Investigating the Impact of Dragon Fruit Peel Waste on Starch Digestibility, Pasting, and Thermal Properties of Flours Used in Asia

Abstract

As a by-product of dragon fruit consumption, dragon fruit peel (DFP) was developed into powder as a natural ingredient. Nevertheless, the effect of DFP on the physicochemical properties of flours used in Asian food processing and cooking remains unknown. In this study, starch digestibility, thermal, pasting, and physicochemical properties of DFP and flours (potato, rice, glutinous rice, and wheat) were characterized. It was found that DFP contained 65.2% dietary fiber together with phenolic compounds, betacyanins, and antioxidant activity. The results demonstrated that DFP (from 125 to 500 mg) reduced starch digestibility of flours, rapidly digestible starch, and slowly digestible starch, along with an increased proportion of undigested starch. A marked increase in phenolic compounds, betacyanins, and antioxidant activity occurred when DFP and flour were incubated for 180 min under simulated gastrointestinal digestion. The results indicate that bioactive compounds in DFP were highly bioaccessible and remained intact after digestion. Moreover, DFP exerted a significantly lower gelatinization enthalpy of flours with increasing peak viscosity and setback with decreasing pasting temperature. FTIR confirmed the decreased ratio at 1047/1022 cm−1, indicating the disruption of short-range orders of starch and DFP. These findings would expand the scope of DFP food applications and provide a knowledge basis for developing DFP flour-based products.

Dragon Fruit Peel Waste (Hylocereus undatus) as a Potential Ingredient for Reducing Lipid Peroxidation, Dietary Advanced Glycation End Products, and Starch Digestibility in Cookies

“…The DFP was prepared in accordance with a previously published method [18]. Fresh dragon fruit peels were first carefully washed, and the epicarp was removed.…”

“…The powder was then stored in polyethylene foil bags at a temperature of −20 • C until further use. The characteristics of the DFP used in this study were previously described in our published research [18]. The proximate composition of DFP consisted of 70.85% carbohydrates, including 65.17% dietary fibers and 5.68% available carbohydrates.…”

“…The TBC in cookies was determined according to the method previously described by Chumroenvidhayakul et al [18]. The absorbance of the extracted cookie solution was measured at 538 nm, and the amount of TBC was calculated using a standard curve of betanin.…”

“…As a result of these benefits, dragon fruit peels are now considered a by-product with potential for use as a dietary fiber enhancer, natural colorant, and antioxidant in various food products. Interestingly, our prior investigation has established that the incorporation of dragon fruit peel powder (DFP) into various flour types led to a decline in starch digestibility, alteration of gelatinization enthalpy, and pasting properties, which were attributed to the presence of dietary fibers, phenolic compounds, and betacyanins [18]. In line with these findings, the aim of the present study was to investigate the effect of incorporating DFP into wheat cookies on starch digestibility, predicted glycemic index (pGI), and heat-induced toxicants.…”

Supplementation of pitaya peel powder to cookie formulation: Effects of ratio of pitaya peel powder on the product quality, predicted glycemic index and antioxidant release during in vitro sequential digestion

“…As a result, the spread ratio of the PPP incorporated cookies was lower than that of the control cookies. This can be explained by high water holding capacity of dietary ber [35], resulting in increased viscosity of the cookie dough and reduced spread ratio of the baked product [36]. Table 2 shows that the cookie volume tended to decrease slightly when the ratio of PPP was 25% while the cookies added with the lower ratios did not differ in volume compared to the control (p > 0.05).…”