engleski

Comparison of polyphenol content and antioxidative properties of fresh and processed Asparagus officinalis L.

Green asparagus (Asparagus officinalis L.) is a healthy edible vegetable, due to the fact it contains significant amount of polyphenols with antioxidant properties, is rich in fiber, and low in calories. Various studies have been carried out regarding polyphenol component of asparagus. Rutin and ferulic acid derivatives have been identified as major components, and the polyphenols seem to be unaffected by season or year to year variation, as well as storage. Asparagus has been identified as a source of bioactive compounds that decrease cholesterol levels and protect against cancer and cardiovascular diseases. Although various asparagus types were studied for polyphenol content, no reports in the literature characterized food processing waste products from asparagus. Also, most literature covers commercialy grown asparagus, while wild asparagus is less studied. In this study we want to: a) compare polyphenol profile and antioxidative properties of wild and cultivated asparagus, b) measure changes in polyphenol content and antioxidative properties occuring during cooking and freeze-storage of asparagus and c) determine useability of asparagus waste - cooking water and unedible plant parts - as added-value product. Wild green asparagus was collected in Primorsko-goranska county. Cultivated green asparagus was bought in a local supermarket, and originated from Spain. The samples were prepared fresh, blanched, and stored for 1 year at -20oC. Water after blanching was frozen at -20oC before analysis. Nonedible parts were stored at +4oC and extraction was carried out within 4 days. Polyphenol profile was determined with UPLC chromatography on C18 column (Zorbax) and quantified with gallic acid. Total polyphenols and total flavonoids were determined spectrofotometrically. Antioxidant properties were determined using DPPH and ABTS spectrofotometric methods. In our preliminary experiments, we found that: a) wild and cultivated Asparagus officinalis L. showed significantly different polyphenol UPLC profiles, b) no significant change in polyphenol profile was detected after 1 year sotrage at -20oC, c) remaining water after asparagus blanching from wild asparagus waste, but not cultivated asparagus waste, contained significant amount of polyphenols that could be used as added-value product.

asparagus; polyphenols; food processing; waste material

Potpora Sveučilišta u Rijeci br. 13.11.1.2.02