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UV-C light is a non-thermal technology with potential application in food industries. The objective was to assess UV-C radiation effect (13.44 W/m2) on microbiological decontamination and some quality characteristics of Cantaloupe melon juice, during refrigerated storage. Juice was inoculated with Listeria innocua (non-pathogenic surrogate of L. monocytogenes) and Alicyclobacillus acidoterrestris spores (spoilage indicators) used as indicators of the UV-C treatment efficacy. Total mesophylls and yeasts and molds were also enumerated. Results demonstrated that 5 min of exposure allowed 3.7 ± 0.3 log10 cycles reduction of L. innocua, while for A. acidoterrestris, 20 min were required to decrease 4.7 ± 0.1 log10 cycles. At the end of refrigerated storage for 13 days, UV-C treated juices retained color, total phenolics content and antioxidant activity, and yeast and molds did not grow. Since UV-C process was effective on microbial inactivation and allowed juice quality maintenance, it can be considered as a promising alternative to thermal pasteurization.

Nowadays, consumers demand high-quality and fresh-like food products. In the fruit juices industry, the applied processes to guarantee safety and increase shelf life often negatively impact final product quality. Although thermal treatments are the most frequently applied processes to preserve fruit juices, heating may induce undesirable changes in sensory and nutritional characteristics. These facts prompted research on alternative and mild-non-thermal processes that assure the quality and safety of this type of liquid food. In this context, UV-C light has emerged, presenting several characteristics that make it a promising alternative to traditional processing and appropriate for liquid foods. UV-C light attributes and their application in the food industry are described in this work. Due to the recognized potential of this non-thermal technology on fruit juices, numerous researchers have been focusing on this subject. A compilation of those works is presented and discussed, emphasizing the UV-C light impact on quality/nutritional aspects and microbial inactivation in fruit juices. This critical review paper aims to be a valuable tool for finding characteristics/conditions of UV-C treatments and determine the corresponding impact on quality and safety parameters of fruit juices, opening topics for further research.

Several scientific studies point fruits as rich sources of antioxidants but mainly focus on their edible part. However, fruits wastes are abundant sources of bioactive compounds and nutrients, which are considered to be health beneficial. The main purpose was to characterise juice, pulp, peel and seeds of Piel de Sapo melon, in terms of several physicochemical characteristics (soluble solids content, titratable acidity, pH, potassium, colour and water activity), some bioactive compounds (total phenolics, vitamin C, chlorophylls and total carotenoids) and total antioxidant activity. Juice, pulp, peel and seeds represent 47, 19, 27 and 5% of melon total weight, respectively. Peel and seeds stood out by their higher concentration of total phenolics compounds and antioxidant activity when compared to edible parts. The highest potassium concentration was found in seeds. Chlorophylls were only detected in peel, while carotenoids were not detected in any part of the melon analysed. Juice and pulp contributed to 69% of vitamin C amount of the whole fruit. However, its concentration in peel was equivalent to the ones observed in juice and pulp. These results pointed out the importance of fruit wastes valorisation and the development of strategies for their re-utilisation.

The objective of this study was to evaluate the impact of ozone treatment on microbiological decontamination (intrinsic microflora and inoculated Listeria innocua) and some physicochemical characteristics and bioactive compounds of Cantaloupe melon juice, also during refrigerated storage. To determine adequate ozone exposure, the survival curve of L. innocua was previously assessed. A thermal treatment was also performed seeking comparison with ozone treatment impact. After ozone exposure, L. innocua was not detected in juice samples, while thermal pasteurization allowed a reduction of 5.2 ± 0.2 log cycles. Although ozone reduced the intrinsic microflora loads, this reduction was higher for heat-treated samples. Vitamin C was highly retained in ozone-treated juices (68%), when compared with the pasteurized ones (39%). After 13 days of storage, ozone allowed the retention of the most quality parameters analyzed and, therefore, it can be considered as a promising alternative to traditional pasteurization of Cantaloupe melon juice. Practical applications: The actual consumers' demand for high-quality food standards has launched research to alternative and milder nonthermal processes, which have gained increasing attention and importance in the fruit juice industries. Ideally, preservation and/or processing of foods should involve technologies that prevent undesirable microbial survival and minimize quality attributes changes and nutrient losses. Thermal treatments are conventionally used to attain such targets; however, the content and the biological activity of the most health-related compounds are dramatically reduced. In this context, and particularly in the beverages industries, ozone has been exploited due to its potential for inactivating spoilage and pathogenic microorganisms, while being effective in overall quality retention of the products.

