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QUAFETY Special Session at 1st Food Structure Design Congress in Porto

The QUAFETY Special Session at 1st Food Structure Design Congress in Porto held at Fundação António Cupertino de Miranda, Porto, Portugal, occurred last October 17th.

The Session was opened by Manuela Pintado, from Catholic University, Portugal, with a brief but complete introduction of Quafety Project, presenting general objectives, project partners, work packages description and main disseminations activities carry out until now.

Giacomo Cocetta, from Milan University, Italy, initiated the presentations with the theme "Effects of stresses on the regulation of glucosinolates metabolism in rocket (Diplotaxis tenuifolia L.)." The glucosinolates are important health promoting compounds with proven pharmaceutical and anti-cancer properties. Among the different plant families, the Brassicaceae are particularly rich in glucosinolates. The effects of pre-harvest and postharvest stresses were studied on the transcriptome and genes related to glucosinolates metabolism. Total RNA was extracted from stressed and control plants and sequenced with a two paired-end Illumina sequencing platform. The genes involved in the glucosinolates biosynthesis, catabolism and regulation were identified from the different libraries and the changes in expression in response to different stresses were reported. From the bioinformatic analysis of transcripts a total of 181 genes involved in the glucosinolate biosynthesis and regulation were identified. According to gene expression profiles observed, it seems that postharvest treatments led to a general induction of the metabolism of indole GSLs rather than GSLs deriving from other amino acids, moreover stresses appeared to stimulate the catabolism of these compounds more than their biosynthesis. The results indicated that the glucosinolate pathways can be regulated by stress applications at both pre- and postharvest stage, enhancing nutritional values of rocket and potentially related species.

Victor Rodov, from ARO – The Volcani Center, Israel, followed Giacomo with the presentation "Composite edible coatings to preserve the quality of fresh-cut melons". Edible coatings attract interest as promising techniques for controlling food deterioration. Different approaches, blending and Layer-by-Layer electrostatic deposition (LbL) were utilized to produce composite coatings comprising amphoteric protein gelatin and cationic polysaccharide chitosan. In parallel, edible films based on these compositions were tested for mechanical, optical and spectroscopic properties. In another series of trials, the LbL approach was used for coating fresh-cut melons using oppositely charged natural polysaccharides, polyanion alginate and polycation chitosan. The effects of the composite coatings on physiological, textural and microbiological parameters of fresh-cut melons were compared with those of single-component coatings and of non-coated control. All chitosan-containing coatings effectively inhibited microbial growth typically reducing the bacterial, yeast and mold counts on the product. Both LbL coatings (gelatin-chitosan and alginate-chitosan) slowed down tissue texture degradation, so that after 14 days of storage only LbL samples maintained an appreciable firmness. All composite coatings did not obstruct fruit gas exchange and did not cause accumulation of fermented off-flavor volatiles observed in melons coated with monolayer alginate. Gelatin-chitosan LBL coating slightly reduced the produce weight loss, while neither blended formulation nor alginate-chitosan LBL coating improved this parameter. The composite coatings proved themselves helpful for extending the product shelf-life.

Natasha Spadafora, from Cardiff University, UK, presented the theme "Smelling shelf life: using volatiles to assess quality and shelf-life". Processing elicits changes in flavour (sweetness) and aroma (production of volatile organic compounds – VOCs), of critical importance to the consumer. Temperature is a critical factor and therefore cut fruit and salads are usually stored at low temperatures (around 4 °C). We are using VOC analyses to obtain markers for assessing quality and safety of fresh ready to eat salads and fruits to provide useful tools to the industry. To collect VOCs from headspace thermal desorption tubes (TD) were chosen and to analyse them after, thermal desorption on Gas Chromatography and Time of Flight Mass Spectrometry (TD-GC-TOF-MS) were used. This technique is very sensitive, allows transport of samples collected on site for lab analysis. The question is whether temperature affects VOC profiles during storage. The major volatile compounds associated with melon and rocket aroma were identified and significant changes in the overall VOC profile during storage were shown. The separation of the VOC profiles from the different temperatures indicates that VOCs may be also useful markers as indicators of the effects of these parameters on quality.

And Ana Amaro, from Catholic University, Portugal, finished QUAFETY Session with the presentation entitled "Physiological and phytochemical quality of ready-to-eat rocket leaves as affected by processing, modified atmosphere and storage temperature". Processing and storage conditions are known to affect quality of RTE rocket leaves, with package atmosphere and low temperature as key factors in quality maintenance throughout processing to consumption. In order to generate recommendations to optimize phytochemical preservation of rocket leaves during processing, a nutritional audit of the processing line of a fresh-cut vegetables enterprise was performed. Samples were collected at each step of the production flowchart of RTE rocket-leaves: at rocket leaves reception, after washing and decontamination, after centrifugation and after packaging. Furthermore, the effect of modified atmosphere and temperature conditions during storage on physiological and phytochemical quality of RTE rocket leaves was evaluated and the relative changes determined. Processing, modified atmosphere and storage temperature significantly affected respiration rate, chlorophyll content and phytochemical composition of RTE rocket leaves. The integration of these results contributes to the understanding of the effects of processing and storage conditions on overall quality of RTE vegetables and provide useful information for developing processes aimed at the modulation of nutritional quality and shelf-life extension.

Both Manuela Pintado and Natasha Spadafora introduced the 7th European Short Course on Quality and Safety of Fresh-cut Produce and invited the audience to register and participate in this event.