Development and application of rice starch based edible coating to improve the postharvest storage potential and quality of plum fruit (<i>Prunus salicina</i>)

The study investigated the possibility of enhancing the shelf life of plum fruit coated with rice starch-ι-carrageenan (RS-ι-car) composite coating blended with sucrose fatty acid esters (FAEs). Film solution (starch 3%, carrageenan 1.5% and FAEs 2%) was prepared by mixing the ingredients and properties of stand-alone films (physical, mechanical, barrier and surface morphology) were studied before applying the coating on fruit surface. Fruit were stored at 20 °C for 3 weeks and analyzed for weight loss, ethylene production, respiration rate, color change, firmness, and titratable acidity (TA) and soluble solid content (SSC). Surface morphology of stand-alone film and fruit surface (after applying on the plum fruit) was studied using scanning electron microscopy (SEM). Phytochemical analysis was performed during the storage period and total phenolic content (TPC), total antioxidant capacity (TAC), flavonoid content (FC) and free radical scavenging activity were determined. The rice starch composite coating was shown to be effective in reducing both weight loss (WL) and respiration rate and inhibiting the endogenous ethylene production when compared to the uncoated control fruit stored at room temperature (p &lt; 0.05). TPC, TAC, FC and free radical scavenging activity was unaffected in the coated fruit throughout the storage period (p &lt; 0.05). The findings reported in this study indicate that the RS-ι-car-FAEs coating prolongs the shelf life and maintains the overall quality of plum fruit during storage and could potentially be commercialized as a new edible coating for the plum fruit industry

A starch edible surface coating delays banana fruit ripening

A rice starch edible coating blended with sucrose esters was developed for controlling the postharvest physiological activity of Cavendish banana to extend postharvest quality during ripening at 20 ± 2 °C. Coating effectiveness was assessed against changes in fruit physiochemical parameters such as weight loss, titratable acidity, total soluble solids, flesh fruit firmness, ion leakage, colour change, respiration, ethylene production, chlorophyll degradation and starch conversion were determined. The topography of coating material on the fruit surface was evaluated by scanning electron microscope (SEM). Surface morphology studies highlighted the binding compatibility of the coating matrix with the fruit peel character and formed a continuous uniform layer over the fruit surface. The results showed that the coating was effective in delaying ethylene biosynthesis and reducing respiration rate. Other factors impacting included delayed chlorophyll degradation, reduced weight loss and retention of fruit firmness for the first six days, all of which improved the commercial value of the fruit. The shelf life of coated fruit was prolonged for 12 days in comparison with the untreated control which ripened within seven days and lost marketability after Day 6. The pilot study demonstrates the effectiveness of a starch-based edible coating formulation for improving the ambient storage capacity of banana fruit

Amylose-lipid complex as a measure of variations in physical, mechanical and barrier attributes of rice starch- ι -carrageenan biodegradable edible film

Improvements in the hygroscopic properties of starch based films are important to strengthen their mechanical properties. The effects of different hydrophobic components-butyric acid (BA, C4:0), lauric acid (LA, C12:0), palmitic acid (PA, C16:0), oleic acid (OA, C18:1), stearic acid (SA, C18:0) and sucrose fatty acid ester (FAEs) on the rice starch (RS)-ι-carrageenan (ι-car) composite films were investigated. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) in combination with amylose-lipid complexing index (CI) were used to characterise the changes in structure and properties of edible films. The SEM results showed that the surface of films became smoother after the incorporation of fatty acids. Carbon-chain length was a major determinant of CI formation which further influenced the attributes of RS-ι-car films. The addition of FAEs to RS-ι-car improved film thickness, permeability, transparency, tensile properties (TS) and could be used to tailor biodegradable edible films with enhanced properties and future fruit coating applications

Effect of starch physiology, gelatinization, and retrogradation on the attributes of rice starch-ι-carrageenan film

Edible films and coatings have been applied as the potential substitutes for conventional plastics in food packaging. However, their physical and mechanical properties still have limitations and thus require further improvement. In this study, we compared the physico–chemical properties of starches extracted from eight rice varieties and attempted to predict their promising effects on the physical (thickness and solubility), mechanical (tensile strength and elongation break), barrier (water vapor permeability), and optical properties (color and transparency) of rice starch-ι-carrageenan films. The results showed that starch amylose content and amylose–amylopectin associations during retrogradation play a significant role in determining various properties of the films. The film containing starch from “Reiziq” variety showed minimum thickness (0.08 mm), water vapor permeability (WVP) (2.7 gs−1 m−1 Pa−1), solubility (43.12%) opacity (0.44%), and better mechanical properties, demonstrating the importance of selection of the source of the starch. The results also indicated that rice starch had compatibility with ι-carrageenan, and the blend of these two polysaccharides can be potentially used for coating fruit and vegetables

Browning on the surface of cut lettuce slices inhibited by short term exposure to nitric oxide (NO)

Freshly cut lettuce slices (Latuca sativa L.) were fumigated with nitric oxide (NO) gas at concentrations between 5 and 1000 μl/l in air at 20 °C for 1-4 h or dipped in an aqueous solution of the NO-donor compound, 2,2'-(hydroxynitrosohydrazino)-bisethanamine (DETANO) at concentrations between 10 and 1000 mg/l for 15 s to 60 min at 20 °C. Development of browning on the cut surfaces was inhibited during subsequent storage at 0 °C. The most effective treatments for extending postharvest life of lettuce slices were fumigation with 500 μl/1 NO for 1 h, and dipping in 500 mg/l DETANO for 5 min. Dipping in DETANO solution was, however, more effective as it generated a 100% increase in postharvest life compared with a 70% increase due to NO gas. Solutions of DETANO in water were found to be relatively stable as the same extension in postharvest life was obtained for five batches of lettuce sequentially dipped in the same solution