Fresh-cut fruit is an important segment in fruit market due to the increasing demand for healthy/convenient foods. However, processing promotes a decrease in fruits stability with faster physiological and microbiological deteriorations. Food stability is strongly attributed to its molecular dynamics and “water availability”. Understanding changes in water location/mobility is of utmost importance, since water dynamics profoundly influences physic-chemical and microbiological quality of foods. Nuclear magnetic resonance spectroscopy (NMR) is a methodology used to study the food constituents' molecular dynamics. The aim of this study is to use NMR to evaluate changes in water mobility that occurred in fresh-cut pear tissues during storage, by measuring the transverse relaxation time ( T 2 ) parameter. Results showed the existence of three water classes in the cells after processing, with T 2 values of 10 ms, 187 ms and 3s for cellular wall, cytoplasm and vacuole, respectively. Also, the obtained results demonstrated that T 2 was affected by processing and storage. Moreover, a relationship between T 2 , microstructure and the quality parameters was established. T 2, maximum value increased with pear hardness as well as water activity. On the contrary, a decrease in total colour difference (TCD) was found with T 2 . Results demonstrate the usefulness of the application of NMR relaxometry in food studies.

Although it is known that fruit products are rich sources of natural bioactive compounds, information on the nutritional value of their waste parts is scarce. The objective was to characterize the edible (juice and pulp) and waste (peel and seeds) parts of Cantaloupe melon (Cucumis melon L. var. reticulatus) in terms of some physicochemical characteristics, bioactive compounds and total antioxidant activity. Juice, pulp, peel and seeds represent 42, 23, 25 and 7% of total weight, respectively. Juice and pulp presented identical profiles in terms of physicochemical characteristics, bioactive compounds and antioxidant activity. They contributed to the majority of the overall content of carotenoids (80%) and vitamin C (84%) in Cantaloupe. Peel and seeds had the highest concentrations of potassium, being seeds the richest portion (7.08 ± 0.16 mg/g). Seeds had also the significantly highest total phenolics concentration (229.13 ± 20.92 µg/g), antioxidant activity (653.67 ± 169.20 µg/g), and soluble solids content (11.79 ± 0.90 °Brix). Peel stood out by the presence of chlorophylls. Since waste parts of Cantaloupe melon represent around 32% of total weight, their valorization is a challenge and strategies to improve ways of re-using them should be developed.

Melon seeds are an important source of bioactive compounds, which are considered to be health beneficial. Therefore, the objective of this work was to assess the impact of gaseous ozone treatments (30 and 60 min) on melon seeds paste (nonedible part) and compare with the effect on pulp (edible part). Ozone treatments were evaluated in terms of physicochemical (color, pH, and soluble solids content) and nutritional profiles (total phenolics, total carotenoids, and total antioxidant capacity) of processed material. Results indicate that ozone has a different impact on the two fruit matrices, being seeds less affected by this preservation treatment.

