Watermelon juice: a promising feedstock supplement, diluent, and nitrogen supplement for ethanol biofuel production

Table 2 Fermentation of processed sugar supplemented and diluted with watermelon juice^a

Beginning (Fermentable sugars) (%, w/v)	pH	24 h (Yeast) (cells/ml)	24 h Respiration rate (CO₂, L/h)	Final (Unfermented sugar) (%, w/v)	Final (Ethanol) (%, w/v)	Time to completion (h)
18.3	3.1	6.8 × 10⁷	4.6	0	8.32	36
25.4	2.7	7.8 × 10⁷	3.8	0.4	11.6	86
29.3	2.8	5.1 × 10⁷	4.4	5.6	12.1	92
40.3	2.8	3.7 × 10⁷	2.8	18.2	10.2	93
40.3^b	2.8			17.6^b	10.5^b	160^b
26.9	5.0	11.0 × 10⁷	4.6	0.21	10.33	52
30.5	5.0	9.0 × 10⁷	4.4	0.18	11.53	68
40.95	5.0	7.9 × 10⁷	4.0	5.4	14.0	160

^aWatermelon juices from the 2008 Louisiana crop and the 2007 and 2008 Oklahoma crops were employed. Chromoplasts were removed from the respective juices before their use in fermentation.
^bThis is the continuation of the fermentation presented immediately above; it demonstrates that little or no further ethanol production occurred.

ISSN: 2731-3654