Use of plant extracts in summer and winter season butter oxidative stability improvement.

Edible fats and fat containing products undergo oxidation, both during production and storage, causing a sequence of unfavorable changes. Enrichment of lipids with plant polyphenols can profitably influence their oxidative stability, additional introduction to human body can also decrease the degenerative diseases morbidity. Two seasons butter quality were analysed: winter and summer season. Oxidative stability of butter was conducted on Rancimat and Oxidograph test conditions (110oC). To evaluate antioxidant activity of different plant extracts lipid samples were enriched with green tea and rosemary extracts, alpha-tocopherol and BHT at concentration of 0.02%, counted over lipid content. It was found that pure winter butter was more stable than pure butter from summer season in Rancimat test conditions (p<0.05). No statistical differences between samples in Oxidograph test were found. Summer season butter oxidative stability was highest in sample with addition of green tea extract: 71.22h for Rancimat and 81.23h for Oxidograph test. Best antioxidative activity in winter butter showed green tea extract, where induction period was 66.5 h for Rancimat and 64.0 h for Oxidograph test. Also rosemary extract and tocopherol showed strong antioxidative activity, weaker however than green tea extract. BHT, strong synthetic antioxidant showed much lower activity. Study indicated strong antioxidant activity of examined plant extracts in lipid systems.