Ozone treatment is a non-thermal technology with promising applications in food processing. The objective of this study was to evaluate the effect of gaseous ozone at a concentration of 7.0 ± 2.4 g/L for 30 and 60 min of exposure, on some physicochemical characteristics (soluble solids content, pH, titratable acidity and color), bioactive compounds (vitamin C, total phenolics and carotenoids) and total antioxidant activity of Cantaloupe melon juice. The effectiveness of the ozone treatments in microbial survival was also assessed using Alicyclobacillus acidoterrestris spores as target spoilers of the juice (artificially inoculated). Some quality parameters were significantly affected by ozone treatments. The most relevant alterations were observed for color, vitamin C, carotenoids and total antioxidant activity. However, total phenolics content increased significantly in ozonized juices. Even though A. acidoterrestris spores reduced 2.22 ± 0.04 log cycles after 60 min of exposure, other quality related characteristics of the juice were modified. Industrial relevance The actual consumers demand for high-quality food standards have launched research to alternative and milder non-thermal processes, which have gained increasing attention and importance in the fruit juice industries. Ideally, preservation and/or processing of foods should involve technologies that prevent undesirable microbial survival and minimize quality attributes changes and nutrient losses. Thermal treatments are conventionally used to attain such targets, however, the content and the biological activity of the most health-related compounds are dramatically reduced. In this context, and particularly for the beverages industries, ozone has been exploited due to their potential for inactivating spoilage and pathogenic microorganisms while being effective in overall quality retention of the products.

Foods are partially crystalline partially amorphous systems. Edible films are considered good models for food systems due to their interesting physical properties, quite straightforward matrices, and easy reproduction. Chitosan is a semicrystalline biopolymer, biocompatible, biodegradable, with antimicrobial activity and filmogenic properties, and it has been thoroughly used in edible films studies. The purpose of this work is to investigate the relationship between the molecular relaxation time in chitosan films, their microstructure (crystallinity) and functional properties. Analyses were carried out using data on chitosan/ glycerol films prepared with different polymer/ plasticisant concentration. In general, results demonstrate that there is a relationship between macroscopic properties and water and glycerol relaxation times. Moreover, results also show that while water is free in the matrix, glycerol is linked to the chitosan polymeric chains, decreasing intermolecular attractions and increasing free volume, thus facilitating molecular migration. Also the data analysis reveals the usefulness of NMR and molecular mobility studies in the matrix for characterisation and development of polymeric structures., Authors Joana F. Fundo and Mafalda A. C. Quintas acknowledge FCT for research grants SFRH/BD/62176/2009 and SFRH/BPD/41715/2007, respectively. The authors acknowledge the Portuguese NMR Network and Strategic Project PEst-C/CTM/LA0025/2013-14 and the support by National Funds from FCT through project PEst-OE/EQB/LA0016/2011.

Physical properties and stability are critical for delivering safe and healthy food to the consumers and thus is a theme that attracts food scientists for a long time. Recently, literature suggests that stability can be fully grasped only if food molecular dynamics and structure are taken into consideration, i.e. an appropriate understanding of the behaviour of food products requires knowledge of its composition, structure and molecular dynamics, through the three-dimensional arrangement of the various structural elements and their interactions. Food systems behaviour is strongly dependent on the water molecular dynamics. Understanding changes in location and mobility of water represents a significant step in food stability knowledge, since water "availability" profoundly influences the chemical, physical and microbiological quality of foods. Nuclear magnetic resonance has been presented as a powerful technique to investigate water dynamics and physical structures of foods through analysis of nuclear magnetisation relaxation times, because it provides information on molecular dynamics of different components in dense complex systems. The application of this technique may be very useful in predicting food systems physicochemical changes, namely texture, viscosity or water migration. This paper aims at reviewing some of the main aspects related to food physical properties and stability, and the role of water in these properties. More specifically, this paper intends to contribute to a deeper understanding of the relationship of molecular constituents-structure-function of food systems, contributing to the development of foods with improved functionality.

