Biochemical and Morphological Characterization of Heterotrophic Crypthecodinium cohnii and Chlorella vulgaris Cell Walls.

Microalgae are attractive for the food and cosmetic industries because of their nutrient composition. However, the bioaccessibility and extractability of nutrients in microalgae are limited by the rigid and indigestible cell wall. The goal of this study is to explore the cell wall polysaccharides (CWPSs) composition and morphology in heterotrophic Crypthecodinium cohnii and Chlorella vulgaris biomasses during growth. Our results showed that glucose was the major component of CWPSs and exopolysaccharides in C. cohnii. C. vulgaris CWPSs have a similar sugar profile in exponential and stationary phases, essentially composed of rhamnose and galactose. C. vulgaris cell wall thickness increased from 82 nm in the exponential phase to 114 nm in the stationary phase and consisted of two main layers. C. cohnii's cell wall was 133 nm thick and composed of several membranes surrounding thecal plates. Understanding of the microalgae cell wall helps developing a more efficient and targeted biorefinery approach.

Detection and characterization of small-sized microplastics (≥ 5 µm) in milk products.

Microplastics (MPs) have gained a high degree of public interest since they are associated with the global release of plastics into the environment. Various studies have confirmed the presence of MPs throughout the food chain. However, information on the ingestion of MPs via the consumption of many commonly consumed foods like dairy products are scarce due to the lack of studies investigating the "contamination" of this food group by MPs. This lack of occurrence data is mainly due to the absence of robust analytical methods capable of reliably quantifying MPs with size < 20 µm in foods. In this work, a new methodology was developed to accurately determine and characterize MPs in milk-based products using micro-Raman (µRaman) technology, entailing combined enzymatic and chemical digestion steps. This is the first time that the presence of relatively low amounts of small-sized MP (≥ 5 µm) have been reported in raw milk collected at farm just after the milking machine and in some processed commercial liquid and powdered cow's milk products.