1 H-NMR analysis, antioxidant activity, and α-amylase and α-glucosidase inhibitory potential of ten common Thai edible flowers.

BACKGROUND: Edible flowers have been used in cooking as foods as well as medicine alternatives. The objectives were to identify a major class of organic compounds in edible flowers by applying proton nuclear magnetic resonance (1 H-NMR) metabolite fingerprinting and to evaluate bioactivity including antioxidant and α-amylase and α-glucosidase inhibitory activities. RESULTS: A total of 32 metabolites including five organic acids, eight sugars, 11 amino acids and eight phenolic compounds were identified by using 1 H-NMR at 600 MHz. The aromatic proton of phenolic compounds was observed at the low-field region ranged between δ 5.5 ppm and 10.0 ppm. Total phenolic content (TPC) of the extracts of edible flowers ranged from 6.0 mg GAE g-1 dry weight (DW) to 47.97 mg GAE g-1 DW. Antioxidant activity varied from 140.5 mmol L-1 TE g-1 DW to 985.2 mmol L-1 TE g-1 DW. The extracts from edible flowers showed dose-dependent inhibition against enzyme. The extract of African marigold (Tagetes erecta L.) had the highest half maximal inhibitory concentration (IC50 ) against α-amylase at 0.13 mg mL-1 while the extract of flower of Sesban agasta (Sesbania grandiflora Desv.) had the lowest IC50 against α-amylase at 0.63 mg mL-1 . Moderate correlation was found between IC50 values against α-glucosidase and antioxidant activity values (R2  = 0.66) (P < 0.05). CONCLUSION: 1 H-NMR application provided metabolomic fingerprinting of edible flowers and the in vitro inhibitory potential activity against key enzymes related to diabetes indicated that specific edible flowers have a potential use for dietary management during the early stages of hyperglycaemia. © 2021 Society of Chemical Industry.

Quality and bioactive compounds of blends of Arabica and Robusta spray-dried coffee.

The objective of this study was to develop both a possible process and a spray-dried coffee product with a balanced content of bioactive compounds. Spray-dried coffees were prepared by mixing different ratios of medium-roasted Coffea canephora (R) with green Coffea arabica (A) beans. Overall, quality characteristics of spray-dried coffees were not different. The dominant signals of 1D 1H NMR were identified as trigonelline, caffeine and chlorogenic and organic acids. Principal component analysis explained 81.8% of the total variance. Roasted Robusta spray-dried coffee was clearly distinguished from blended coffees. Forty-two volatile compounds were identified. An increase in green Arabica mixed with roasted Robusta in the blends resulted in an increase in 5-caffeoylquinic acid but a decrease in caffeine contents. Spray-dried coffee prepared from a A35:R65 showed greater total phenolic content and antioxidant activity due to a balance in bioactive compounds. In addition, its coffee brew obtained the highest overall liking score.

Surface treatments and coatings to maintain fresh-cut mango quality in storage.

BACKGROUND: Edible coatings may extend fresh-cut fruit storage by preventing moisture loss and decreasing gas exchange. This study evaluated the effect of an antibrowning dip (calcium ascorbate, citric acid and N-acetyl-L-cysteine), followed or not with carboxymethylcellulose (CMC) or carrageenan coatings on quality of fresh-cut mangoes stored at 5 °C for up to 20 days. A fourth treatment, only used in one of four experiments, consisted of chitosan. Treatments were applied on 'Tommy Atkins', 'Kent' and 'Keitt' mangoes harvested from Homestead (FL), and on imported store-bought mangoes. RESULTS: The antibrowning dips maintained the best visual quality during storage for all cultivars, as indicated by higher b*, hue and L*. The CMC coating maintained similar visual quality, but carrageenan or chitosan decreased L* and b*. The antibrowning dip containing calcium ascorbate reduced firmness loss on cut pieces of 'Keitt', 'Kent' and store-bought mangoes. The antibrowning treatment maintained higher titratable acidity for 'Kent' and 'Keitt', resulting in lower sensory sweetness. CONCLUSION: This study with repeated experiments showed that calcium ascorbate with citric acid and N-acetyl-L-cysteine maintained cut mango slices attractiveness in storage by keeping light color in both varieties. The addition of a polysaccharide coating did not consistently improve quality.