Food stability is a critical parameter for both consumers and producers, since it assures safety, nutritional, and sensorial quality of foodstuffs, and at the same time maximizes shelf-life. For a long time, water activity, aw, was considered a determinant parameter in food stability and physical properties. This concept was challenged with the revolutionary approach to the study of food systems using the glass transition concept. Recently, scientific research suggests that molecular mobility is a fundamental approach to fully attain food physical properties and stability. Current literature suggests that stability can only be fully grasped if molecular mobility and structure are taken into consideration; that is, an appropriate understanding of the behavior of food products requires knowledge of its composition, structure, and molecular dynamics, through the three-dimensional arrangement of the various structural elements and their interactions. Food systems are complex mixtures of water, biopolymers, low-molecular weight ingredients, and colloid particles, and the molecular mobility between these different components reflects on the stability of such systems, determining the physical state, microstructure, and composition, which impacts food characteristics. Particularly, food water content, location, and interactions with other components are critical in microbial growth, degradation reactions, and sensorial aspects. Understanding changes in water location and mobility represents a significant step in food stability knowledge, once that water availability profoundly affects chemical, physical, and microbiological quality of foods.

BACKGROUND: Orange-fleshed cantaloupe melons have intense aroma and flavor but are very perishable during storage life. Fresh-cut processing enhances ethylene-mediated quality losses. Post-cutting 1-methylcyclopene (1-MCP) application to fresh-cut cantaloupe was evaluated for its effects on quality attributes, phytochemical content and aroma volatiles. RESULTS: Fresh-cut cantaloupe (Cucumis melo var. cantalupensis ‘Fiesta’) cubes treated with 1.0 µL L−1 of 1-MCP for 24 h at 5 °C, packaged in vented plastic clamshells and stored under normal atmosphere at 5 °C for 9 days, preserved their soluble solids, total phenolics, total carotenoids and β-carotene contents, but significant softening occurred. A significant increase of non-acetate esters and a decrease of aldehydes occurred during storage. Most quality attributes of fresh-cut cantaloupe were unaffected by the treatment with 1-MCP. 1-MCP-treated fresh-cut cantaloupe accumulated higher levels of propyl acetate, 2-methylbutyl acetate, methyl butanoate, methyl 2-methyl butanoate, methyl hexanoate, 2-methylbutyl alcohol and phenethyl alcohol, and lower levels of benzyl alcohol and heptanal than untreated controls. CONCLUSION: Post-cutting treatment with 1-MCP affected nine of the flavor-important volatiles, particularly those derived from the amino acids isoleucine and phenylalanine, but had no practical effect on phytochemicals or other quality attributes. © 2012 Society of Chemical Industry

Cell rupture in fresh-cut processing allows phenolic substrates and polyphenoloxidase (PPO), previously sequestered in different organelles, to react leading to undesirable color development. However, it is not always clear how PPO activity and phenolic content relate to tissue browning. We studied the effect of pH and phenolic substrates on PPO activity and on tissue browning in fresh-cut 'Rocha' pear, to help in the development of food additives that maximize the quality of fresh-cut pear. Substrates 4-methyl catechol, caffeic acid, (+)-catechin hydrate, catechol, chlorogenic acid, dopamine hydrochloride, and pyrogallol, were prepared in citric acid-phosphate buffer at pH values ranging from 3.0 to 8.0. PPO activity was assayed by measuring the rate of increase in absorbance at 420 nm wavelength at 25°C. Pear slices were covered with the buffered phenolic solutions and color change was assessed following 30 min at room temperature. pH optima for PPO activity depended on the phenolic substrate. Activity was optimal at pH 5.0 for catechol and 4-methylcatechol; pH 6.0 for chlorogenic acid; pH 7.0 for dopamine, caffeic acid, and catechin; and pH 8.0 for pyrogallol. The highest PPO activity at every pH tested was observed when catechol was used as substrate. Discrepancies were observed between the pH dependency of PPO activity and browning. Significant correlations were obtained between PPO activity and lightness (L*) or metric-hue difference (ΔH*) over the pH range 3.0 to 8.0 except for chlorogenic acid and 4-methylcatechol. With chlorogenic acid, the main PPO substrate in 'Rocha' pear, tissue browning was higher at pH 3.0 (higher ΔH*), but PPO activity was very low at the same pH. Similarly with the other phenolic substrates, browning at pH 3.0 was higher than the corresponding PPO activity. The pH of additives for cut pear should be corrected to reduce browning potential.

