Quality of postharvest strawberries: comparative effect of fungal chitosan gel, nanoparticles and gel enriched with edible nanoparticle coatings

This study compared, for the first time, the postharvest conservative action of edible fungal chitosan coatings (gel, nanoparticles and gel-nanoparticle) on the physico-chemical, sensorial and microbiological characteristics of strawberries. The nanoparticles were prepared by an ionic gelation method and characterized by dynamic light scattering and scanning electron microscopy. The antioxidant (DPPH* and ABTS*) activity of the edible coatings and the antimicrobial (macrodilution method) action against phytopathogenic fungi were verified. The nanoparticles had a size of 331.1 nm and a zeta potential of + 34 mV. The gel, nanoparticles and gel+nanoparticles exhibited minimum inhibitory concentration values ranging from 4 to 5, 1.5 to 2.5 and 1.0 + 0.5 to 2.0 + 1.5 g.L−1, respectively. All the edible coatings exhibited antifungal action. All the coatings had high scavenging activity, especially the gel edible coating. The coatings, especially the gel+nanoparticles, decreased the weight loss, microbiological growth, soluble solids, maturity index and moisture loss of the strawberry and preserved the pH values, anthocyanin content, titratable acidity and sensory characteristics. Therefore, the use of chitosan edible coating containing nanoparticles can be a promising strategy to improve the post-harvest quality of strawberries.info:eu-repo/semantics/publishedVersio

Growth of Cunninghamella elegans UCP 542 and production of chitin and chitosan using yam bean medium

Microbiological processes were used for chitin and chitosan productions by Cunninghamella elegans (UCP 542) grown in a new economic culture medium. The assay was carried out to evaluate the growth of C. elegans using yam bean ( Pachyrhizus erosus L. Urban) medium, in different times of growth (24, 48, 72 and 96 hrs), incubated at 28°C in an orbital shaker at 150 rpm. The lyophilized biomass was determined by gravimetry. The polysaccharides were extracted by alkali-acid treatment, and characterized by infrared spectroscopy, titration and viscosity. C. elegans grown in the yam bean medium and produced higher yields of biomass (24.3 g/ mL) in 96 hrs. The high level was chitosan (66 mg/g), and chitin (440 mg/g) were produced at 48 and 72 hrs of growth, respectively. The polysaccharides showed degree of deacetilation and viscosimetric molecular weight as: 6.2% and 3.25 x104 g/mol for chitin, and 85% and 2.72 x 104 g/mol for chitosan, respectively. The results obtained suggest high biotechnological potential of yam bean as an economic source to produce chitin and chitosan by C. elegans. In addition, the new medium using yam bean for production of the chitin and chitosan may be used for many purposes to reduce the cost price of fermentation processes

Influence of heat treatment on the sensory and physical characteristics and carbohydrate fractions of french-fried potatoes (Solanum tuberosum L.)

AbstractThe aim of this study was to analyze the impact that heat treatment with salts and freezing processes on the sensory, instrumental, and physico-chemical characteristics of fried potatoes of the Monalisa cultivar. The potatoes were blanched in distilled water (P); sodium chloride solution (B1); calcium chloride solution (B2), and a solution with both of these salts (B3). They were then pre-cooked and frozen for 24 hours and for 30 days. After frying, sensory characteristics were analyzed (color, texture, flavor, oiliness), along with overall preference and instrumental determinations of texture, color, and oil content. Further tests were conducted on the sample with the best results in the sensory analysis (B1), along with sample P as a control, to determine granule microstructure, carbohydrate fractions, glycemic index, and glycemic load. Blanching B3, despite reducing oil absorption and providing less oiliness, obtained lesser overall preference. Freezing for 30 days increased the lightness, except for when sodium chloride was used, which intensified the color yellow. The use of sodium chloride did not interfere with the type of starch granules, nor with the formation of resistant starch; however, longer freezing time reduced the glycemic index and concentrated the dietary fiber content. All samples exhibited low glycemic index and moderate glycemic loads