No abstract

Date palm fruits have special considerations in people's social life in North Africa and the Middle East regions (Zaitoon et al., 2016). Date palm fruits have high nutritional values: they are considered to be a rich source of sugar, fiber, minerals, and considerable amounts of vitamin A, B-complex, and C (Al-Farsi & Lee, 2008; Al-Khayri et al., 2015). They also have remedial effects, due to their phytochemical contents; involving carotenoids, polyphenols, tannins, and sterols, which are known for their antioxidant activity, cholesterol-lowering properties, and chemoprevention of cancer, diabetes, and cardiovascular diseases (Barnett et al., 2000; Johnson et al., 2015). Egypt is the first in the production of date fruit with 1,562,171 metric tons in 2018, accounting for 18.3% of the global production (FAOSTAT, 2020). Medjool dates are obtained at the tamr stage (the third stage of date fruits ripening, where the fruits are hard or semi-hard with dark colors (Johnson, 2011)). Medjool date is becoming an interesting variety to the Egyptians. It is grown in southwest Egypt. It is economically promising.

Cistanche deserticola is one of the most precious herbal medicines and is widely used in the pharmaceutical and healthy food industries. Steaming is an important step prior to drying in the processing of C. deserticola. This research investigated the effects of high-humidity hot air impingement steaming (HHAIS) parameters such as temperature, time, and relative humidity (RH) on drying characteristics, weight loss, color, microstructure, and active components of C. deserticola slices. The results showed that the steaming process caused a weight loss in C. deserticola; however, increasing the RH reduced the weight loss. Starch gelatinization observed from the microstructure of the steamed samples explained their long drying time. The Page model can well fit the drying process with a high R2 (>0.956) under the drying conditions of 60°C and 6 m/s. Steaming increased the content of phenylethanoid glycosides, and the highest content was obtained at 95°C and 60% RH for 20 min, 75°C and 70% RH for 20 min, and 75°C and 60% RH for 30 min. The steamed samples appeared in an oil black color. When the color difference (ΔE) values were in the range of 16.79–20.12, the contents of echinacoside and acteoside reached the maximum. Steaming at 95°C and 60% RH for 20 min, 75°C and 70% RH for 20 min, and 75°C and 60% RH for 30 min are the optimum process conditions. The results from this work provide innovative steaming technology and suitable processing parameters for producing C. deserticola decoction pieces with a high quality, which will broaden its potential application in the functional health food industry.