Egg yolk cream is a sweet confectioned with egg yolk, sugar and water. The use of raw egg products is a potential safety hazard in its production. In this work, a safer formulation is developed by using an easier to manipulate raw material – pasteurized liquid egg. Because of previous heat treatment, pasteurized liquid egg presents different sensorial, nutritional and physical properties. These changes may alter the final product's characteristics. In this work, a study on adding pasteurized egg white (as bulking agent) to the pasteurized liquid yolk was carried out. Samples made with shell eggs and with pasteurized liquid eggs were compared in terms of physical and chemical parameters. Results allowed characterizing the properties of typical egg cream and of alternative formulations using pasteurized egg yolk and white. A new formula of egg cream was developed and its sensorial acceptance was tested against the typical formulation. PRATICAL APPLICATIONS In this article, research on substituting intact raw eggs by pasteurized ones in egg yolk cream typical production is presented. This kind of product can be used in pastry fillings and toppings, or consumed as a sweet desert and also as a basis for production of several different deserts, such as fruit and nut custards. Eggs are an extremely important ingredient for food industries because of its technological and sensorial characteristics. The use of pasteurized eggs in foods formulation is a powerful instrument to improve the product's safety. However, the product's quality attributes must be preserved. In this research, the effect of an ingredient's pasteurization in a food product's rheological properties is analyzed. Also, the importance of rheological studies in new food products development and quality control is once again demonstrated.

'Rocha' pear (Pyrus communis L.) was used as a model system to assess the effect of pH of dipping solutions on quality retention of fresh-cut fruit and its interaction with calcium additives. Pear slices were dipped for 60. s in a buffer solution at pH 3.0, 5.0 or 7.0 and stored at 4.5°C for 13 days. In other experiments, pear slices were dipped for 60. s in buffer solutions containing 250. mM of calcium ascorbate, lactate, chloride, and propionate, at pH 3.0 or 7.0, and stored at 4.5°C for 6 days. Browning and softening were more intense in slices dipped in a solution at pH 3.0 than at pH 5.0 or 7.0, but microbial growth was lower in slices treated at pH 3.0. The effect of calcium additives depended on the anion and significant interactions between the effects of calcium salt and pH were observed. Calcium ascorbate was very effective in preserving color and reducing microbial growth irrespective of pH, but enhanced pectin solubilization and tissue softening at pH 3.0. Slices treated with 250. mM calcium propionate or calcium lactate were softer and had higher electrolyte efflux when treated at pH 3.0 than at pH 7.0. Calcium lactate enhanced browning and reduced microbial growth at pH 3.0 but did not affect color or microbial counts at pH 7.0. All calcium treatments enhanced electrolyte leakage. pH of the dipping solution can affect, per se, the quality of fresh-cut fruit. The choice of calcium additives to prevent undesirable changes on visual and sensory quality of cut produce should involve pH ranges that provide the expected benefits.

Fresh-cut melon is a growing and convenient segment of melon products. Melon cultivars were not bred specifically for fresh-cut processing, and the genetic bases for fresh-cut quality are unknown. We examined the link between fresh-cut quality, cell wall changes, and genetics in three near-isogenic lines (NILs) of melon (Cucumis melo L.) and in a 'Piel de Sapo' (PS) cultivar during a 9-day storage period at 4°C. The three NILs differed in initial firmness and differences persisted throughout storage of fresh-cut melon. Juice efflux was negatively correlated with flesh firmness. The climacteric NIL SC3-5-1 was softer and had higher juice efflux than the remaining NILs of the parental line PS. Fresh-cut prepared from NILs SC7-2 and SC10-2 were firmer and generally released less juice than SC3-5-1 and PS. Chelator-soluble pectins of SC3-5-1 exhibited a marked molecular size downshift during a 6-day storage period in SC3-5-1, but no significant differences in molecular size distribution were observed in the other NILs. Apparently two different quantitative trait loci (QTL) with pleiotropic effect were affecting flesh firmness and juice efflux. One QTL located in the linkage group (LG) III increased pectin depolymerisation, which was probably associated with climacteric behavior. Another two QTLs in LG VII and X were associated with initial firmness levels.

