Effect of a multifunctional edible coating based on cassava starch on the shelf life of Andean blackberry

Trends in maintaining postharvest freshness and quality of Rubus berries

Blackberries and raspberries, commonly known as Rubus berries, are commercially grown worldwide across different climates. Rubus berries contain wide array of phytochemicals, vitamins, dietary fibers, minerals, and unsaturated fatty acids. Nevertheless, these berries have short storage life which is the major constraint in their supply chains leading to higher postharvest losses. Inappropriate harvest handling, physical bruising, insect pests, and postharvest diseases lower the acceptability of fruit among consumers and other supply chain stakeholders. Additionally, the susceptibility to microbial decay, fruit softening, higher ethylene production, respiratory activity, and increased oxidation of anthocyanins, phenolics, and flavonoids considerably affects the marketability of Rubus berries at domestic and international markets. To date, several postharvest strategies such as cold storage, precooling, modified and controlled atmospheres, anti-ripening chemicals, edible coatings, biological agents, and nonchemical alternatives (heat treatment, ultrasound, irradiations, ozone) have been reported to prolong storage life, ensure food safety, and maintain the nutritional quality of Rubus berries. This review briefly encompasses multiple aspects including harvest maturity indices, regulation of fruit ripening, pre and postharvest factors affecting fruit quality, and an update on postharvest quality preservation by employing postharvest technologies to extend the storage life and maintaining the bioactive compounds in Rubus berries which are lacking in the literature. Accordingly, this review provides valuable information to the industry stakeholders and scientists offering relevant solutions, limitations in the application of certain technologies at commercial scale, highlighting research gaps, and paving the way forward for future investigations.

Shelf-Life Prediction and Critical Value of Quality Index of Sichuan Sauerkraut Based on Kinetic Model and Principal Component Analysis

Kinetic models and accelerated shelf-life testing were employed to estimate the shelf-life of Sichuan sauerkraut. The texture, color, total acid, microbe, near-infrared analysis, volatile components, taste, and sensory evaluation of Sichuan sauerkraut stored at 25, 35, and 45 °C were determined. Principal component analysis (PCA) and Fisher discriminant analysis (FDA) were used to analyze the e-tongue data. According to the above analysis, Sichuan sauerkraut with different storage times can be divided into three types: completely acceptable period, acceptable period, and unacceptable period. The model was found to be useful to determine the critical values of various quality indicators. Furthermore, the zero-order kinetic reaction model (R², 0.8699-0.9895) was fitted better than the first-order kinetic reaction model. The Arrhenius model (E_a value was 47.23-72.09 kJ/mol, k_ref value was 1.076 × 10⁶-9.220 × 10¹⁰ d^-1) exhibited a higher fitting degree than the Eyring model. Based on the analysis of physical properties, the shelf-life of Sichuan sauerkraut was more accurately predicted by the combination of the zero-order kinetic reaction model and the Arrhenius model, while the error back propagation artificial neural network (BP-ANN) model could better predict the chemical properties. It is a better choice for dealers and consumers to judge the shelf life and edibility of food by shelf-life model.

Delayed Senescence and Marketability Index Preservation of Blackberry Fruit by Preharvest Application of Chitosan and Salicylic Acid

Blackberry fruits are appreciated as a source of nutrients and compounds related to benefit human health. However, they are highly perishable and very susceptible to decay factors. Current methods to improve and maintain blackberry quality are limited in use because of the fruit's fragile physical properties. Regarding these properties, it has been reported that the activities of certain enzymes are linked to senescence and fruit softening processes. This study was aimed to assess the effect of salicylic acid (SA) and chitosan (COS) as preharvest treatments on the physiology related to improving fruit conservation and preserving the marketability index of blackberry fruit. The preharvest treatments were foliar sprayed on blackberry plants at different concentrations. The activities of enzymes superoxide dismutase (SOD), catalase (CAT), phenylalanine ammonia-lyase (PAL), and polygalacturonase (PG) were measured. Total soluble solids (TSS), titratable acidity (TA), TSS/TA ratio, and marketability index (MI) were analyzed after 144 h of storage. The application of 3 mM of SA and 0.25% of COS treatments preserved the MI of blackberries by reducing leakage, red drupelet reversion (RDR), and mycelium presence in the fruit. SA application increased SOD, CAT, and PAL activities. Our results also showed that SA and COS preharvest treatments modified the activity of the cell wall degrading enzyme PG, which might play a role in improving the shelf life and resistance to decay factors of blackberry fruit without any significant effects on physicochemical properties like TSS, TA, and the TSS/TA ratio.

