Pitaya peel powder (PPP) samples passed through 595, 420, 210, or 105‐µm sieves were partially replaced with wheat flour in cookie making. The use of 10% PPP in the cookie formulation significantly increased the content of total dietary fiber, betacyanin, and total phenolics, as well as the antioxidant capacity of the product but slightly reduced its protein and starch content. When the sieve aperture for PPP decreased from 595 to 105 µm, the phenolic content of supplemented cookies increased by 19.2%, the DPPH radical scavenging activity and ferric reducing antioxidant power were enhanced by 14% and 38%, respectively, while their total fiber content was slightly reduced. The use of PPP with small particle size decreased the diameter, thickness, and volume of the cookies but enhanced their density and hardness. The cookies incorporated PPP passed through 210‐µm sieve and had similar overall sensory acceptability to that of the control cookies.
Novelty impact statement
Dietary fiber with a balanced ratio of soluble and insoluble fiber as well as bioactive compounds with high antioxidant activity is provided by PPP. The use of PPP in cookie formulation improved the fiber, phenolic, and betacyanin content of the product and its antiradical activity and ferric reducing power. The results of this work reveal that PPP is a potential antioxidant dietary fiber source for the development of new food products with high fiber and antioxidant content in the food industry.
Pitaya peel is a by-product of fruit processing. In this study, the effects of pitaya peel supplementation in the cookie recipe on the nutritional quality, in vitro glycemic index, and antioxidant release from the enriched fiber cookies were investigated. The higher the ratio of pitaya peel powder (PPP) in the recipe, the greater the dietary fiber, betacyanin and phenolic contents, and antioxidant activities of the product. Cookies supplemented with 10–25% PPP were classified as having a low glycemic index, ranging from 51.9 to 45.7 in relation to glucose reference. The release of betacyanins, phenolics, and antioxidant activities from the cookie samples was recorded at the salivary, gastric, intestinal, and colon steps during in vitro sequential digestion, and the gastric digestion showed the highest release of antioxidant content and activity. The increased PPP ratio in the cookie recipe improved the antioxidant activities of the aqueous fractions at the four digestive steps. Statement. This study has a preprint entitled “Effects of the ratio of pitaya peel powder on the product quality, predicted glycemic index, and antioxidant release during in vitro sequential digestion” (DOI: https://doi.org/10.21203/rs.3.rs-2322871/v1). This preprint was posted on the research square website on December 5th, 2022.
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