Sucrose is probably one of the most studied molecules by food scientists, since it plays an important role as an ingredient or preserving agent in many formulations and technological processes. When sucrose is present in a product with a concentration near or greater than the saturation point—i.e. in the supercooled state—it possesses high potentialities for the food industry in areas as different as pastry industry, dairy and frozen desserts or films and coatings production. This paper presents a review on critical issues and research on highly concentrated sucrose solutions—mainly, on sucrose thermal degradation and relaxation behaviour in such solutions. The reviewed works allow identifying several issues with great potential for contributing to significant advances in Food Science and Technology., Authors are grateful for the valuable discussions with Teresa S. Brandao and Rosiane Lopes da Cunha during this research. Author M. A. C. Quintas acknowledges the financial support of her research by FCT grant SFRH/BPD/41715/2007.

BACKGROUND: Egg yolk cream is confectioned with egg yolk, sugar and water. Pasteurized liquid eggs may be used in order to increase product safety, although these samples may differ from the classic ones produced with raw eggs. The objective was to evaluate and compare the stability (physicochemical characteristics, such as texture assessment, pH and water activity, and microbiological assessment) of a classic formulation and an alternative one produced with pasteurized eggs, during storage at 6, 26, 30 and 37 °C. RESULTS: From a microbiological point of view (mesophile and psychrotrophic activity), no differences were observed in either formulations. At 6 and 26 °C, rheological behaviour of both formulations remained approximately constant. At 30 and 37 °C, differences were only detected after 20 days of storage. Texture was better retained in samples prepared with pasteurized eggs, while the classic samples showed an increase in complex viscosity. CONCLUSION: Cream storage did not require refrigeration. In terms of texture and microbial load, results obtained at 6 and 26 °C were identical. The formulations only differed in texture when stored at 30 and 37 °C and for long periods. These conclusions may allow reduction of costs related to refrigerated distribution/storage of either classic or alternative formulations. Copyright © 2008 Society of Chemical Industry

Molecular mobility is a fundamental parameter which reflects the dynamic properties of food components and contributes to food degradation reactions comprehension. Fresh-cut fruits have become an important food market segment. However, processing of fruits promotes faster its physiological deterioration, biochemical changes and microbial degradation. The purpose of this work was to use NMR methodology as a tool to evaluate fresh-cut fruit quality, during storage at refrigerated conditions. The fresh-cut melon transverse relaxation time (T2) was measured for a period of 7 days of storage at 5 °C. The relationship between the obtained values, microstructure and quality parameters was investigated. In general, results show the existence of one class of water fluidity in the system, the one present in cells after processing. T2, a measure of this fluidity, is affected by the processing and storage time. Also, it is possible to find a close relationships between T2 and quality parameters of total colour difference (TCD), firmness and aw. As T2 increases TCD also increases, while firmness and aw decrease. These results highlight the usefulness of NMR methodology application in food science., Author Joana F. Fundo acknowledges Fundacao para a Ciencia e a Tecnologia (grant SFRH/BD/62176/2009). The authors acknowledge the Portuguese NMR Network and Strategic Project PEst-C/CTM/LA0025/2013-14. This work was supported by National Funds from FCT through project PEst-OE/EQB/LA0016/2013

