Profiles of carotenoids during post-climacteric ripening of some important cultivars of banana and development of a dry product from a high carotenoid yielding variety

CRISPR/Cas9 based genome editing of Phytoene desaturase (PDS) gene in chilli pepper (Capsicum annuum L.)

An effective CRISPR/Cas9 reagent delivery system has been developed in a commercially significant crop, the chilli pepper using a construct harboring two distinct gRNAs targeting exons 14 and 15 of the Phytoene desaturase (CaPDS) gene, whose loss-of-function mutation causes a photo-bleaching phenotype and impairs the biosynthesis of carotenoids. The construct carrying two sgRNAs was observed to create visible albino phenotypes in cotyledons regenerating on a medium containing 80 mg/L kanamycin, and plants regenerated therefrom after biolistic-mediated transfer of CRISPR/Cas9 reagents into chilli pepper cells. Analysis of CRISPR/Cas9 genome-editing events, including kanamycin screening of mutants and assessing homozygosity using the T7 endonuclease assay (T7E1), revealed 62.5 % of transformed plants exhibited successful editing at the target region and displayed both albino and mosaic phenotypes. Interestingly, the sequence analysis showed that insertions and substitutions were present in all the plant lines in the targeted CaPDS region. The detected mutations were mostly 12- to 24-bp deletions that disrupted the exon-intron junction, along with base substitutions and the insertion of 1-bp at the protospacer adjacent motif (PAM) region of the target site. The reduction in essential photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoid) in knockout chilli pepper lines provided further evidence that the CaPDS gene had been functionally disrupted. In this present study, we report that the biolistic delivery of CRISPR/Cas9 reagents into chilli peppers is very effective and produces multiple mutation events in a short span of time.

Effect of cellulose and gum derivatives on physicochemical, microstructural and prebiotic properties of foam-mat dried red banana powder

Fruit sugars are gaining attention for their nutraceutical benefits. High sugar in ripe and over-ripe bananas makes them difficult for convective drying. In this study, red banana (RB) pulp was added with different gum derivatives as foaming agent (FA) (4 % w/w) viz., acacia gum(GA), carrageenan (CG) and gelatine(GE). Maltodextrin and carboxymethyl-cellulose were added as foam-stabilizers (FS). FA addition resulted in low density foam (RBGE-50 % reduction) with improved foam stability (RBGA-94.42 %). Powders were low in hygroscopicity (RBGA-18.62 g 100 g ^-1) with optimum flowability. The particle size (54.95 to 69.86 μm) of RB powder increased with gum derivatives addition. Secondary metabolites varied significantly in powder samples. Positive correlation of secondary metabolites with DPPH assay was observed. RBGA showed higher prebiotic activity (0.68) and supported the growth of tested Lactobacillus strain. Therefore, foam-mat dried RB powder with GA could be used in food formulation as low-cost alternative fruit sugar with higher nutritional, functional and prebiotic properties.

Study of color kinetics of banana (Musa cavendish) under microwave drying by application of image analysis

Microwave drying works on the volumetric heating concept promoted by electromagnetic radiation at 0.915 or 2.450 GHz. In this study, banana (Musa Cavendish) was taken as the sample and treated under microwave drying. The effect of two process variables, namely slice thickness (2, 3.5, and 5 mm) and microwave power (180 W, 360 W, and 540 W), were studied on drying kinetics and color kinetics. It was observed that the inverse variation relationship exists between drying time and microwave power level while drying time and slice thickness exhibited a direct variation relationship. A Computer Vision System (CVS) was developed to measure the color values of banana in CIELab space using an algorithm written in MATLAB software. Once the color parameters were obtained, they were fitted in First and Zero-order kinetic models. Both models were found to describe the color values adequately. This study concludes that microwave drying is a promising dehydration technique for banana drying that reduces the significant time of drying. Application of CVS is an excellent approach to measure the surface color of banana.

Effect of enzymatic pretreatment on the physical quality of plantain (Musa ssp., group AAB) employing airflow reversal drying

This work aimed to evaluate the effect of enzymatic pretreatment on the color and texture of plantain (Musa ssp., group AAB) dried by airflow reversal drying. Plantain slices 1.0 cm thick were used. Pretreatment with two commercial enzymes, Pectinex Ultra SPL (Aspergillus aculeatus) and Pectinex 3XL (Aspergillus niger), was performed. Drying kinetics were determined with and without pretreatment at temperatures of 50, 65 and 80 °C using a fixed bed convective dryer. An air speed of 6 m/s, a bed height of 5 cm and either unidirectional flow or airflow reversal (every 15 min) were used for drying. Color and texture were analyzed, and consumer acceptance of the results of the best treatments was determined. Pretreatment with the enzyme A. niger and airflow reversal gave the best drying kinetics and showed the greatest reduction in drying time (59.0%) at 80 °C. The best hardness results were found at 80 °C with A. niger enzymatic pretreatment with both types of air flow. Brightness and hue angle showed that samples pretreated with enzymes and dried at 65 °C had a lighter yellow color compared to non-pretreated samples. Plantain samples enzymatically pretreated and dried at 65 and 80 °C were the most accepted by consumers. This kind of enzymatic pretreatment on plantain could allow the conservation of some physical properties and reduction of drying times relative to the current methodology.