Translated with DeepL
Every year, around 1 million tonnes of whey are produced in Switzerland as a by-product of the cheese industry. Around 70% of this is currently used as animal feed or disposed of directly. Whey is extremely healthy. In addition to whey proteins and lactose, it also contains B vitamins (B1, B2, B3, B6) and minerals (Na, P, Ca, Mg, Cu, Zn). Whey proteins are valuable ingredients for sports nutrition (whey protein) and are now mostly isolated from the whey, leaving behind the lactose-rich whey permeate.
The overall aim of the project is to upgrade these two by-products of the food industry, whey and whey permeate, and to return them to human nutrition. The specific idea here is to valorise them by means of fermentation using harmless lactic acid bacteria, such as those used to make yoghurt. These bacteria are able to utilise the abundant lactose in the whey/whey permeate and, through their metabolism, additionally produce folic acid (folate; vitamin B9), a B-complex vitamin with which the Swiss population is undersupplied (source: BAG). Vitamin B9 is essential for the formation of red blood cells, healthy cell growth and normal foetal development in the womb. Microbially produced vitamin B9 has health advantages over artificially produced folate, for example, it is absorbed differently by the human body. This enhances the quality, organoleptic properties and functionality of both whey substrates, enabling them to be used in other industrial products such as whey drinks or milk-based drinks.
On a trial basis, culture media with different dry matter and buffering for lactic acid bacteria were produced from whey/whey permeate. Whey/whey permeate was either added separately or in combination in different partial quantities. More than 20 strains of lactic acid bacteria with the ability to produce increased amounts of folic acid were then screened. All bacterial strains could be cultivated in these culture media, but proliferated significantly better when the culture medium contained whey. The amount of vitamin B9 produced proved to be highly dependent on the strain and medium, and the concentration after 24 hours of incubation varied greatly. All vitamin B9 assays were performed with a vitamin B9-deficient Enterococcus hirae strain and quantified using a reference standard curve. In particular, lactic acid bacteria of the genus Lactococcus (4 strains in total) were able to produce the vitamin in relevant quantities.
Vitamin B9 is unstable and is destroyed by exposure to light, oxygen or heat. In the food industry, therefore, harsh conditions prevail and this is one of the reasons why vitamin B9 is lost during food processing. To test whether the bacterial vitamin B9 survives the whey drying process in nutritionally relevant quantities, the samples were scaled up and then freeze-dried under vacuum, resuspended and concentrated. Vitamin B production was also successful in larger volumes, freeze drying worked for all samples (sufficient degree of pulverisation, little loss in terms of quantity), and the powders were easily soluble in water. In these trials, too, the strains of the genus Lactococcus proved to be particularly good. Very little to no loss of vitamin B9 was recorded during drying and the samples showed excellent concentration potential with vitamin B9 concentrations up to 6 times the original concentration. This is remarkable in view of the usual loss of vitamin B9 during food processing.
Thanks to this feasibility study, it has been shown that vitamin B9 can be produced naturally using lactic acid bacteria in whey/whey permeate and, in particular, in whey in nutritionally relevant quantities. Even under conditions closer to those in the food industry, vitamin B9 was produced efficiently and with little loss. The microbially produced vitamin B9 proved to be sufficiently stable to survive the technological processes in relevant quantities. In all experiments, strains of the genus Lactococcus showed considerable potential for large-scale production.