In this work physical-chemical properties of chitosan/ glycerol film forming solutions (FFS) and the resulting films were analysed. Solutions were prepared using different concentrations of plasticising agent (glycerol) and chitosan. Films were produced by solvent casting and equilibrated in a controlled atmosphere. FFS water activity and rheological behaviour were determined. Films water content, solubility, water vapour and oxygen permeabilities, thickness, and mechanical and thermal properties were determined. Fourier transform infrared (FTIR) spectroscopy was also used to study the chitosan/glycerol interactions. Results demonstrate that FFS chitosan concentration influenced solutions consistency coefficient and this was related with differences in films water retention and structure. Plasticiser addition led to an increase in films moisture content, solubility and water vapour permeability, water affinity and structural changes. Films thermo-mechanical properties are significantly affected by both chitosan and glycerol addition. FTIR experiments confirm these results. This work highlights the importance of glycerol and water plasticisation in films properties., This work was supported by National Funds from FCT - Fundacao para a Ciencia e a Tecnologia, through project PEst-OE/EQB/LA0016/2011.Authors Joana F. Fundo, Andrea C. Galvis-Sanchez and Mafalda A. C. Quintas acknowledge FCT for research grants SFRH/ BD / 62176 / 2009, SFRH/BPD/37890/2007 and SFRH / BPD / 41715 / 2007, respectively.

tThe effect of pH, phenolic substrates, and food additives on polyphenoloxidase (PPO) activity and ontissue browning was studied in fresh-cut ‘Rocha’ pear. Substrates 4-methylcatechol, caffeic acid, (+)-catechin hydrate, catechol, chlorogenic acid, dopamine hydrochloride, and pyrogallol, were preparedin citric acid-phosphate buffer at pHs ranging from 3.0 to 8.0. pH optima for PPO activity dependedon the phenolic substrate. Activity was optimal at pH 5.0 for catechol and 4-methylcatechol; pH 6.0 forchlorogenic acid; pH 7.0 for dopamine, caffeic acid, and catechin; and pH 8.0 for pyrogallol. Discrepancieswere observed between the pH dependency of PPO activity and browning, as assessed by objective colormeasurement. Significant correlations were obtained between enzyme activity and metric-hue difference( H*) over the pH range 3.0–8.0 for four of the eight phenolics. Chlorogenic acid, the main PPO substratein ‘Rocha’ pear, induced high tissue browning but very low PPO activity at pH 3.0–4.0. Chemical inhibitionof PPO was tested using catechol as substrate, and buffer solutions containing 250 mM Ca2+in four salts(ascorbate, chloride, lactate and propionate), 57 mM ascorbic acid, 61 mM N-acetyl-l-cysteine and 3 mM4-hexylresorcinol. PPO inhibition by additives was affected by the pH of the buffer, and was more effectivewith ascorbic acid, N-acetyl-l-cysteine and calcium ascorbate. It was concluded that inferences on tissuebrowning based on PPO activity can be misleading. Measurement of tissue color is proposed as a reliablemeans to assess the antibrowning effectiveness of additives and the pH of additives for cut pear shouldbe corrected to reduce the browning potential info:eu-repo/semantics/publishedVersion

This study was developed with the purpose to investigate the effect of polysaccharide/plasticiser concentration on the microstructure and molecular dynamics of polymeric film systems, using transmission electron microscope imaging (TEM) and nuclear magnetic resonance (NMR) techniques. Experiments were carried out in chitosan/glycerol films prepared with solutions of different composition. The films obtained after drying and equilibration were characterised in terms of composition, thickness and water activity. Results show that glycerol quantities used in film forming solutions were responsible for films composition; while polymer/total plasticiser ratio in the solution determined the thickness (and thus structure) of the films. These results were confirmed by TEM. \NMR\ allowed understanding the films molecular rearrangement. Two different behaviours for the two components analysed, water and glycerol were observed: the first is predominantly moving free in the matrix, while glycerol is mainly bounded to the chitosan chain., Authors Joana F. Fundo and Mafalda A.C. Quintas acknowledge Fundacao para a Ciencia e a Tecnologia (grants SFRH/BD/62176/2009 and SFRH/BPD/41715/2007, respectively), and Portuguese NMR Network.

