From the culture broth to the erythritol crystals: an opportunity for circular economy

Abstract

The reduction of sugar intake by adults has been stated by the World Health Organization as an important strategy to reduce the risk of non-communicable diseases. Erythritol is a four-carbon sugar alcohol that is considered as a highly suitable substitution for sucrose. This review article covers approaches for the separate stages of the biotechnological production of erythritol from cultivation to the downstream section. The first part focuses on the cultivation stage and compares the yields of erythritol and arising by-products achieved with different types of substrates (commercial versus alternative ones). The reported numbers obtained with the most prominently used microorganisms in different cultivation methods (batch, fed-batch or continuous) are presented. The second part focuses on the downstream section and covers the applied technologies for cell removal, recovery, purification and concentration of erythritol crystals, namely centrifugation, membrane separation, ion and preparative chromatography, crystallization and drying. The final composition of the culture broth and the preparative chromatography separation performance were identified as critical points in the production of a high-purity erythritol fraction with a minimum amount of losses. During the review, the challenges for a biotechnological production of erythritol in a circular economy context are discussed, in particular regarding the usage of sustainable resources and minimizing waste streams. Key points • Substitution of sucrose by erythritol can be a step towards a healthier society • Biotechnological production of erythritol should follow a circular economy concept • Culture broth composition and preparative chromatography are keys for downstreaming • Substrate, mother liquor and nutrients are challenges for circular economy

Recovery of Salts from Synthetic Erythritol Culture Broth via Electrodialysis: An Alternative Strategy from the Bin to the Loop

“…The remaining salts from the culture media have to be separated from the culture broth to obtain pure erythritol, and therefore the non-used salts in the culture broth leave the process as a residual stream that has to be removed in the downstream section [34]. In the last decades, the recovery of nutrients has gained interest, becoming a multidisciplinary challenge for industry, water resources management, soil conservation, among other fields [34][35][36][37]. The transition from conventional processes to industrial circular processes represents an opportunity to tackle resource management and climate change concerns.…”

“…The removal of salts from erythritol culture broth is used as an example of a more general approach for recycling residuals from biotechnological culture and so far has been addressed by adsorption on ion exchange resins in the downstream section [34,[39][40][41]. The principle behind this separation is the removal of salts by exchanging their position with other exchangeable ions (Na + , H + , among others) within cationic and anionic exchange resins.…”

Erythritol: An In-Depth Discussion of Its Potential to Be a Beneficial Dietary Component

“…Obviously, dietary erythritol intake does not explain the associations between circulating erythritol and cardiometabolic disease that were observed in these two studies. However, even for studies in which samples were collected after erythritol introduction into the food supply, it needs to be considered whether the global per capita production of erythritol, estimated at 0.023 g/day in 2019 [ 12 , 13 ], supports consumption levels high enough to obtain discernable associations with cardiometabolic disease. It seems unlikely.…”

“…Furthermore, the 2019 global production would suggest most consumers have negligible exposure to erythritol. The 2019 global per capita production of the predominant caloric sweeteners, sucrose and HFCS, exceeds the erythritol production by over 3000-fold (67 gm/day for sucrose and HFCS; 0.023 gm/day for erythritol) [ 12 , 13 ]. However, erythritol’s production and consumer use are expected to increase [ 14 ].…”

Polyols - What do we know about their impact on the gut microbiome?

“…Erythritol (E-968) is a natural sweetener as a four-carbon alcohol with no optical activity [1]. Mass production of erythritol is demanding and differs from production of other polyols [34]. On the industrial scale it is obtained through fermentation of yeasts, where the main primary carbon source that is formed is glucose.…”