Bioactive Edible Films and Coatings Based in Gums and Starch: Phenolic Enrichment and Foods Application

Edible films and coatings allow preserving fresh and processed food, maintaining quality, preventing microbial contamination and/or oxidation reactions and increasing the shelf life of food products. The structural matrix of edible films and coatings is mainly constituted by proteins, lipids or polysaccharides. However, it is possible to increase the bioactive potential of these polymeric matrices by adding phenolic compounds obtained from plant extracts. Phenolic compounds are known to possess several biological properties such as antioxidant and antimicrobial properties. Incorporating phenolic compounds enriched plant extracts in edible films and coatings contribute to preventing food spoilage/deterioration and the extension of shelf life. This review is focused on edible films and coatings based on gums and starch. Special attention is given to bioactive edible films and coatings incorporating plant extracts enriched in phenolic compounds.

Phenolic profiles and their responses to pre- and post-harvest factors in small fruits: a review

The consumption of small fruits has increased in recent years. Besides their appealing flavor, the commercial success of small fruits has been partially attributed to their high contents of phenolic compounds with multiple health benefits. The phenolic profiles and contents in small fruits vary based on the genetic background, climate, growing conditions, and post-harvest handling techniques. In this review, we critically compare the profiles and contents of phenolics such as anthocyanins, flavonols, flavan-3-ols, and phenolic acids that have been reported in bilberries, blackberries, blueberries, cranberries, black and red currants, raspberries, and strawberries during fruit development and post-harvest storage. This review offers researchers and breeders a general guideline for the improvement of phenolic composition in small fruits while considering the critical factors that affect berry phenolics from cultivation to harvest and to final consumption.

Effect of PLA Active Packaging Containing Monoterpene-Cyclodextrin Complexes on Berries Preservation

Blackberries and raspberries are highly perishable and fragile products, which limits their shelf life. The effect of biodegradable active packaging of blackberries and raspberries containing 2.5% and 5.0% weight (wt%) of thymol or carvacrol complexed in β-cyclodextrins (β-CDs), successively added to poly (lactic acid) (PLA), and melt-processed by injection molding was evaluated under stored conditions at 4 °C for 21 days, using as reference commercial clamshell and PLA package control samples. Thus, physicochemical, headspace, microbiological, and sensory quality studies were carried out in order to compare the efficacy of the different packages. Concerning weight loss, color, and total phenolic and soluble solids content, significant differences were detected when compared with commercial clamshell packaging. The results show that the PLA packages containing thymol and carvacrol complexes maintained the color, weight, and phenolic content of berries until day 21, with a score up to 45% better compared to commercial clamshell. The headspace analysis detected 101 mg L⁻¹ (ppm) of thymol and 35 ppm of carvacrol on the first day of refrigeration; these concentrations decreased with time. This release mechanism of carvacrol and thymol into the PLA package modified the initial atmosphere composition. After 21 days of storage, the berries had 4.25 degrees of acceptance, without adverse perception of aroma or flavor for both carvacrol and thymol compounds. A general microbial inhibition was observed for yeast and molds, which increased with the concentration of monoterpene in PLA packages, and showed an inhibition of 3.5 log units for PLA packages containing thymol, and of 3 log units for those containing carvacrol. Overall results show that PLA/β-CD-thymol 5.0% packages prolonged raspberries’ and blackberries’ shelf life by one more week at 4 °C, compared with commercial clamshell packaging.