Investigation on effects of electroplasmolysis treatment on extraction yield of natural colorants from tomato and spinach

In the food industry, various natural and synthetic colorants are used. Although natural pigments are generally less stable and have higher cost than synthetic colorants, there has been an increasing trend towards replacement of synthetic colorants by natural pigments in recent years. Because natural pigments have safety and health benefits, and there is a strong consumer demand for more natural products. Tomato and spinach are rich in natural colorants such as carotenoids, chlorophylls and have high production potential in Turkey.Solvent extraction is generally used in extraction of natural colorants from natural sources. However, it is necessary to perform extraction more efficiently. To achieve this, various pretreatments can be used. One of these pretreatments is electroplasmolysis. Electroplasmolysis is a plasmolysis event that occurs in cells due to electric current.In this study, the effects of electroplasmolysis and heating in water bath process on extraction yield of natural colorant extraction from tomatoes and spinach were investigated. In electroplasmolysis treatment, three different voltage gradients (40, 60, 80 V/cm) and three different application periods (4, 8 or 12 s) were used. In heating in water bath process, samples were held in water bath at 90°C, until they reached 40, 60 or 80°C. After the pretreatments, natural colorant extraction was done. In spinach extracts, ß-carotene, chlorophyll-a, chlorophyll-b and total chlorophyll analyses, in tomatoes extracts, ß-carotene, lycopene and lutein analyses were done. In addition total solid content, pH and titratable acidity of the spinach and tomato samples were also determined.In ß-carotene extraction from spinach, the highest increase in extraction yield (19,65%) was obtained by heating in water bath process (80°C). The increase in extraction yield for chlorophyll-a, chlorophyll-b or total chlorophyll extractions was 14,90%, 12,55% and 13,72%, respectively, by the electroplasmolysis treatment (60V/cm-8s). In ß-carotene and lycopene extraction from tomatoes, the highest increase in extraction yield was obtained by electroplasmolysis treatment (80V/cm-4s), with the yield of 139,14%, 112,4%, respectively. A negative linear correlation existed between the pH value and relative efficiency of ß-carotene extraction of the tomato and spinach samples treated by electroplasmolysis.