This article reviews various aspects of foam-mat drying such as foam-mat drying processing technique, main additives used for foam-mat drying, foam-mat drying of liquid and solid foods, quality characteristics of foam-mat dried foods, and economic and technical benefits for employing foam-mat drying. Foam-mat drying process is an alternative method that allows the removal of water from liquid materials and pureed materials. In this drying process, a liquid material is converted into foam that is stable by being whipped after adding an edible foaming agent. The stable foam is then spread out in sheet or mat and dried by using hot air (40-90°C) at atmospheric pressure. Methyl cellulose (0.25-2%), egg white (3-20%), maltodextrin (0.5-05%), and gum Arabic (2-9%) are the commonly utilized additives for the foam-mat drying process at the given range, either combined together for their effectiveness or individual effect. The foam-mat drying process is suitable for heat sensitive, viscous, and sticky products that cannot be dried using other forms of drying methods such as spray drying because of the state of product. More interest has developed for foam-mat drying because of the simplicity, cost effectiveness, high speed drying, and improved product quality it provides.

The study examined the effect of drying compartment and maltodextrin concentration on the functional properties of Bambara groundnut milk powder (BGNMP). Bambara groundnut milk (BGNM) was prepared from Bambara groundnut (BGN) flour and water, further processed into BGNM and dried using the spray drying process. Total solids of BGNM were increased with 5, 10, and 15% of maltodextrin. Functional properties of BGNMP were analyzed. Water absorption indices (WAI), wettability, and water solubility indices (WSI) ranged from 0.19 to 0.45 g/g, 136.8 to 292.4 s, and 85.18 to 90.25%, respectively. BGNMP (10%) was significantly (p < .05) higher in WSI (88.80%) compared to BGNMP with 5% maltodextrin. BGNMP (10%) was significantly higher (p < .05) in WAI (0.40 g/g) compared to BGNMP with 15% maltodextrin. BGNMP samples color characteristics were significantly (p < .05) different with an acceptable color difference (ΔE). BGNMP (10%) had acceptable hydration properties over BGNMP (5%, 15%). Practical applications Bambara groundnut (BGN) is underutilized, stated to have little economic importance. However, recent studies have proven BGN to be promising in improving food security through research, resulting in food product (milk, yoghurt, fiber) development. Milk from BGN has been reported with acceptable physical attributes and comparable to existing plant milk. However, nothing has been reported on BGN milk powder (BGNMP). The development of BGNMP will promote the use of BGN. This will result in the social development of the country, by creating job opportunities for woman farmers and improve lives of individuals and providing gender empowerment. The success of this study will also provide food nutrition, security, and sustainability, as BGN is nutritious, widely, and readily available throughout Africa regions. Expanded utilization of BGN will encourage its production (harvesting) resulting in exporting of the material, improving the country's economy by opening up new and improved investment opportunities and new markets.

Yogurt is a milk product produced from fermentation of milk sugars into lactic acid by the addition of yogurt starter culture containing Streptococcus thermophilus and Lactobacillus delbrueckii ssp.