Composite starch-based coatings applied to strawberries (Fragaria ananassa)

High Amylose-Based Bio Composites: Structures, Functions and Applications

As biodegradable and eco-friendly bio-resources, polysaccharides from a wide range of sources show steadily increasing interest. The increasing fossil-based production of materials are heavily associated with environmental and climate concerns, these biopolymers are addressing such concerns in important areas such as food and biomedical applications. Among polysaccharides, high amylose starch (HAS) has made major progress to marketable products due to its unique properties and enhanced nutritional values in food applications. While high amylose-maize, wheat, barley and potato are commercially available, HAS variants of other crops have been developed recently and is expected to be commercially available in the near future. This review edifies various forms and processing techniques used to produce HAS-based polymers and composites addressing their favorable properties as compared to normal starch. Low toxic and high compatibility natural plasticizers are of great concern in the processing of HAS. Further emphasis, is also given to some essential film properties such as mechanical and barrier properties for HAS-based materials. The functionality of HAS-based functionality can be improved by using different fillers as well as by modulating the inherent structures of HAS. We also identify specific opportunities for HAS-based food and biomedical fabrications aiming to produce cheaper, better, and more eco-friendly materials. We acknowledge that a multidisciplinary approach is required to achieve further improvement of HAS-based products providing entirely new types of sustainable materials.

Optimization of Gum Arabic and Starch-Based Edible Coatings with Lemongrass Oil Using Response Surface Methodology for Improving Postharvest Quality of Whole “Wonderful” Pomegranate Fruit

The effects of edible coatings based on gum arabic (GA) (0.5–1.5%), maize starch (MS) (0.5–1.5%), lemongrass oil (LO) (2–4%), and glycerol (GC) (0.5–1%) developed using response surface methodology (RSM) on “Wonderful” pomegranate fruit were studied. After 42 days of storage (5 ± 1 °C, 95 ± 2% RH) and 5 days at ambient temperature (20 ± 0.2 °C and 60 ± 10% RH), whole fruit were evaluated for weight loss (%) and pomegranate juice (PJ) for total soluble solids (°Brix), titratable acidity (% Citric acid), and antioxidant capacity. The optimization procedure was done using RSM and the response variables were mainly influenced by the concentrations of MS and GA. The optimized coating consisted of GA (0.5%), MS (0.5%), LO (3%), and GC (1.5%) with desirability of 0.614 (0—minimum and 1—maximum). The predicted values of response variables, for the coating were weight loss (%) = 5.51, TSS (°Brix) = 16.45, TA (% Citric acid) = 1.50, and antioxidant capacity (RSA = 58.13 mM AAE/mL PJ and FRAP = 40.03 mM TE/mL PJ). Therefore, the optimized coating formulation is a potential postharvest treatment for “Wonderful” pomegranate to inhibit weight loss and maintain overall quality during storage and shelf-life.

Facile Mechanochemical Approach To Synthesizing Edible Food Preservation Coatings Based On Alginate/Ascorbic Acid-Layered Double Hydroxide Bio-Nanohybrids

A bionanohybrid based on ascorbic acid-intercalated layered double hydroxides (LDHs) was synthesized using a facile and novel mechanochemical grinding technique, and its efficacy as an edible food coating is reported. Ascorbic acid-intercalated Mg-Al-LDHs (AA-LDHs) are synthesized using a green water-assisted grinding approach. The successful synthesis of the mechanochemically ground AA-LDHs was confirmed by the shifts observed in the basal peaks of the LDHs based on a powder X-ray diffraction, changes in the positions of vibrational frequencies of ascorbic acid based on Fourier Transform Infrared Spectroscopy, and significant changes in the intensity and peak positions of the core-shell bands based on X-ray photoelectron spectroscopy. The resulting nanohybrid further demonstrates thermal stability in thermogravimetric and derivative thermogravimetric analysis. Transmission electron microscopy images of the mechanochemically synthesized AA-LDHs reveal a plate-like morphology, which is a characteristic of the hydrotalcite-like structure. In a novel application, an edible coating was prepared by blending the AA-LDHs into a biocompatible alginate matrix, and the coating was developed on freshly plucked strawberries using the dip-coating method. In order to evaluate the efficacy of the coating, the total phenolic content, pH, microbial growth, weight loss, titratable acidity, and ascorbic acid content were monitored in the coated and uncoated fruits for a period of 18 days. The results reveal that the shelf life of strawberries increases from 9 days to 15 days for the nanohybrid coated fruits, suggesting the potential food preservation applications of the nanohybrid.

