Kinetics of drying and quality of the apple cultivars Granny Smith, Idared and Jonagold

Abstract

Apple is nutritionally valuable and present as fresh fruit in human nutrition throughout the year. Also apple is a raw material in food processing, primarily in the production of juices, nectars, refreshing soft drinks, marmalades, jams, compotes, apple cider vinegar and dried fruits. In the last decade on the world market there is a great interest in dried apple products (commercially called apple chips). During preservation by drying the technological process aimed at the final product of optimal quality is required. The subject of this paper is the kinetics of the apple cv. Granny Smith, cv. Idared and cv. Jonagold drying in laboratory dehydrator for the purpose of pinpointing at which level of humidity the maximum speed of evaporation is achieved and at which level of humidity apple slices begin to change in colour and geometric shape. Parameters of the drying process were the same for all three cultivars, 3hrs at air temperature of 70oC and 5hrs at air temperature of 50o. The amount of evaporated water is expressed in relative and absolute units of measure. The purpose of this paper is to determine which one of the three tested cultivars provides the best properties for drying, i.e. in terms of oxidation of polyphenolic compounds to find the cultivar which will provide that the final product is technologically and organoleptically the most acceptable. The results showed that the sample cv. Granny Smith expressed the least oxidation of polyphenolic compounds (browning), curved edges and shrivelled apple slices. After that the sample cv. Jonagold followed. The sample cv. Idared showed the worst results. Following the drying kinetics of all three samples, it can be concluded that the cultivars Granny Smith and Jonagold were achieving the lower maximum speed of evaporation, unlike the cultivar Idared. The cultivars Granny Smith and Jonagold have attained consistent drying and in this way the technological process was finished with a smaller temperature stress for plant tissue, resulting in a much better quality of the final product

Research on the Process of Convective Drying of Apples and Apricots Using an Original Drying Installation

“…The water activity values for dried apples range from 0.320 to 0.410, with apples dried at 80 • C yielding the highest value. The results are quite similar to those published by Paunovic et al (aw = 0.442) [36] and Polat et al (aw = 0.386) [49].…”

“…The moisture ratio (MR) and drying rate (DR) were computed using the following formulas to demonstrate the kinetics of hot air drying. Equation (1) [36,37]:…”

Experimental Study and Mathematical Modeling of Convective Thin-Layer Drying of Apple Slices

“…Apples (Malus domestica) are a widely cultivated fruit consumed either fresh or as juices, jam or dried products. They are a good source of dietary fibers, pectin, potassium, vitamin C and vitamin A and phenolic compounds [9]. Dried apples can be used in snack food, as a weak seasoning and as a complimentary ingredient of special diets [10].…”

Buffalo cheese whey hydrolyzed with Alcalase as an antibrowning agent in minimally processed apple

“…Although the 4-h hydrolysate was less efficient to control browning than metabisulfite, it is important to note that it resulted lower BI values than non-hydrolyzed whey. Considering this specific case, this hydrolysate could be used as a color stabilizer for minimally processed apples stored for up to 24 h. It could also be useful as a substitute for metabisulfites in the production of dehydrated apples, in which the interval between peeling and drying, generally less than 24 h, is determinant for PPO activity and product browning (Paunović et al 2010;Velickova et al 2014). Samples of bovine skim milk hydrolyzed by lactic acid bacteria were able to reduce BI (calculated by A 420nm ) in both potato and Chinese pear slices (Abubakr 2016).…”