Edible Coatings to Enhance Shelf life of Fruits and Vegetables -A Mini Review

Abstract:

Recently, edible coatings or films have gained enormous importance in fruits and vegetables preservation. This review summarises edible coatings, the classification of coating materials, formulation procedures, and the benefits of active edible coating. Studies reported that edible coating or films from natural resources benefit the consumer as well as the environment. In general, edible coatings or films are a combination of polysaccharides, proteins, lipids, and plasticizers, used to enhance the functional properties and the general quality parameters of fruits and vegetables, such as texture, colour, acidity, total soluble solids, thus preventing their browning and oxidation. Casting (wet process) and extrusion (dry process) are two prominent methods used to fabricate edible thin films. General techniques for applying edible coatings are dipping, spraying, coating, panning, using a fluidized bed, and film wrapping. Active edible coatings or films are developed with herbal extracts to improve the functional properties, i.e., antioxidant and antimicrobial. Therefore, based on the literature review, future research exploration will focus on underutilized edible natural resources, along with some natural edible plasticizers used to improve the postharvest quality of fruits and vegetables without affecting their nutritional, organoleptic, and sensory attributes. The primary objective of the present review was to summarize the different types of edible coating with an infusion of herbal extracts and their application on fruits and vegetables.

Dual immunological and oxidative responses in Oreochromis niloticus fish exposed to lambda cyhalothrin and concurrently fed with Thyme powder (Thymus vulgaris L.): Stress and immune encoding gene expression

The present study was performed to explore the immunotoxicological effects of the lambda cyhalothrin (LCH) insecticide and evaluate the efficiency of Thyme powder (TP) as a fish supplement in attenuation of LCH impact on Oreochromis niloticus (O. niloticus) fish. Fish was sampled following 30-days exposure to LCH (¹/₆ LC50: 0.48 μg/L) and TP (2%) supplementation, individually or in combination. The growth performance, immune status, biochemical indices, and mRNA expression pattern changes of stress and immune-encoding genes in the liver and spleen tissues, respectively, through real-time polymerase chain reaction (RT-PCR) analysis, were evaluated. The findings showed that LCH exposure caused a significant lowering in most of the estimated variables including growth performance, hematological and immunological indices. Moreover, LCH disrupted the oxidant/antioxidant status and dysregulated the expression of stress and immune-related genes, downregulating the mRNA transcript level of Immunoglobulin M heavy chain (IgM), Interferon (IFN-γ), CXC-chemokine, and Toll-like receptors (TLR-7) in the spleen. However, mRNA expression of Myxovirus resistance (Mx) gene remained unaffected. In liver tissue, the heat shock protein (HSP-70) expression was upregulated, while that of cytochrome P450 1A (CYP 1A) was downregulated. TP (2%) supplementation elicited a significant modulation in aforementioned indices; however, their levels did not attain that of the control values. Our findings concluded that LCH affects the O. niloticus immune response through the negative transcriptional influence on genes linked to immunity and induction of oxidative injury of the immune organs. Besides, dietary TP (2%) could be a proper candidate to modulate the compromised immunity in response to LCH exposure in O. niloticus aquaculture.

The Potential Gastrointestinal Health Benefits of Thymus Vulgaris Essential Oil: A Review

In recent times, medicinal plants have received great attention worldwide due to their effective pharmacological properties and therapeutic benefits. Numerous chemical compounds extracted from various medicinal plants have manifold biological activities. Thymus vulgaris (TV) is a flowering plant with an aromatic odor that has been broadly applied in conventional medicine, food additives, and phyto-pharmaceutical preparations. It is recognized to have promising therapeutic potential for curing various types of diseases. The essential oil extracted from TV, which contains a high quantity of flavonoids, possess antioxidant and antimicrobial activities. Consequently, it could be utilized as a good source in developing novel natural antioxidants and antibiotics. This review explores some of the potential health benefits of TV essential oil (TVEO) on the gastrointestinal tract.

Antioxidant Activity of Thyme Waste Extract in O/W Emulsions

Thymus vulgaris (thyme) is an aromatic plant and its essential oil has been applied as antimicrobial and antioxidant due to the presence of phenolic compounds. However, after steam distillation, the deodorized plant material is rejected, despite the possible presence of bioactive compounds. Ethanolic thyme waste extract revealed the presence of benzoic acid, 4-hydroxybenzoic acid, ferulic acid, caffeic acid, and sinapic acid. This waste thyme extract had the capacity for preventing the formation of primary and secondary lipid oxidation products in emulsions O/W (oil in water), constituted by diverse proportions of wheat and almond oils, without interfering with the viscosity parameters, for 10 weeks, at 37 °C. The increasing proportion of almond oil (≥50%) in the emulsion increases its resistance to oxidation, which is improved with the presence of an optimal concentration of tested thyme waste extract (0.02% and 0.04%). The waste thyme extract can, therefore, be used as an antioxidant either in food or pharmaceutical emulsions O/W, replacing the synthetic antioxidants.