[4-1015-D] Food Quality (1)

[4-1015-D-03] Thermal oxidation stability assessment of extra virgin olive oil using fluorescence and transmittance imaging system

*Vincent Rotich¹, Dimas Firmanda Al Riza¹, Ferruccio Giametta², Tetsuhito Suzuki¹, Yuichi Ogawa¹, Naoshi Kondo¹ (1. Kyoto University(Japan), 2. University of Molise(Italy))

Keywords:Thermal stability, Extra virgin olive oil, Fluorescence, Transmittance, Imaging system

Extra virgin olive oil is a high-quality product with profound health benefits but is susceptible to degradation due to oxidation. Environmental conditions such as temperature, oxygen, and light promote the oxidation process. Thermal oxidation stability is of primary concern regarding food quality and safety. The ability to resist oxidation guarantees both nutritional and economic value. In this study, the thermal oxidation stability of four mono-cultivars of extra virgin olive oil from different regions of Italy was studied. The samples were placed under thermal treatment at 120°C and measurements done at equal time intervals for 180 minutes. To develop a simplified imaging system, the fluorescence characteristics of samples at the different duration of thermal exposure was measured using front-face fluorescence spectroscopy. An imaging system based on fluorescence and transmittance was developed to assess the changes that occur due to thermal exposure. The quality indices including; Peroxide value, acidity, K232, and K270 were measured following IOC (International Olive Council) standard procedures. Image processing of both colour and fluorescence images was done to ascertain the cultivar response to the thermal treatment. The fluorescence peak regions for polyphenols, oxidation products, and chlorophyll were monitored, and a comparison made between the different cultivars. New fluorescence peaks were formed at emission wavelengths 435nm and 465nm, and 570nm, suspected to be products of oxidation and hydrolysis respectively. The cultivars with a high concentration of polyphenols showed greater resistance to the formation of oxidation products. The b* component of CIE L*a*b* colour space was identified to monitor the colour changes due to thermal exposure and to ascertain the thermal stability of different cultivars of extra virgin olive oil.