Influence of soil and soilless agricultural growing system on postharvest quality of three ready-to-use multi-leaf lettuce cultivars

In this study the influence of soil and soilless growing systems (substrate 3:1 v/v perlite:peat) on quality and microbial traits of three multi-leaf lettuce cultivars (two green, ‘Eztoril’ and ‘Ezabel’, and one red, ‘Ezra’) was evaluated at harvest and after 7 and 13 days of storage at 8°C. At harvest, ‘Ezra’ showed a respiration activity and a total phenol content respectively 2-fold and 25% significantly higher than the green cultivars. Soil lettuces resulted more stressed than those grown in soilless, as indicated by their initial content in antioxidants. As for nitrate content, soilless grown lettuces at harvest showed an average concentration higher than soil-grown ones, although values are generally lower than limits imposed by the EU Regulation (No. 1258/2011). During storage, soilless lettuces showed no ammonium accumulation, differently from those cultivated in soil. In addition, lettuce cultivars grown in soilless condition showed unchanged content in the antioxidant activity and total phenols, and lower microbial counts than soil lettuces. Results of the present study showed that soilless growing system can positively affect qualitative and microbiological parameter of lettuces studied, and it can be considered a good soilless growing technique in order to obtain high quality multi-leaf lettuces for ready-to-use industry

Automatic Identification of Relevant Colors in Non-Destructive Quality Evaluation of Fresh Salad Vegetables

Quality loss during storage is often associated to changes in relevant product colors and/or to the appearance of new pigments. Computer Vision System (CVS) for non-destructive quality evaluation often relies on human knowledge provided by operators to identify these relevant colors and their features. The approach described in this paper automatically identifies the most significant colors in unevenly colored products to evaluate their quality level. Its performance was compared with results obtained by exploiting human training. The new method improved quality evaluation and reduced the subjectivity and the inconsistency potentially induced by operators

Active packaging for table grapes: Evaluation of antimicrobial performances of packaging for shelf life of the grapes under thermal stress

Abstract The paper reports the formulation of an active packaging based on PET coated with a Layered Double Hydroxide (LDH) hosting 2-acetoxybenzoic anion (salicylate) as antimicrobial molecule. The release of the molecule anchored to the LDH, compared to the molecule free dispersed into the coating, appeared much slower. Permeability of carbon dioxide and oxygen through the packaging at different temperatures was evaluated, as well as the capability of the active material to inhibit Pseudomonas, Listeria and Lactobacillus. Table grape was stored in thermal stress conditions (i.e. 10 °C) into the active packaging and the total mesophilic aerobic count and yeasts and moulds population was evaluated up to 14 days of storage. The experimental results were used for a theoretical prediction of shelf life of the packed grapes and compared with the same fruit packed into untreated material. Global and specific migration of salicylic acid from the active packaging demonstrated, in compliance with the migration limits of the EU regulation, the suitability of the considered material for food contact

Relationship between Quality Parameters and the Overall Appearance in Lettuce during Storage

Fresh-cut and whole iceberg lettuce were stored in refrigerated condition and the main sensory (overall appearance: OA, browning index: BI), physical (colour variation: ΔE*), chemical (respiration activity: RA, ammonia content: A) and biochemical (total chlorophyll: TC, antioxidant activity: AA, total phenols: TP, o-quinones: o-q, polyphenol oxidase: PPO, phenylalanine ammonia-lyase: PAL and peroxidase: POD) traits were followed during the trial. Significant relationships among these parameters were assessed by principal component analysis (PCA) in order to find the main traits related to OA, in fresh-cut lettuce. Results from PCA showed that OA was inversely correlated with BI (r=-1.00), DE* (r= -0.98), A (r= -0.94), AA (r= -0.86), TP (r= -0.82), o-q (r= -0.89), and PAL (r= -0.80). Moreover, OA was positively related with RA (r= 1.00) and PPO activity (r= 0.96). Ammonia resulted significantly correlated with the main sensory, physical, chemical and biochemical parameters. Thus, this parameter, with DE* could be used as indicator of the product quality and acceptability in control quality procedures. In conclusion, rating scale used to estimate OA, resulted a valid method to evaluate the iceberg lettuce quality, since it showed significant relationships with the main analytical parameters

Marketability of ready-to-eat cactus pear as affected by temperature and modified atmosphere

