Antimicrobial and functional properties of the proteins extracted from lemon, orange and grapefruit seeds press meals

The aim of this study was to determine the antimicrobial activities and functional properties of the proteins extracted from lemon (Citrus limon var. Kutdiken), orange (Citrus sinensis var. Dortyol) and grapefruit (Citrus paradisi var. Beyaz) seeds press meals. The ethanolic extracts of the proteins showed around 6.3-15.8 mm inhibition zones against some foodborne pathogenic bacteria. Although this range was 3-4 fold lower than the commercial antibiotic disk (sulbactam cefoperazone, 10.5 mu g), it still indicates presence of some antimicrobial activity. Likewise, the minimum inhibition concentration values were determined against the same bacteria. Although some pathogens were not inhibited at highest used concentration (5%) of protein ethanolic extracts, some extracts even were effective at 0.16-0.63% concentration levels. Hence, these extracts could inhibit the growth of some pathogenic bacteria. These citrus seed protein extracts exhibited good water and oil holding capacities and some foaming abilities, although their emulsification properties were lower. Overall, citrus seed proteins could be used in food products or other areas for their antimicrobial and functional properties.