Evaluation of different drying systems as an alternative to sun drying for figs (Ficus carica L)

The aim of this work was to study the effect of different drying systems on the quality characteristics of dried figs as an alternative to sun drying. Fresh figs were dried as follows: drying in a convection oven at different temperatures; pre-treatment by soaking in osmotic solutions at different concentrations; pre-treatment with K2CO3 + olive oil, combined or not with osmotic solutions; pre-treatments with ultrasound combined or not with osmotic solutions; sun drying (control). Moisture, water activity, microbial counts, firmness and sensory quality were measured at the beginning, at the mid-way and at the end points of the drying process. The figs dried with all the artificial drying systems tested needed between 1 and 3 days to reach the required moisture content of 24% wet basis (w.b.), while the sun dried figs needed 15 days to reach the optimal moisture. Regarding mold counts, firmness and sensory quality, the best results were observed for the treatments with ultrasound combined with osmotic solutions. Thus, this treatment could be a good alternative to the sun drying process. Industrial relevance: Sun drying of figs is a widely-spread practice in tropical and subtropical countries. Nevertheless, the slowness of the process, depending on the climatic conditions, can result in diverse problems such as the loss of quality and dramatically increases the rapid growth and proliferation of microorganisms such as molds which can produce mycotoxins, resulting in high losses of the product and consequently, economic losses. Therefore, the major problem of these fruits is fungal growth and subsequent mycotoxin production, which are considered an important problem throughout the world in terms of public health, agriculture and economics. For this reason, there is an increasing demand by the productive sector for the development of new drying technologies to shorten the drying time and to enhance the safety of these products by reducing or even inhibiting fungal proliferation due to the optimal and controlled drying conditions of these proposed technologies. This study represents a great opportunity to apply new techniques in order to reduce the drying period and to obtain a product with suitable sensory, safety and quality characteristics. Therefore, this study is a useful tool which will help the productive sector, which is in a critical situation, to avoid all problems mentioned above. (C) 2016 Elsevier Ltd. All rights reserved.