## 3 Greek Dried Grapes: Source of Bioactive Compounds  
### Nutritional Profile and Bioactive Compounds  
For the production of Greek dried grapes, the dominant applied method is traditional open sun drying, where grapes are layered on trays on the ground and left to dry until the required moisture content (less than 16%). As an exception, Sultanina from Crete might be produced via conventional air drying on some occasions, whereas sulfite pre-treatment might also be applied [24]. However, Corinthian currants are obtained via sun drying, although shade drying is also emerging as an alternative drying method abandoned from producers for many years [23]. A preceding study, evaluated sun (open and under shade) and industrial drying operation on Sultana seedless and black currants, indicating that forced air drying enhanced drying rates in both types of grapes [48]. Equally, it was stressed that industrial drying improved the final product quality in comparison with solar dehydration. Recent studies, focusing to undertake the effect of drying on currant composition and nutritional value will be listed below. Grapes, raisins, and currants constitute a significant source of micro- and macronutrients, including sugars, vitamins, minerals, and fiber but they also deliver a diversified range of bioactive compounds (e.g., polyphenols and carotenoids). The latter compounds are non-nutritional, but contribute in health wellness and longevity through the prevention and control of non-communicable diseases, particularly in genetically predisposed populations [11]. Raisins content includes more than 62% of sugars, with the monosaccharides glucose and fructose being in almost equal proportions, and lower amount of sucrose [24]. Therefore, raisins constitute an easily absorbed form of energy, providing moderate Glycemic Index (GI). It is worth noting that a health claim concerning \"Cornithian raisins\" and the ability to lower blood glucose rise after their consumption, has been already submitted for EFSA's approval [49]. Currants have received significant attention, as they are nutrient dense fruit with a high concentration in bioactive compounds, along with the absence of total fat and cholesterol. An indicative composition of selected nutrients in indigenous Greek currants (Cornithian and Zante currants) is presented in Table 1. Similar to raisins, currants provide a good source of dietary fibers, minerals like calcium, iron, magnesium, phosphorus, and potassium along with vitamin B complex, whereas demonstrating low amount of sodium [22; 24]. For instance, [PERSON] et al. [31] evaluated the micronutrient and folate (vitamin B9) content of several Australian and imported dried fruit. Zante currants were also included, exhibiting higher calcium concentration when compared to other varieties, iron levels deemed also significant, although folate quantity was lower compared to Australian currants. The final composition of currants comprises a dynamic modification deriving from multiple variables, including cultivation and weather conditions (e.g., irrigation, sun exposure) among others. Likewise, [PERSON] et al. [50] studied the simple sugar profile of Corinthian currants, over three consecutive crop years. Fructose, glucose, sucrose, maltose, and total sugar content along with moisture, ash, fat, and protein content were evaluated and related to cultivation conditions (altitude). The authors noted that differences in the composition were indeed observed, however, they were not significantly related to the final product quality. Average values obtained for moisture, fat and protein were found 13.8 \(\pm\) 0.5%, 0.43 \(\pm\) 0.06% and 2.2 \(\pm\) 0.4%, respectively. Equal amounts of fructose and glucose were measured, whereas sucrose and maltose were in low levels. On top of that, as previously noted, dehydration method of currants could potentially affect composition. [PERSON] et al. [23] studied sun and shade drying and further analysed the phytochemical and sugar composition over three consecutive crops.