1. Acidity Regulator / Buffering Agent – Changes or maintains the acidity or basicity of food/cosmetics
2. Antioxidant – Reduces oxidation to prevent the formation of free radicals which may be harmful to health
Food Additive : ANTIOXIDANT; SYNERGIST
Potassium lactate is the potassium salt of lactic acid. It is produced by neutralizing lactic acid which is fermented from a sugar source. It has E number 326. It is commonly used in meat and poultry products to extend shelf life and increase food safety as it has a broad antimicrobial action and is effective at inhibiting most spoilage and pathogenic bacteria. It is also found in sponge cakes and Swiss rolls, ice cream, jams, jellies, marmalades and sweets.
It is approved to use as food additive in EU and generally recognized as safe food substance in US.
Scientific References :
1. PubChem: https://pubchem.ncbi.nlm.nih.gov/compound/23671663
Regulatory References :
1. EU Approved Food Additive 
2. US FDA Food Additives Status List 
3. US FDA Generally Recognized As Safe (GRAS) Food Substances