Purpose: This publication provides a description of RDC Glokor’s own research into the
effectiveness of the lactic fermentation process of lactose, lactic acid concentration and
polylactide (PLA) production by ring-opening polymerization obtained from the condensation
of two molecules of lactic acid. Furthermore, this publication sets out to determine potential
applications of the PLA as a commercial material with a selection of thermal properties.
Design/methodology/approach: In the described research works, a lactic fermentation
process was used in which lactose is converted to lactic acid with the participation of Lactic
Acid Bacteria. Polylactide was obtained indirectly by Ring Opening Polymerization and by
direct polymerization, straight from lactic acid, omitting the intermediate stages. Next, the
obtained lactide and polylactide were examined by spectroscopic methods (IR, NMR) to
determine their purity. Thermal methods (TG, DSC) to determine thermoplastic properties,
i.e. softening point, decomposition temperature and glass transition temperature.
Findings: Obtained from waste whey, PLA and its copolymers are excellent biodegradable
polymers that have the potential to be used in medicine as resorbable surgical strands,
biopolymers for implant production, as well as in many industries including for the production
of biodegradable bottles and disposable packaging, 3D printer cartridges.
Research limitations/implications: The research on lactic acid and lactide polymerization
described in this article is still a new issue that requires further research to optimize PLA
processes with industry-specific thermoplastic and physicochemical properties.
Originality/value: In the basic waste processing of milk, there is a large volume of whey
sour, which is ecologically dangerous for waste treating. Due to the high content of lactose
(up to 6%) this waste can be used as a raw material in the lactic fermentation process in
which lactose is converted to lactic acid with the participation of lactic acid bacteria. Lactic
acid can be concentrated and subjected to a dehydration process to lactide, which in the
final stage is subjected to the process of ring-opening polymerization in order to produce
biodegradable polylactide. The described process of carrying out the lactose contained in
PLA whey is an innovative way to obtain a biodegradable usable polymer, which can be used
to replace plastics such as polypropylene and polyethylene.
Corrigendum to “Simultaneous synthesis of lactic acid and hydrogen from sugars via capnophilic lactic fermentation by Thermotoga neapolitana cf capnolactica” [Biomass and Bioenergy 125 (2019) 17–22]
