Microbial protein production from lactose-rich effluents through food-grade mixed cultures: Effect of carbon to nitrogen ratio and dilution rate

Valorisation of industrial hemp (Cannabis sativa L.) residues and cheese whey into volatile fatty acids for single cell protein production

“…Based on these results, it was decided to increase the C/N ratio (i.e., 5.0) ( Table 3 ) in B 4 and decrease the duration of the experiment to avoid an excessive stripping of the nitrogen fed. In fact, a typical aerobic fermentation process has a short operating period (e.g., 2–48 h) [ 5 , 33 ]. The test lasted two days, during which the VFAs were almost completely consumed (i.e., 92%) ( Fig.…”

“…The protein content of the produced SCP was measured on the biomass harvested through centrifugation at 6000 rpm for 10 min and washed in a 0.9% NaCl saline solution. The organic nitrogen content of the biomass was measured as TKN [ 43 ], and a conversion factor of 6.25 was applied to calculate the final protein concentration [ 33 , 45 ].…”

“…Finally, for the batch aerobic tests, the biomass yield coefficient (Y), i.e., the amount of biomass produced per unit of substrate consumed (i.e., sCOD) [ 33 ], was calculated according to equation (5) : where refers to the sCOD value at the beginning of each test (i.e., day 0), and refers to the value of the sCOD at the chosen sampling time i .…”

“…Concerning CW, this substrate represents the main waste of the dairy industry and is made of different dilutions of milk and washing water, resulting in an important organic load, i.e., up to 100 g L −1 of chemical oxygen demand (COD) [ 19 , 31 ]. Moreover, due to its high organic nitrogen (i.e., 0.2–5.4 g L −1 ), fats (i.e., 0.08–10.58 g L −1 ) and lactose (i.e., 0.18–60.00 g L −1 ) content [ 32 , 33 ], CW is considered a nutritional supplement and an optimal co-substrate to enhance the organic acids production from the fermentation of lactose [ 31 ] through its microorganisms, constituted mainly by lactic acid bacteria (LAB), and to further support the production process [ 19 ]. According to Condon [ 34 ] and Zotta et al.…”