (8 and 12 μL/mL) antimicrobial effect against S. aureus. Higher aqueous concentrations as a result of expulsion from SLN further enhanced the antimicrobial activity pronounced at higher limonene concentrations. Therefore, our findings confirm that the emulsion‐based delivery systems are able to effectively distribute limonene inside a microbial suspension to improve its antimicrobial activity.     

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.     

射频处理八角粉杀菌工艺

利用作者所在实验室团队自主研发的射频设备探究了射频处理对八角粉的杀菌效果。结果表明,随射频(27.12 MHz)处理时间的增加,样品的温度不断增大,微生物致死率也显著增加。射频处理八角粉7 min,在最大限度保证样品质量的条件下可使样品中的微生物降低1.74 lg CFU/g。但是,RF处理样品加热的非均匀性一直是制约射频技术发展的关键问题。利用4个装有相同质量八角粉(37 g)的聚乙烯塑料袋(140 mm×100 mm)对称重叠在一起组成的模型来研究射频加热的均匀性。研究结果表明,样品内部和中心的温度明显高于表面温度,RF处理结合间歇的翻转可显著提高射频加热的均匀性。射频技术是一种很有前景的低水分活度食品新型杀菌技术。     

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.     

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).     

Control of Pathogenic and Spoilage Microorganisms in Fresh‐cut Fruits and Fruit Juices by Traditional and Alternative Natural Antimicrobials

ABSTRACT: Traditional antimicrobials have been extensively used for many years. However, consumers are currently demanding wholesome, fresh‐like, and safe foods without addition of chemically synthesized preservatives. The application of novel natural antimicrobials to assure safety of fresh‐cut fruits and unpasteurized juices while preventing quality loss is a promising alternative. The effectiveness of these natural substances added to fruit derivatives has been studied by different researchers. Antimicrobials of animal (lactoperoxidase, lysozyme, and chitosan), plant (essential oils, aldehydes, esters, herbs, and spices), and microbial origin (nisin) can be used to effectively reduce pathogenic and spoilage microorganisms in fresh‐cut fruits and fruit juices. Nevertheless, the use of these compounds at a commercial level is still limited due to several factors such as impact on sensory attributes or, in some cases, regulatory issues concerning their use. Therefore, extensive research on the effects of each antimicrobial on food sensory characteristics is still needed so that antimicrobial substances of natural origin can be regarded as feasible alternatives to synthetic ones.     

超声加工技术对果蔬汁品质影响及其作用机制研究进展

传统热加工虽然能有效灭酶和灭菌,但会对果蔬汁的色泽、营养物质及风味等品质造成严重破坏。超声技术作为一种新型的非热加工技术,能够改善果蔬汁的稳定性、安全性、感官特性和营养特性,已广泛用于果蔬汁加工的研究中;但由于受到复杂因素的影响,超声波处理也可能对果蔬汁产生不利影响。本文综述了国内外有关超声技术应用于果蔬汁加工的最新研究进展,从果蔬汁内源酶、微生物（发酵微生物、致腐和致病微生物）、理化特性和营养成分（如抗坏血酸、多酚和类胡萝卜素）等不同视角深入分析了超声波处理对它们的影响及作用机制,并总结了现阶段超声技术所存在的问题及研究趋势,为超声技术在果蔬汁加工中的应用提供一定的理论基础。     

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.     

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。     

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.     

几种超滤果蔬汁的稳定性

本文探讨了四种果蔬汁的两种孔径(50KD,150KD)聚丙烯腈膜超滤液的稳定性。结果表明:50KD的黄瓜汁和萝卜汁超滤液及两种孔径的锦橙汁超滤液杀菌后贮藏,三个月后依然保持澄清。     

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.     

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.