*3.1. Chemical Analysis*

Table 1 displays the macronutrient composition of both whole and defatted *Aurantiochytrium* sp. used in this study. A total lipid content of approximately 43% positions the samples used among the higher range of this parameter among other published results. Trovão et al. (2020) situated their set of *Aurantiochytrium* sp. within the 14 and 24% fat content range in their studies, while Ryu et al. (2013) achieved approximately 38.1% of lipidic weight growing *Aurantiochytrium* sp. in spent brewer's yeas<sup>t</sup> [35,36]. Regardless, percentages as high as the ones presented here were previously achieved [37]. The protein content is within the expected values for cultured *Aurantiochytrium* sp., with authors such as Sami et al. (2013) and Moran et al. (2019) reporting this parameter at around 15% [38,39]. Fibre content was found to be about 31% of its dry weight, which is a percentage that stands far higher than most published results for *Aurantiochytrium* sp. Moran et al., 2019 found a maximum fibre content of around 3.4% in *Aurantiochytrium limacinum*. Such high values are not common even in other thraustochytrids [22].


**Table 1.** Macronutrient analysis performed on the whole *Aurantiochytrium* sp. (WA) and on its defatted counterpart (DA), shown as a percentage of dry weight. Each result is the average of at three measures ± standard error.

Looking at the macronutrient profile in isolation, *Aurantiochytrium* sp. in its defatted form already presents itself as a highly promising food product, with unusually high protein and dietary fibre contents. Similar profiles are found in marine organisms used as supplements, such as Spirulina and Chlorella [6]. With the loss of its lipid fraction, valued for its high PUFA content, the spent *Aurantiochytrium* sp. biomass may lose some of its nutritional richness. In turn, this depleted biomass is now much lighter in caloric content and thus much more compatible as a protein and dietary fibre supplement that is easily incorporated in a variety of diets.
