Okra pectins (OKPs) with diverse structures obtained by different extraction protocols have been used to study the relationship between their molecular structure and emulsifying properties. A targeted modification of molecular structure offers a more rigorous method for investigating the emulsifying properties of pectins. In this study, three glycoside hydrolases, polygalacturonase (PG), galactanase (GL), and arabinanase (AR), and their combinations, were used to modify the backbone and side-chains of OKP, and the relationships between the pectin structure and emulsion characteristics were examined by multivariate analysis. Enzymatic treatment significantly changed the molecular structure of OKP, as indicated by monosaccharide composition, molecular weight, and structure analysis. GL- and AR- treatments reduced side-chains, while PG-treatment increased side-chain compositions in pectin structure. We compared the performance of hydrolyzed pectins in stabilizing emulsions containing 50% v/v oil-phase and 0.25% w/v pectin. While the emulsions were stabilized by PG (93.3% stability), the emulsion stability was reduced in GL (62.5%), PG+GL+AR (37.0%), and GL+AR (34.0%) after 15-day storage. Furthermore, microscopic observation of the droplets revealed that emulsion destabilization was caused by flocculation and coalescence. Principal component analysis confirmed that neutral sugar side-chains are key for long-term emulsion stabilization and that their structure explains the emulsifying properties of OKP. Our data provide structure-function information applicable to the tailored extraction of OKP with good emulsification performance, which can be used as a natural emulsifier.

In this study, the quality characteristics of carrot jellies prepared using different gelling agents (gelatin and carrageenan) and sugar substitutes (sucrose, sorbitol, and xylitol) were evaluated. The effects of gelling agents and sugar substitutes on the pH, °Brix, color, syneresis, melting-down rate, textural properties, and sensory acceptance of the jellies were determined. Textural analysis indicated that gelatin-based jellies containing sugar substitutes sorbitol and xylitol showed higher hardness than that of gelatin-based jelly containing sucrose. Among all samples, jellies containing 1.5% (w/v) carrageenan showed higher hardness, cohesiveness, and chewiness than those of other jellies, regardless of the sugar substitute. The pH and °Brix of carrageenan-based jellies were lower than those of gelatin-based jellies. The instrumental color values of jellies containing gelatin decreased with an increase in gelatin concentration. Gelatin-based jellies (3 and 5 %) containing sucrose and gelatin-based jelly (5%) containing xylitol showed lower syneresis than that in other jellies. Jelly containing 5% gelatin content had a lower melting-down rate compared with that containing 3% gelatin content. Moreover, carrageenan-based jellies showed a lower melting-down rate than that of gelatin-based jellies Carrot jellies containing 3% gelatin and xylitol showed a high score for sensory acceptance. Based on the results, the utilization of 3% gelatin and xylitol as a sugar substitute is suitable for producing carrot jellies showing high sensory preference and stability.

Peony root is a medicinal plant containing potent bioactive compounds. This study used response surface methodology (RSM) to optimize ultrasonic-assisted extraction (UAE) conditions of antioxidant compounds from peony roots. A central composite design consisting of extraction temperature (30-70°C), ethanol concentration (20-100% v/v), and extraction time (15-55 min) was used to determine the significance of each extraction condition on the total polyphenol, paeoniflorin, and myricetin contents and 2,2¢-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)- scavenging activity of the extracts. The ABTS-scavenging activity and myricetin content increased with an increasing extraction temperature. Further, at low ethanol concentrations, paeoniflorin and myricetin contents increased. Superimposition of 4D graphs revealed that an extraction temperature of 60-65°C, ethanol concentration of 40-50%, and extraction time of 40-50 min were optimal extraction conditions for peony root. A validation experiment was conducted using 45% ethanol at 63°C for 45 min. Under these UAE conditions, the experimental values of total polyphenol, paeoniflorin, and myricetin contents, and ABTS-scavenging activity were 101.80 mg GAE/g, 46.87 mg/g, 184.30 mg/g, and 23.13%, respectively. The validation experiment revealed slight differences between the experimental and predicted values (less than 10%), confirming the optimal UAE conditions for obtaining peony root antioxidant compounds via RSM. This study provides valuable information in developing functional food, medicine, and cosmetic using peony root extracts.