Cashew apple (Anacardium occidentale) is considered as a by-product of the cashew processing industry. Efficient utilization of this material source contributes to valorization of cashew and reduces the burden of agricultural waste placed on the environment. This study investigated the effects of various blanching conditions on the total tannins, the ascorbic content and the phenolic contents of cashew apples. The three parameters including blanching temperature, blanching duration and salt concentration of the blanching solution were considered. It was found that optimal blanching conditions (heating at 70°C, NaCl concentration at 1% within 2 mins) resulted in cashew apples with vitamin C content and tannin retention rate of about 78.125% and 45% compared to those of the fresh samples, respectively. The cashew apple texture seemed to be insensitive to the heating process, however, the colors (mainly red gamuts of carotenoids) were lost during blanching.

Annona muricata Linn. (soursop) belongs to the Annonaceae family. This plant has been traditionally used for the treatment of various infectious and inflammatory diseases. In this study, the effect of storage conditions (room and cold condition) on Annona muricata nutrients was evaluated on the basis of color, vitamin C, polyphenol content and antioxidant activity (DPPH). The change in Lab* brightness (64.34 ± 4.18a, -4.61 ± 0.31a, 12.80 ± 0.57a for fresh sample) was negligible during the 10 day cooling process (66.22 ± 2.33ab, -0.58 ± 7.89a, 9.03 ± 0.85b). These criteria have not changed compared to the original sample after 2 days. The effect of room temperature on properties of Soursop was significant. After 8 and 10 days, it was impossible to quantify TAA, TPC and ABTS of the sample. The values of the two samples (8 and 10 days) at low temperatures were respectively 4.46 ± 0.35 and 3.27 ± 0.33 (TAA); 3.00 ± 0.05 and 2.64 ± 0.30 (TPC); 0.66 ± 0.01 and 0.69 ± 0.04 (free-radicals scavenging capacity). The appearance and morphology of the samples are also graphically described.

Cashew apples, a by‐product accrued during the manufacture of cashew nuts, have abundant nutritional values but are not widely utilized due to the presence of substances that cause acrid taste. In this study, we attempted the production of a dried jelly cashew apple product and optimized three main processing stages including blanching, osmotic, and drying. The results showed suitable conditions at 6 mm thickness in the blanching process. The osmotic process recorded a temperature of 35°C, within 1.5 h, the ratio of sugar syrup/ingredient 2:1 with sugar syrup 60 Bx, and the addition of 0.6% citric acid on the total weight of ingredients and 0.02% CaCl2. The drying process at 55°C within 267 min had the highest ascorbic acid content (TAA), total phenolic content (TPC), and content of tannin compounds (TTC) retention. These parameters refer to a product that has good organoleptic acceptability in terms of taste, acrid content, and a high ability to retain major nutrients. Furthermore, the product recovery efficiency is 21.45%. Jelly drying cashew apples (JDC) are formed to help take advantage of by‐products, contributing to adding value for the cashew industry.

Annona muricata Linn. (soursop) belongs to the family Annonaceae. This plant had been traditionally used for treatment of various infectious and inflammatory diseases. This study aimed to determine the effects of convection drying on the nutrient composition of the plant. Measured indicators included protein content, ash content, fat, total ascorbic acid content (TAA), total phenolic content (TPC), color and sensory level of soursop. At different temperatures of 40°C, 50° and 60°C, the evaluation criteria change significantly when supplemented with °Brix at 10%, 15% and 20%. Highest protein content achieved at 20% soluble solids concentration was 2.71 ± 0.09 and 2.68 ± 0.01 at 40 and 60°C, respectively. Most of the percentage of ash of the sample was unaffected and the change of the fat content is negligible. Moreover, TAA and TPC were found to decline after the process. About 68.62% TAA was retained when drying at 40°C (20% Brix) and the figure for TPC was 38.46% (60°C, 10% Brix). Typically, in the L* color space, all samples exhibited the value of higher than than 55 and there is a tendency to give a white color. In addition, the a* and b* values increased after drying. Optimal parameters are selected based on the commercial nature of the product and the retention of nutritional value. Final results consisted of the addition of 10% syrup sugar (60 ° Brix) in the sample under the temperature of 40 ° C for 390 minutes.

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Lowering manufacturing costs and utilization of by-products are urgent requirements to improve the competitiveness of Vietnamese cashew nuts in the world market. Heat treatment strategies such as drying are common techniques to process waste sources into a food source. The degradation of polyphenol, vitamin C, and tannins in the process represent a major obstacle in maintaining the nutritional quality of cashew pulp as well as in de-acridization of raw materials. This work firstly attempted to determine the optimal convection drying conditions that gave the highest nutritional quality contents in cashew apples. Then, the polyphenol degradation kinetic of cashew apple material during the drying process was examined in zero-order and first-order kinetic models. The results suggested the best contents of polyphenol, vitamin C and tannin could be attained at the drying process at 55°C for 275 mins. In addition, the first-order kinetic model was used to describe the decomposition of polyphenols during the drying process and the equation to predict the residual polyphenol content in cashew apple was formed to optimize the process. Research parameters provide a database for the following processing processes in the production of cashew-derived food products.