The goal of the present study is to investigate the effect of explosion puffing and convection air drying on the physical, chemical and sensory properties of dried seedless grape, and cost of operation. The obtained results showed that, the drying rate of puff drying method (PD) was faster than that of convection air drying method at the corresponding drying condition of (60°C and 1.5 m/s air velocity). The seedless grape samples dried by PD were the best for the most of physico-chemical quality properties such as color index, texture, rehydration ratio, and shrinkage rate compared to similar samples dried by AD that required a longer time. The seedless grape dried by PD method had the highest amount of total phenolic compounds (276.73 mg/100g DM) than that in convection air drying. The highest value of total carotenoids (84.44 mg/100g DM) was found in seedless grape dried by PD method. The PD drying process led to retention of total flavonoids in dried seedless grape samples at a wide rate depending on the drying time compared to the AD drying methods. The PD technique exhibited the ability to obviously quench the DPPH radical compared to the AD method. In conclusion, the seedless grape samples dried by PD exhibited good sensory properties and better acceptability. PD can meet the four major requirements in drying foods: short time of operation, energy efficiency, cost of operation, and quality of dried products which indicates that puff drying is a good choice for grape processing.

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Processing of fruits, vegetables, and oilseeds results in high amounts of by-products. The purpose of this study is to investigate the physicochemical and techno-functional properties of grape (GS) and peanut skin (PS) by-products. Moisture, protein, fat, fiber, ash and carbohydrate of GS and PS powders were (7.37 and 2.34%), (6.76 and 5.59%), (2.55 and 20.68%), (12.91 and 14.19%), (6.62 and 1.87%) and (63.79 and 55.33%), respectively. Total phenolic compounds (TPC), flavonoids and antioxidant activity (DPPH radical scavenging) of GS and PS powders were (41.60 and 212.21 mg GE/gm d.w.), (3.99 and 16.83 mg quercetin equivalent / gm d.w.) and (10.88 and 63.30%), respectively.Both GS and PS powders had remarkable color attributes with promising role as a food natural colorant. GS powder has reddish-purple color with L* (lightness) value by (46.93), a* (redness) value (7.64), and b*(yellowness) value (6.87). While PS powder color ranging from light brown to deep red, with values of L*, a* and b* were (60.83, 9.23 and 16.77), respectively. Functional properties of the GS and PS powders (mesh 60 = 0.25 mm), both powders exhibited bulk density (0.999 and 0.457 g/ml), water absorption index (2.87 and 4.02 g/g), water solubility index (0.51 and 0.08 %), oil absorption index (1.50 and 1.70 ml/g) and swelling index (1.06 and 1.20 ml/g) for GS and PS powder respectively. Considering these results, it's clear that the GS and PS powders can provide an inexpensive source of dietary fibers and polyphenols for use as functional ingredients in foods or dietary supplements. Moreover, they had distinguished techno-functional properties. Such findings could introduce/valorize the GS and PS powders to play technological and health promoting desirable roles in many food products.