Osmotic Dehydration and Hot-Air Drying of Pineapple (Ananas comosus)

Diego F. Tirado*, Kevin J. González-Morelo, Mariano J. Puerta, Oscar Y. Ahumada, Diofanor Acevedo Correa * Department of Chemical Engineering, School of Chemistry, Universidad Complutense de Madrid, Av. Complutense s/n, 28020, Madrid, Spain. ResearchGroupNutrición, Salud y Calidad Alimentaria (NUSCA), Universidad de Cartagena, Av. El Consulado, St. 30 No. 48-152, 130015, Cartagena de Indias, Colombia. Corresponding author: ditirado@ucm.es.

solutions that In the same w oncentrations.
x by using sucrose 1    In add the elimi range be Barbosa the first 5 al., [12]     In dehydration and hot-air drying processes, the mass decreases as the time of the process increases, but in the case of OD, this method undergoes the first stage of osmosis as previously indicated where solutes are exchanged between the solution and the food. It is precisely there when the fruit mass begins to experience a slight increase since the velocity of the solute's entrance during the first two hours is higher than that of the water outlet until the process is stabilised and dehydration begins [1].
In the case of HFD as shown in Fig. 13 and 14, the mass always tends to decrease, experiencing most significant loss in the course of the process, so it is in this interval of time where drying has a higher incidence on the fruit, also coinciding with results obtained by Zapata and Castro [24] who argued that in this interval of time was where the most considerable loss of mass occurs in dehydrated fruit by this method. Afterwards, the fruit begins to experience a tendency to maintain its weight constant or practically unchanged.
From Fig. 13 it can be seen that all the treatments were carried out until an optimal drying (almost 100%), but it was also observed that there were differences among them, specifically regarding drying time. For example, the osmotic treatment that reduced water loss in greater proportion was fructose at 40 °Brix, since it was the treatment that reached a maximum drying time after 2 h. This was mainly because fructose has a high osmosity index in relation to other compounds. This osmosity is greater for fructose since its molecular weight is lower and its ionising capacity is higher. Fig. 14 showed better results with the mixture glucose-fructose with a concentration reaching a constant massat 2.5 h.

E. Statistical analysis of osmotic solutions
The ANOVA results showed that the type of osmotic solution, concentration and time, all with a p-value lower than 0.01 were highly significant for WR, WL and SGduring osmodehydration of pineapple (Table 1).For a better analysis of the process and experimental design, interactions were made between the factorstype of osmotic solution (A), concentration (B) and time (C), and it was observed that the AB, AC and BC interactions had a highly significant difference with p-values. This meant that WR, WL and SG during the process were influenced by the type of osmotic solution, concentration, time and its interactions. That is, the process wascontrolled by the kind of osmotic solution, concentration, time and its interactions.

IV. CONCLUSIONS
It could be concluded that the product obtained good results in the preservation through osmotic dehydration highlighting the solutions with glucose and honey and mixtures of glucose-fructose that caused more dehydration in the concentrations established. On the other hand, hot-air drying provided complete dehydration of the product, possibly allowing for a prolonged shelf life. Static analyses confirmed that there was a strong influence of the type of osmotic solution, operating time and concentration on weight loss, water loss, and solids gain. It is expected through this research to support the industrial sector, which embraces this technology as a means of production.