Edible Active Coatings Based on Pectin, Pullulan, and Chitosan Increase Quality and Shelf Life of Strawberries (Fragaria ananassa)

Edible active coatings (EACs) based on pectin, pullulan, and chitosan incorporated with sodium benzoate and potassium sorbate were employed to improve the quality and shelf life of strawberries. Fruits were washed, disinfected, coated by dipping, packed, and stored at 4 °C for 15 d. Application of EACs reduced (P < 0.05) weight loss and fruit softening and delayed alteration of color (redness) and total soluble solids content. In contrast, pH and titratable acidity were not affected (P > 0.05) throughout storage, and ascorbic acid content was maintained in pectin-EAC coated strawberries. Microbiological analyses showed that application of EACs reduced (P < 0.05) microbial growth (total aerobic counts, molds, and yeasts) on strawberries. Chitosan-EAC coated strawberries presented the best results in microbial growth assays. Sensory quality (color, flavor, texture, and acceptance) improved and decay rate decreased (P < 0.05) in pectin-EAC, pullulan-EAC, and chitosan-EAC coated strawberries. In conclusion, EACs based on polysaccharides improved the physicochemical, microbiological, and sensory characteristics, increasing the shelf life of strawberries from 6 (control) to 15 d (coated fruits).

Microstructure and characteristics of high-amylose corn starch−chitosan film as affected by composition

Edible films composed of high-amylose corn starch and chitosan were developed by casting method. The effects of the ratio of high-amylose corn starch to chitosan, concentration of glycerol and methyl cellulose on the oxygen and carbon dioxide permeation, water vapor transmission, tensile strength and percent elongation at break values of edible composite films were investigated. Film microstructure was characterized by scanning electron microscopy. The results showed that the increase of the ratio of chitosan and content of glycerol in the film forming suspensions both made the structure of films flexible, causing the decrease of tensile strength and increase of percent elongation of composite films, while showing poor water vapor barrier properties as the water vapor transmission values increased. The addition of methyl cellulose as to reinforce the structure of matrix improved the water vapor barrier properties of the edible films with the decrease of water vapor transmission from 1946 to 1668 g/(m2·24 h), as well as the mechanical properties were improved as expected, which could be attributed to the differentia of the interaction between methyl cellulose and other components in the film preparation as the concentration ranged from 2% (w/w) to 8% (w/w). Films with different compositions, resulting different microstructures, showed variance in barrier and mechanical properties.

Edible coatings influence fruit ripening, quality, and aroma biosynthesis in mango fruit

The effects of different edible coatings on mango fruit ripening and ripe fruit quality parameters including color, firmness, soluble solids concentrations, total acidity, ascorbic acid, total carotenoids, fatty acids, and aroma volatiles were investigated. Hard mature green mango (Mangifera indica L. cv. Kensigton Pride) fruits were coated with aqueous mango carnauba (1:1 v/v), Semperfresh (0.6%), Aloe vera gel (1:1, v/v), or A. vera gel (100%). Untreated fruit served as the control. Following the coating, fruits were allowed to dry at room temperature and packed in soft-board trays to ripen at 21+/-1 degrees C and 55.2+/-11.1% relative humidity until the eating soft stage. Mango carnauba was effective in retarding fruit ripening, retaining fruit firmness, and improving fruit quality attributes including levels of fatty acids and aroma volatiles. Semperfresh and A. vera gel (1:1 or 100%) slightly delayed fruit ripening but reduced fruit aroma volatile development. A. vera gel coating did not exceed the commercial mango carnauba and Semperfresh in retarding fruit ripening and improving aroma volatile biosynthesis.

Gamma-irradiation influence on the structure and properties of calcium caseinate-whey protein isolate based films. Part 1. Radiation effect on the structure of proteins gels and films

Brookfield viscosimetry, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), and measurements of the texture strength of gels formed with CaCl2 and the mechanical and barrier properties of the film were applied in studies of gel formation and structural and mechanical properties of gels and films prepared using calcium caseinate (CC)-whey protein isolate (WPI)-glycerol (1:1:1), control, and irradiated with 60Co gamma rays using a 32 kGy dose. The irradiated gels have appeared to be more "fine-stranded" as compared to the more "particulate" control gels and lead to the formation of more rigid films with improved mechanical strength and barrier properties. This results from cross-linking and the modification of protein conformations were induced by irradiation, in particular the increase in the beta-sheet and beta-strand contents. Structural modifications taking place in CC-WPI composition are related to modifications taking place separately in CC and WPI. Improvement of the properties of the films after irradiation corresponds to the increased density of the cross-linked material because no change in the porosity of the films was observed by TEM.