Ultrasound-assisted extraction (UAE) is widely used; however, the efficiency of extraction depends on the raw materials. Therefore, optimization of UAE must be investigated for each type of plant material. By-products from soursop fruit have not been studied as a source of bioactive compounds. In this work, the optimization of UAE conditions (extraction time (5, 10, and 15 min), pulse cycle (0.4, 0.7, and 1 s), and sonication amplitude (40%, 70%, and 100%)) for the extraction of phenolic compounds (soluble, hydrolyzable, condensed tannins, and total polyphenols) from soursop by-products (seed, peel, and columella) and pulp was evaluated using response surface methodology. The optimal conditions for UAE to obtain the highest total polyphenol content from by-products and pulp was dependent on the raw material. Peel resulted in the highest content of total polyphenols (187.32 mg/g dry matter [DM]) followed by columella (164.14 mg/g DM), seed (36.15 mg/g DM), and pulp (33.24 mg/g DM). The yield of polyphenolic content from peel and columella obtained with UAE was higher (32–37%) than conventional extraction for 2 h under stirring (14–16%). The contents of gallic acid (0.36–15.86 µg/g DM), coumaric acid (0.07–1.37 µg/g DM), and chlorogenic acid (9.18–32.67 µg/g DM) in the different parts of the fruit were higher in the extracts obtained by UAE compared with a conventional extraction method (0.08–0.61, 0.05–0.08, 3.15–13.08 µg/g DM, respectively), although it was dependent on the raw materials. Soursop by-products can be functionally important if they are used to extract bioactive compounds by UAE; a technology with high potential for commercial extraction on a large scale.

In this study, fresh and steamed under pressure (SPP) pineapple pomace were used to produce dietary fiber concentrates (DFCs) dried by freeze-drying or hot air-drying. Chemical, physical and technological properties were determined to select one pineapple DFC (PDFC) and to evaluate its mixture effect with meats on characteristics of Vienna-type sausages. The PDFC produced from SPP and hot air-dried (SPDFC-HD) had the highest content of DF, carotenoids, polyphenols such as gallic, cinnamic and p-coumaric acids, antioxidant capacity and hydration properties. Microstructural analysis evidenced a cell wall disruption of the PDFCs matrix by the effect of processing. The cubic model equations showed that with the increase in SPDFC-HD in the ternary mixture, a reducing effect on nitrites, moisture, shear force and shrinkage was obtained in sausages, while carotenoids and antioxidant polyphenols increased. This study demonstrated that SPDFC-HD was produced with characteristics to be used as ingredient in potential functional sausages.

In this study the effect of osmotic dehydration (OD) on the air-drying kinetics of chayote (Sechium edule (Jacq.) Swartz) fruits was investigated. Fresh and osmotically dehydrated chayote parallelepipeds (1 × 1 × 2 and 4 × 4 × 2 cm) were subjected to convective drying at air temperatures of 50 and 60°C, with air velocities of 1.5 and 2.5 m/s. The OD pretreatments were performed in 10 and 25% NaCl solutions (w/w) at 25°C during 3 h using a solution-to-fruit mass ratio of 4:1. The use of higher air velocities notably accelerated drying rates as manifested through significantly higher drying rate constants estimated with Page's model, whereas no effect of temperature was observed. A previously reported analytical solution that considers both product shrinkage and variable diffusivity was generalized to describe the drying kinetics of food products with parallelepiped geometry. Selected drying experiments were then fitted to this solution using six different sets of model assumptions. Results indicated that product shrinkage is the main factor to be considered in order to estimate reliable values for diffusion coefficients. The OD pretreatments produced a significant reduction of the initial moisture content of chayote slabs before drying, thus allowing shorter drying time, which may lead to reduced energy consumption.