Effect of perforation-mediated modified atmosphere packaging on the quality and bioactive compounds of soft kale (Brassica oleracea L. convar. acephala (DC) Alef. var. sabellica L.) during storage

Reduced Fertilization to Improve Sustainable Use of Resources and Preserve Postharvest Quality of Fresh-Cut Wild Rocket (Diplotaxis tenuifolia L.) in Soil-Bound and Soilless Cultivation

Reducing fertilizer input is a goal for helping greenhouse farming to achieve higher sustainability in the production process while preserving overall crop performance and quality. Wild rocket plants were cultivated in a plastic greenhouse divided into two independent sectors, one for soil-bound (SbS) cultivation and another equipped for soilless (ScS) cultivation systems. In both SbS and ScS, the crop was subjected to treatments consisting of a high- and a low-input fertilization program (HF and LF treatment, respectively). Water use efficiency (WUE) and partial factor productivity (PFP) for nutrients (N, P, K, Ca, and Mg for ScS, and N for SbS) were measured. Rocket leaves, separated for the cultivation system and fertilization program and collected at different cuts during the growing cycle, were cold stored at 10 °C until 16 d. On each sampling day (at harvest and during storage), the sensory parameters, respiration rate, dry matter, color, electrolyte leakage, antioxidant activity, total phenols, total chlorophyll and ammonia content were evaluated. In ScS, the PFP for all nutrients supplied as fertilizers showed a significant increase with the LF treatment, with values higher than 30% recorded for N, K, and Ca. As for the postharvest performance, rocket leaves cultivated in ScS showed better qualitative traits than those cultivated in SbS, as suggested by the lower values of ammonia content and electrolyte leakage recorded at the end of storage period in samples grown in ScS. Moreover, in ScS, the data showed lower membrane damage in LF than HF rocket leaves. Finally, regarding total chlorophyll content, even if no effect of each treatment was recorded in SbS, rocket cultivated in ScS showed a better retention of this parameter by applying LF rather than HF treatment. In addition to this, a PLS model (R2 = 0.7) able to predict the cultivation system, using as a variable non-destructively measured total chlorophyll content, was implemented. Low fertilization input, both in SbS and in ScS, allowed satisfying production levels and more sustainable management of nutrients. LF treatment applied to ScS also had in positive effects on the postharvest quality of fresh-cut rocket leaves.

Application of plasma activated water for Escherichia coli decontamination and shelf-life extension of kale

The aim of this study was to examine the effectiveness of plasma activated water (PAW) for inactivating Escherichia coli and retention of key quality factors for kale. Different plasma discharge times (1, 2, 3, 4, 5 and 10 minutes) and different exposure times (2, 4, 6, 8, 10 and 15 minutes) were used to investigate the inactivation effect of E. coli spot-inoculated on kale. The influence of different exposure times on the pH, hardness and color of kale was studied post- treatment. In addition, the effects of PAW on the shelf-life of kale over 12 days of storage at 4 °C was investigated. The results showed that after the treatment of 5-PAW-8 (8 min treatment by PAW generated by 5 min plasma discharge), the population of E. coli on kale was reduced about 1.55 log CFU/g and the changes of pH, hardness and color of kale were not significant (P > 0.05). During the storage period after 5-PAW-8 treatment, the statue of hardness, weight loss, color, surface morphology and ascorbic acid were found to be better than two control groups (P < 0.05). Furthermore, no significant changes were observed in pH values, the content of total phenols and 1,1-dipheny1-2-picrylhydrazyl radical-scavenging capacity (P > 0.05). It is indicated that PAW treatment is a promising method for improving the microbiological safety and extending the shelf-life of kale.

Carboxymethyl Cellulose (CMC) Based Electrospun Composite Nanofiber Mats for Food Packaging

Cellulose is one of the most abundantly available natural polymers. Carboxymethyl cellulose (CMC) belongs to the cellulose family and has different degrees of substitution. Current research comprises the fabrication and characterization of CMC nanofibers using polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) as capping agents and carriers for sustainable food packaging applications. Recently authors successfully fabricated smooth and uniform nanofibers of stated polymers and optimized the ratios of three polymers for continuous production. However, in this research, it was further characterized for mechanical properties, surface properties, structural properties, air permeability, and chemical properties to confirm the suitability and scope of tri-component nanofibrous mats in food packaging applications. Different fruits and vegetables were packed in a plastic container and closed by nanofiber mats and by a plastic lid. All samples were observed after a specific period of time (fruits were kept for 40 days while vegetables were kept for 10 days in the controlled environment). It was observed in the results that fruits and vegetables closed by nanofiber based webs exhibited better freshness and lower accumulation of moisture as compared to that of containers with plastic lids. From the results of performed tests, it was observed that nanofiber mats possess enough mechanical, structural, and morphological properties to be used as food packaging.

Digitization of Broccoli Freshness Integrating External Color and Mass Loss

Yellowing of green vegetables due to chlorophyll decomposition is a phenomenon indicating serious deterioration of freshness, and it is evaluated by measuring color space values. In contrast, mass reduction due to water loss is a deterioration of freshness observed in all horticultural crops. Therefore, in this study, we propose a novel freshness evaluation index for green vegetables that combines the degree of greenness and mass loss. The green color retention rate was measured using a computer vision system, and the mass retention rate was measured by weighing. Linear discriminant analysis (LDA) was performed using both variables (greenness and mass) as covariates to obtain a single freshness evaluation value (first canonical variable). The correct classification of storage period length by LDA was 96%. Green color retention alone allowed for classification of storage durations between 0 day and 10 days, whereas LDA could classify storage durations between 0 day and 12 days. The novel freshness evaluation index proposed by this research, which integrates greenness and mass, has been shown to be more accurate than the conventional evaluation index that uses only greenness.

Induction of Terminal Oxidases of Electron Transport Chain in Broccoli Heads under Controlled Atmosphere Storage

Controlled atmosphere (CA) storage, that is, at low O₂ and high CO₂ concentrations, effectively extends the shelf life of horticultural products. The influence of CA storage (O₂/CO₂: 2.5%/6.0% or 2.5%/0.0%) and in normal air (both at 1 °C for 21 d) on the physicochemical (O₂ uptake, mass loss and L-ascorbate) and biological properties of broccoli (Brassica oleracea var. italica, Plenck, 1794) via amounts and activities of terminal oxidases of the electron transport chain was investigated. Mass loss, a sensitive index of freshness for broccoli heads under CA, was significantly lower under CA than under normoxia (p < 0.05). Mass loss was depressed 7 d earlier under CA, including 6.0% CO₂ than under CA without CO₂. High CO₂ effectively depressed the degradation of L-ascorbate. During storage, the activity of the alternative oxidase (AOX) was lower under CA than in normal air (p < 0.05), while the amount of cytochrome c oxidase (COX), and the AOX/COX activity ratio (based on oxygen isotope discrimination), were not affected during storage. Our results indicate that CA storage effectively retained the freshness of broccoli heads by depressing the induction of AOX. However, depression of AOX amount was not associated with CO₂ around broccoli heads.