EFFECT OF DRYING ON COLOR, PROXIMATE COMPOSITION AND DRYING KINETICS OF SLICED CHESTNUTS TERESA DELGADO 1,2 , JOSÉ ALBERTO PEREIRA 1 , SUSANA CASAL 2,3 and ELSA RAMALHOSA 1 1 Mountain Research Centre (CIMO) – School of Agriculture, Polytechnic Institute of Bragança, Campus de Sta Apolónia, Apartado 1172, Bragança 5301-855, Portugal 2 LAQV-REQUIMTE, Faculty of Pharmacy of University of Porto, Rua de Jorge Viterbo Ferreira, n.° 228, Porto 4050-313, Portugal 3 Corresponding author. TEL: +351-220428638; FAX: +351-226093390; EMAIL: sucasal@ff.up.pt Received for Publication January 6, 2015 Accepted for Publication May 14, 2015 doi:10.1111/jfpe.12244 ABSTRACT In the present work, dried sliced chestnuts (Judia and Longal varieties), product with an increased shelf life, low calorie and gluten-free contents, were prepared. The effect of air convective drying on the drying kinetics, color and proximate composition of sliced chestnuts was evaluated. Even though significant differences in nutritional composition were found between both varieties at the beginning, the drying behaviors were similar; however, Judia dried at a slightly faster rate than Longal. The use of Page, two-term, and modified Henderson and Pabis models fitted well the experimental data (adjusted R 2 > 0.999). With drying, slight variations in color were observed for both varieties and only moisture content decreased significantly. The obtained product retained all chemical composition, and due to the low caloric value (367 kcal/100 g product), low fat and gluten-free contents of chest- nut slices, this can be an interesting substitute to other high-calorie snacks avail- able in the market. PRACTICAL APPLICATIONS The chestnut fruit is increasingly popular among consumers. The fruit is usually sold fresh or frozen while smaller fruits are generally rejected by industries. So, it is very important to find alternatives to valorize these fruits. Moreover, consumers search for healthy and easy-to-consume food. Chestnut follow these requisites, being a nut with interesting properties due to its low fat content, high levels of starch (sugar of slow absorption) and significant amounts of fibers. Furthermore, it is a gluten-free nut, ideal for celiac patients. On the other hand, the majority of snacks in the market are rich in fat and are made from wheat flour. So, the devel- opment of snacks based on chestnut would be innovative. This study intends to provide information on the effect of drying on color, nutritional composition and drying kinetics of sliced chestnut in order to obtain a healthy and low-calorie content snack. INTRODUCTION Consumers’ search for healthy and easy-to-consume food is increasing. Chestnut follows these requisites, being a nut with interesting properties due to its low fat content, high levels of starch (sugar of slow absorption) and significant amounts of fibers (Borges et al. 2008). Furthermore, it is a gluten-free nut, ideal for celiac patients. On the other hand, the majority of snacks in the market are rich in fat and are made from wheat flour (that contains gluten). So, the development of snacks based on chestnut would be innovative and will allow the development of new prod- ucts to persons with sensitivity to gluten. The production of dried slices of chestnuts emerged as a possible and healthy option, with low-calorie content. Several studies on hot air drying have been performed in chestnuts, namely on drying kinetics (Moreira et al. 2005; Guiné and Fernandes 2006; Cletus and Carson 2008), Journal of Food Process Engineering ISSN 1745-4530 1 Journal of Food Process Engineering •• (2015) ••–•• © 2015 Wiley Periodicals, Inc. 512 Journal of Food Process Engineering 39 (2016) 512–520 V C 2015 Wiley Periodicals, Inc. Journal of Food Process Engineering ISSN 1745-4530