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In this paper, two Natural Deep Eutectic Solvents, glyceline (Gly) and glyceline-water (GlyW), containing choline chloride as acceptor H-bond compound and glycerol as donor H-bond group are studied. For glyceline the mole relation is 1 (choline chloride): 2 (glycerol) and for glyceline-water the mole relation is 1 (choline chloride) : 1.99 (glycerol) : 1.02 water. The ternary NADES has been synthetized and characterized chemically by NMR techniques for this work. Several thermophysical properties in a wide range of temperature (278.15-338.15) K and at atmospheric pressure (0.1 MPa) have been measured for both compounds: density, , speed of sound, , refractive index, , surface tension, , isobaric molar heat capacity, , , kinematic viscosity, , and electric conductivity,. Furthermore, some related properties have been also calculated: isobaric expansibility, , isentropic compressibility, , molar refraction, , entropy and enthalpy of surface formationper unit surface area (Δ and Δ), and dynamic viscosity, , and viscous flow and electrical conductivity activation energies. The results have been discussed in terms of the effect of temperature and the inclusion of water. We conclude that the compound containing water into the structurehas a higher molar volume and a higher fluidity. The binary NADES (Gly) is a more structured liquid than ternary one (GlyW).

Background: A possible future shortage of feed protein will force mankind to explore alternative protein sources that can replace conventional soymeal or fishmeal. Several large industrial organic side-streams could potentially be upgraded to feed protein using a fermentation process to generate single cell protein. Yeast is the most widely accepted microorganism for production of single cell protein, because of its superior nutritional quality and acceptability among consumers. Here, we have assessed the growth of four different yeasts, Cyberlindnera jadinii, Wickerhamomyces anomalus, Blastobotrys adeninivorans and Thermosacc ® Dry (Saccharomyces cerevisiae), on media composed of enzymatically saccharified sulfite-pulped spruce wood and hydrolysates of by-products from chicken, and we have characterized the resulting yeast biomass. Results: Generally, the yeast grew very well on the spruce-and chicken-based medium, with typical yields amounting to 0.4-0.5 g of cell dry weight and 0.2-0.3 g of protein per g of sugar. B. adeninivorans stood out as the most versatile yeast in terms of nutrient consumption and in this case yields were as high as 0.9 g cells and 0.5 g protein per g of sugar. The next best performing yeast in terms of yield was W. anomalus with up to 0.6 g cells and 0.3 g protein per g sugar. Comparative compositional analyses of the yeasts revealed favorable amino acid profiles that were similar to the profiles of soymeal, and even more so, fish meal, especially for essential amino acids. Conclusions: The efficient conversion of industrial biomass streams to yeast biomass demonstrated in this study opens new avenues towards better valorization of these streams and development of sustainable feed ingredients. Furthermore, we conclude that production of W. anomalus or B. adeninivorans on this promising renewable medium may be potentially more efficient than production of the well-known feed ingredient C. jadinii. Further research should focus on medium optimization, development of semi-continuous and continues fermentation protocols and exploration of downstream processing methods that are beneficial for the nutritional values of the yeast for animal feed.

Hydrolyzed protein-rich byproducts from food production may find a variety of applications, for example, as rich ingredients of fermentation media. We have conducted a study of the enzymatic hydrolysis of three byproducts from Norwegian food industries: chicken byproducts, mixed pork and beef byproducts, and salmon viscera. The efficiency and optimization of the enzymatic hydrolysis were evaluated using endogenous enzymes alone and in combination with commercial proteases. Hydrolysis reactions were conducted with freshly thawed raw materials using short incubation times and including an initial temperature gradient from 4 to 60 °C to both harness the power of endogenous enzymes and minimize microbial contamination. Subsequently, hydrolysates were characterized by analyzing the total recovery of protein, the peptide molecular-weight distribution, and the composition of total and free amino acids. The action of endogenous enzymes played an important role in raw-material hydrolysis, particularly when hydrolyzing salmon viscera but less so when hydrolyzing chicken byproducts. For pork-beef and chicken byproducts, the addition of Alcalase or Papain improved protein recovery, reaching levels up to 90%. Next to showing efficient hydrolysis protocols, the present data also provide a comparison of the amino acid compositions of hydrolysates derived from these three different protein-rich byproducts. Growth studies showed that the obtained protein-rich hydrolysates from meat and fish industries are a promising alternative for expensive nitrogen sources that are commonly used for fermenting yeasts.