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Food safety is one of the major issues related to fresh fruit and vegetables. The preservation of the 'freshness' quality of these products is relevant due to their economical impact. This chapter is a comprehensive review of the use of essential oils from different sources and their constituents on the control of postharvest decay and overall quality preservation of fresh fruit and vegetables. An overview on the most significant postharvest diseases and their impact, as well as on the mainly used synthetic chemicals and their side-effects has been included. Emphasis has been on the sources of essential oils and their constituents studied up to now, and their effects on controlling postharvest diseases, either in vitro or in vivo, and their effect on overall quality and storage life of fresh commodities. Issues regarding their impact on human health and the environment have also been analysed.

We investigated the role of metabolite transporters in cold acclimation by comparing the responses of wild-type (WT) Arabidopsis thaliana (Heynh.) with that of transgenic plants over-expressing sucrose-phosphate synthase (SPSox) or with that of antisense repression of cytosolic fructose-1,6-bisphosphatase (FBPas). Plants were grown at 23 ∞ C and then shifted to 5 ∞ C. We compared the leaves shifted to 5 ∞ C for 3 and 10 d with new leaves that developed at 5 ∞ C with control leaves on plants at 23 ∞ C. At 23 ∞ C, ectopic expression of SPS resulted in 30% more carbon being fixed per day and an increase in sucrose export from source leaves. This increase in fixation and export was supported by increased expression of the plastidic triose-phosphate transporter AtTPT and, to a lesser extent, the high-affinity Suc transporter AtSUC1. The improved photosynthetic performance of the SPSox plants was maintained after they were shifted to 5 ∞ C and this was associated with further increases in AtSUC1 expression but with a strong repression of AtTPT mRNA abundance. Similar responses were shown by WT plants during acclimation to low temperature and this response was attenuated in the low sucrose producing FBPas plants. These data suggest that a key element in recovering flux through carbohydrate metabolism in the cold is to control the partitioning of metabolites between the chloroplast and the cytosol, and Arabidopsis modulates the expression of AtTPT to maintain balanced carbon flow. Arabidopsis also up-regulates the expression of AtSUC1, and to lesser extent AtSUC2, as down-stream components facilitate sucrose transport in leaves that develop at low temperatures.

Consumption of minimally processed fruit and vegetables has increased significantly in the past few years due to the consumers' life style. The aim of this study was to evaluate the effect of treatment with ascorbic acid or calcium chloride on the quality parameters of fresh-cut kiwifruit prepared from fruit previously stored for 3 months, either treated or not treated with 1-methylcyclopropene (1-MCP) before storage. Harvested fruit were treated with 1 microL L(-1) 1-MCP for 20 h at room temperature ( approximately 20 degrees C) (MCP) or had no treatment (C) and were then stored at 0 degrees C. After 3 months, fruit were removed from storage, peeled, and cut longitudinally in quarters, dipped in 2% ascorbic acid (Asc), 2% calcium chloride (Ca), or just water (cont), and kept at 2 degrees C for 8 days. Measurements of firmness, soluble solids content (SSC) ( degrees Brix), color (CIE L*, a*, b*), electrolyte leakage, sugars, organic acids, total phenolics, and antioxidant activity (DPPH and ABTS) were performed at 0, 4, and 8 days. A taste panel was performed on the seventh shelf life day. It was shown that whole MCP-treated kiwifruit kept better than the control through the 3 months storage, this effect being lost through the fresh-cut shelf life period. Furthermore, the postcut dip on 2% CaCl(2) was effective on delaying softening and browning of fresh-cut kiwifruit, which were also the fruit preferred by panelists. Both ascorbic acid and CaCl(2) were effective on preserving or improving nutritional properties (phenolics, ascorbic acid, DPPH, and ABTS) mainly in the first 4 days of shelf life. The CaCl(2) had a further beneficial effect until 8 shelf life days. It is suggested that CaCl(2) is better in keeping overall quality through 8 days of shelf life at 2 degrees C in fresh-cut kiwifruit followed by Asc, and 1-MCP has negligible effect in the conditions of this experiment.

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Fresh fruit and vegetables consumption has increased in the past few years due to the enhanced awareness of consumers for healthy food. However, these products are highly perishable, and losses can be of great significance if postharvest correct management is not provided. Fresh-cut products are of increasing importance, since they are presented to the consumer in a state that allows for direct and immediate consumption. However, those products are even more perishable since cutting can induce a series of senescence associated responses to wounding, and are more susceptible to microbial spoilage. Edible coatings, which intend to reduce ripening processes and protect the fruit from water loss and spoilage may be a good way to enhance the shelf life of these products. More recently, the inclusion of additives into these edible coatings to increase their effectiveness, such as essential oils and their constituents with antimicrobial and antioxidant activities, has been reported and patented.

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