Wounding increases the hydrolysis of phospholipids mediated by phospholipase D (PLD) in plant tissues. Subsequent reactions may originate flavor-related aldehydes and alcohols. Lysophosphatidylethanolamine (LPE) is a naturally occurring phospholipid capable of inhibiting phospholipase D in vitro. The effect of LPE on the quality and volatile profile of fresh-cut melon was investigated. Cantaloupe melons (Cucumis melo L. 'Fiesta') were processed into cubes, vacuum-infiltrated with 200 μg L-1 of LPE, packaged in plastic clamshells and stored at 5°C for 9 days. The activities of phospholipase D (PLD) and C (PLC), respiration and ethylene production rates, color, firmness, soluble solids content (SSC), and volatile production were measured during storage at 5°C for 9 days. LPE significantly reduced the activity of PLD and PLC one day after the treatment but the effect was transient. LPE did not affect ethylene production and had a negligible effect on the respiration rate of melon cubes. Firmness and SSC were not affected by the treatment but LPE induced a very small increase in hue angle. LPE did not affect the major classes of volatiles in melon -esters and alcohols -but reduced the accumulation of aldehydes typical of wounding after the first day of storage. In conclusion, LPE did not help in the quality retention of fresh-cut melon but had a specific inhibitory effect on aldehyde production.

Orange-fleshed cantaloupe melons have intense aroma and flavor but are very perishable during storage life. Fresh-cut processing enhances ethylene-mediated quality losses. Post-cutting 1-methylcyclopene (1-MCP) application to fresh-cut cantaloupe was evaluated for its effects on quality attributes, phytochemical content and aroma volatiles.Fresh-cut cantaloupe (Cucumis melo var. cantalupensis 'Fiesta') cubes treated with 1.0 µL L(-1) of 1-MCP for 24 h at 5 °C, packaged in vented plastic clamshells and stored under normal atmosphere at 5 °C for 9 days, preserved their soluble solids, total phenolics, total carotenoids and β-carotene contents, but significant softening occurred. A significant increase of non-acetate esters and a decrease of aldehydes occurred during storage. Most quality attributes of fresh-cut cantaloupe were unaffected by the treatment with 1-MCP. 1-MCP-treated fresh-cut cantaloupe accumulated higher levels of propyl acetate, 2-methylbutyl acetate, methyl butanoate, methyl 2-methyl butanoate, methyl hexanoate, 2-methylbutyl alcohol and phenethyl alcohol, and lower levels of benzyl alcohol and heptanal than untreated controls.Post-cutting treatment with 1-MCP affected nine of the flavor-important volatiles, particularly those derived from the amino acids isoleucine and phenylalanine, but had no practical effect on phytochemicals or other quality attributes.

Respiratory behavior of fresh-cut 'Rocha' pear suggests that optimization of O 2 concentration inside modified atmosphere packages (MAP) is of limited benefit. To test this hypothesis, packages were designed to achieve three equilibrium O 2 partial pressures. Fresh-cut 'Rocha' pear was treated with 250mM calcium ascorbate solutions buffered at pH 3.0 and pH 7.0, packaged under the three MAP conditions, and stored at 5°C for 20d. Actual O 2 levels (mean±confidence interval at 95%) during the experiment were 16.7±0.2, 1.8±0.2 and 0.25±0.04kPa with corresponding CO 2 levels of 1.3±0.1, 4.3±0.2 and 6.5±0.4kPa. Changes in quality attributes related to fruit metabolism, namely firmness, titratable acidity, pH, and soluble solids content were not affected by O 2 levels. Overall changes in water activity, levels of ascorbate, and microbial growth were also independent of O 2 levels. Oxygen partial pressure inside the packages affected browning, which was more intense at 16.7kPa O 2. Sensory analyses performed after 8d in storage confirmed that panelists perceived the differences in color but did not detect differences in firmness or taste among the samples under different O 2 levels. Browning was more intense at pH 3.0 than at pH 7.0 but the kinetics of other quality attributes were not affected by pH. No significant improvements of quality attributes dependent on the physiology of respiration of fresh-cut 'Rocha' pear can be obtained by reducing O 2 partial pressure inside the packages.