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The drying of sweet potatoes not only helps to prolong its storage life but the dried form reportedly enriched with high bioactive compounds than regular sweet potatoes. The study aims to investigate the influence of dual-frequency ultrasound pretreatments (40 and 60 kHz) at two different hot air drying temperatures (70 °C and 80 °C) on quality of dried product. Ultrasound pretreatment at 40 kHz with 70 °C maintained the phytochemical compounds in the dried sweet potatoes. Ellagic acid and chlorogenic acid were found as predominant phenolic acids using HPLC analysis, while identification of two new bioactive compounds quercetin-3-rhamnoside and quercetin 3-β-D-glucoside were the novel finding of the current study. A short new band appeared in FTIR in all treatments from 2164 to 2041 cm−1 which refers to C = C alkenes functional group. The multivariate analysis showed a great influence of USH3 and USH1 with a positive relationship with most of bioactive compounds. [ABSTRACT FROM AUTHOR]

This study aimed to determine the feasibility of producing polyphenol (PPP) and pectin powders (PPE) from Georgia-grown pomegranate peels and to develop microencapsulated PPP (MPPP) powders. PPP and PPE were solvents extracted and characterized. Suspensions containing deionized water, 3 g/100 mL of PPP, and 15 g/100 mL of a blend of maltodextrin (MD):PPE of weight ratios (0:1, 3:1, 4:1, 5:1, and 1:0 g:g) were prepared and spray-dried at 140 °C inlet air temperature to produce MPPP powders. PPE had a degree of methyl esterification of 53.67%. The total polyphenol (mg GAE/mL), α-punicalagin (mg/g, dry basis, d.b.), β-punicalagin (mg/g d.b.), ellagic acid (mg/g, d.b.) content of PPP was 522.82, 108.3, 101.0, and 73.8, respectively. MPPP powders produced with higher amounts of PPE had significantly (p < 0.05) higher moisture and particle agglomeration than the rest of the powders. While MPPP powders prepared with a blend of MD:PPE had significantly (p < 0.05) higher encapsulation efficiencies (EE) (>89.90%), water solubilities (>88.09%), and antioxidant activities than the powders microencapsulated with only MD or PPE. MPPP powders produced with MD:PPE (ratio 4:1) showed the highest antioxidant activity, EE, and the particle sizes. MPPP powders with larger particles were positively correlated with higher antioxidant activities. MPPP powders may be used as novel food ingredients. [Display omitted] • High methoxyl pectin powders (PPE) were developed from pomegranate peels. • Polyphenol powders (PPP) were produced from Georgia-grown pomegranate peels. • PPP with α- and β-punicalagin and polyphenols had elevated antioxidant activities. • Microencapsulated PPP (MPPP) powders were produced with PPE and maltodextrin (MD). • MPPP powders produced with MD:PPE (ratio 4:1) had the highest antioxidant activity. [ABSTRACT FROM AUTHOR]