Table 1.

Different sugar crops investigated for ethanol production using sugar juices as feedstocks.

Name of the crops	Major investigation	Major achievements	Reference
Sugarcane (Saccharum officinarum)	Juices were studied (i) without adding supplement, (ii) with addition of 0.5% yeast extract, and (iii) with addition of yeast extract, thiamine, and micronutrients	The highest ethanol concentration (39.4–42.1 g/L) was found in (iii), while the lowest was 11.0 g/L and found in (i)	[61]
	Enrichment technique was applied to isolate a thermotolerant yeast from cane juice for ethanol production at elevated temperature	Isolation and selection of thermotolerant yeast strain that produced high concentrations of ethanol at both 40 and 45°C from the juice	[59]
	Juices were supplemented and cells were adapted to galactose medium	Higher (30.0%) ethanol was found with adapted cells than nonadapted cells	[26]
Sugar beet (Beta vulgaris)	Juices were ultrafiltered and were supplemented with mineral salt	Ethanol concentration was found to be 85.0–87.0 g/L	[30]
	Flocculating and nonflocculating yeasts along with Z. mobilis were used through immobilization on loofa sponge	The highest ethanol yield (0.44 g/g) with the lowest productivity (0.08 g/h/L) was found by Z. mobilis	[3]
Sweet sorghum (Sorghum bicolor)	Five different genetic varieties (Keller, BJ 248, SSV84, Wray, and NSSH 104) were investigated for ethanol production	Keller variety produced the highest ethanol (9.0%, w/v)	[118]
	Impact of storage on sugar content loss of juice was studied	Up to 20.0% free sugars lost in 3 days at ambient temperature	[119]
Watermelon (Citrullus lanatus)	Juice was used as diluent, additive, and nitrogen source for processed sugar or molasses fermentation	As much as 25.0% w/v sugar was fermented at pH 3.0 (ethanol yield was 0.41–0.46 g/g) or up to 35.0% w/v sugar at pH 5.0 with an ethanol yield of 0.36–0.41 g/g	[120]
Dates (Phoenix dactylifera)	Juices were extracted from 3 genetic varieties of dates (Kunta, Bouhatem, and Eguoua) and fermentation was studied at 30°C and natural pH	All varieties produced ethanol with a maximum concentration of 25.0%, v/v	[111]