# Powdered Foods: Structure, Processing, and Challenges: A Review
## 7 Powdered Products: Case Studies
### Non-Alcoholic Beverages  
Non-alcoholic beverages such as coffees and teas are widely consumed around the world, either for the beneficial properties of bioactive compounds or for the effects produced by caffeine (increased alertness and reduced fatigue). According to the National Center for Health Statistics (NCHS), the contribution of coffees and teas constituted more than 20% of all nonalcoholic beverages consumed by the US population between 2015 and 2018, in which coffee was the most consumed beverage (14.9%) after water, and tea the fourth most consumed beverage (8.4%) [81; 82].  
[PERSON] and [PERSON] [83] evaluated different drying methodologies, namely spray-freeze-drying (SFD), freeze-drying, and spray-drying, to produce soluble coffee. SFD showed a higher retention of volatile compounds (93%), an important characteristic to produce soluble coffee, since coffee is often appreciated for its aroma, followed by freeze-drying (77%) and spray-drying (57%). The authors also evaluated the morphology of the powders, in which the SFD and spray-drying processes resulted in spherical shapes, while the freeze-drying process yielded a flaky structure [83].  
[PERSON] and [PERSON] [84] optimized powdered green tea extracts (_Camellia sinensis_) extracts by testing different concentrations of maltodextrin and the inlet temperature in the spray-dryer, in which the authors found that with increasing inlet temperature there was a decrease in solubility and moisture content. On the other hand, the increase in maltodextrin concentration decreased the content of phenolic compounds and increased the hygroscopicity of the powder [84]. Regarding the antioxidant activity of _Vitex_ spp. leaves [85], the microwave and freeze-drying methods maintained the antioxidant properties of the leaves, while oven- and sun-drying methods resulted in deterioration of the compounds.  
The drying conditions used are essential to produce a high-quality soybean milk powder, in which the protein dispersibility index (PDI) is a factor to determine the solubility of the soybean powder in water, affected by the pH and the manufacturing process of the soybean milk product [86]. To produce soy beverages, [PERSON] et al. [87] prepared water-soluble extracts of powdered soybean, in which the beverage prepared with the extract diluted to 10% presented the best general acceptance and with a greater purchase intention among the evaluated consumers.  
The agglomeration process has already been discussed due to the benefits of agglomerated powder, such as improved rehydration properties. [PERSON] et al. [88] investigated the effect of the agglomeration process on powdered bayberry produced via spray-drying. Among the results obtained, the wettability power was the most significant, with a reduction time of 2 min to 15 s, besides decreasing bulk density and increasing the particle by more than 2 times. For powdered sugarcane juice, [PERSON] et al. [69] evaluated the physical properties obtained from the spray-drying process, obtaining spherical particles with high hygroscopicity and good rehydration properties, such as high dispersibility, wettability, and solubility. Furthermore, the authors evaluated the incorporation of citric acid into sugarcane juice before the drying process, which had a negative effect on the reconstitution properties but produced particles with a smooth surface and more agglomeration [69].  
Alternatives that help with rehydration characteristics are also investigated, helping to improve the texture or flavor of the final product. [PERSON] et al. [89] evaluated the effect of adding sugar to powdered coconut beverages, finding that the concentration of sugar affects the solubility of the drink; the larger the sugar particle size, better the rehydration process. Furthermore, the authors concluded that the mixture of two sugars (sucrose and lactose) had better rehydration results compared to the individual sugars studied [89].