In order to increase the diffusion of cactus pear fruits, in this study, the proper maturity index for peeling and processing them as ready-to-eat product was evaluated and characterized. Thereafter, the effects of different storage temperatures and modified atmosphere conditions on the marketability of ready-to-eat cactus pear were studied. The storage of ready-to-eat fruits at 4 °C in both passive (air) and semi-active (10 kPa O(2) and 10 kPa CO(2)) modified atmosphere improved the marketability by 30%, whereas the storage at 8 °C caused a dangerous reduction in O(2) partial pressure inside modified atmosphere packages, due to fruits’ increased metabolic activity. A very low level of initial microbial growth was detected, while a severe increase in mesophilic and psychrophilic bacteria was shown in control samples at both temperatures during storage; an inhibitory effect of modified atmosphere on microbial growth was also observed. In conclusion, modified atmosphere improved only the marketability of fruits stored at 4 °C; whereas the storage at 8 °C resulted in deleterious effects on the ready-to-eat fruits, whether stored in air or in modified atmosphere

Combined Effect of Dipping in Oxalic or in Citric Acid and Low O2 Modified Atmosphere, to Preserve the Quality of Fresh-Cut Lettuce during Storage

Leaf edge browning is the main factor affecting fresh-cut lettuce marketability. Dipping in organic acids as well as the low O2 modified atmosphere packaging (MAP), can be used as anti-browning technologies. In the present research paper, the proper oxalic acid (OA) concentration, able to reduce respiration rate of fresh-cut iceberg lettuce, and the suitable packaging materials aimed to maintaining a low O2 during storage, were selected. Moreover, the combined effect of dipping (in OA or in citric acid) and packaging in low O2 was investigated during the storage of fresh-cut iceberg lettuce for 14 days. Results showed a significant effect of 5 mM OA on respiration rate delay. In addition, polypropylene/polyamide (PP/PA) was select as the most suitable packaging material to be used in low O2 MAP. Combining OA dipping with low O2 MAP using PP/PA as material, resulted able to reduce leaf edge browning, respiration rate, weight loss and electrolyte leakage, preserving the visual quality of fresh-cut lettuce until 8 days at 8 °C

[3,3]-sigmatropic Claisen rearrangement: a rapid access to Phenylpropenes and Lignan structures.

Phenylpropenes or allylbenzenes derivatives are the skeletons of many biologically important natural products as gingerol, eugenol, chavicol, safrole and estragole (1). They are also precursors of Lignans and Stegane structures which are studied for their important activities (2). In this work we report a rapid and efficient methodology to obtain various phenylpropenes 1 performing a [3,3]-sigmatropic Claisen rearrangement of compounds 2 (3). The protected phenols could be easily prepared from substrates 3 with an allylation reaction on the corresponding free hydroxyl group. (Figure 2). With this synthetical approach we are able to synthesize the 1,2,3,4-tetramethoxy-5-(2-propenil)benzene, an antibacterical natural product (4), in only 4 steps and 58% overall yield. (1) Koeduka, T. Plant Biotechnol. 2014, 31, 401–407. (2) Chang, J.; Reiner, J.; Xie, J. Chem. Rev. 2005, 105, 4581–4609. (3) Tripathi, S.; Chan, M.-H.; Chen, C. Bioorg. Med. Chem. Lett. 2012, 22, 216–221. (4) Trikojus, V. M.; White, D. E. J. Chem. Soc. Resumed 1949, 436–439

Computational Modelling of Modified Atmosphere Packaging: Application to Cactus Pear and Truffle as Case Studies

Shelf life improvement for two different products (cactus pears and truffles), stored at 8 and 5°C respectively under modified atmosphere packaging (MAP), was assessed by modelling heat and mass transport as well as package geometry and storage conditions. An innovative approach was implemented by coupling an engineering tool, such as the computational fluid dynamics (CFD) with experimental data, such as visual quality, respiration rate, head space composition, and weight loss upon MAP storage. The overall model, incorporating all phenomenological variations, has been finally tuned-up by means of a specific multi-objective optimization. It is seen that the models are able to simulate complex, multidimensional food-package ensembles under MAP conditions. As for cactus pears, a multidimensional, transient model is proposed by combining generalized transport notations with respiration and microbial growth kinetics. As for truffles, a model able to predict the effect of storage on quality loss was obtained. The adoption of predictive and comprehensive mathematical models is an economic method to evaluate packaging and operating performance, compared to more expensive experimental methods. Computational models, such as these, can be used to verify existing MAP configurations, or to design new ones. Exploitation of this mathematical tool would allow for informed technical and management decisions