Flash 2000 chns o

The freeze-dried hydrolysates were analyzed for their protein, lipid and moisture content. A Flash 2000 CHNS/O elemental analyzer (Thermo Scientific, Waltham, MA, USA) was employed to determine the protein content of meals and hydrolysates. Here, the samples are subjected to complete combustion, and a thermal conductivity detector identified the electrical signal of combustion products (CO₂, H₂O, N₂ and SO₂), which is proportional to each elemental concentration (C, H, N and S). The nitrogen-to-protein content factor was assumed to be 5.3, following the work of Rhee K [4 (link)].
The lipid content of the PPH was determined after four sequential extractions with a hexane and 2-propanol mixture (1: v/v). Briefly, a certain amount of hydrolysate (between 0.2 and 1.0 g) was mixed with 5 mL distilled water, 20 mL of solvent mixture and then vortexed for 5 min. After that, it was centrifugated at 1200× g for 5 min. The supernate phase was taken to evaporate solvent, and the oil content was quantified by dividing oil mass per hydrolysate mass used.
The moisture content of the PPH was determined by means of an infrared moisture analyzer (AD-4714A, A&D Company, Oxford, UK).

Two-phase OMW was sampled from a representative processing company in the Meknes region (Morocco). It was air-dried and ground with SM 300 knife-cutting mill (Ø_sieve 1 mm, Retsch GmbH, Germany). Compositional analysis of OMW was done according to standard laboratory protocols of the National Renewable Energy Laboratory (NREL) [[39] (link), [40] , [41] , [42] , [43] , [44] ] for total solids, ash, extractives, and lignin contents. Carbon, hydrogen, nitrogen, sulfur, and oxygen elements were determined using FLASH 2000 CHNS-O organic elemental analyzer (Thermo Scientific, France; Eager Xperience interface) following the supplier’s protocol. All carbon sources used in fermentation were dried at 40 °C for 24 h before use.