Traditional processing techniques impacted the bioactivities of selected local consumed foods

Abstract

Epidemiological and clinical studies have evidenced the crucial role of vegetables and mushrooms for our health. Vegetables and mushrooms are usually cooked before consumption which induces many physicochemical changes in foods. A change in the phytochemical content might alter the health benefits of the food. In this regard, the impact of domestic cooking particularly boiling, steaming and stir-frying at different time intervals (under-cooked, well-done and overcooking) on the phenolic content and antioxidant potential of locally grown Allium cepa L., Brassica chinensis L., Pleurotus sajor-caju and Moringa oleifera Lam leaves and pods were investigated. The anti-proliferative effects of the fresh and cooked vegetables were assessed on the hepatocellular carcinoma (HepG2) cell line. The results demonstrated a general increase in the phenolic content of A. cepa, P. sajor- caju, M. oleifera leaves and pods, but a decrease in B. chinensis after cooking. Both the raw and the cooked vegetables and mushroom demonstrated notable free radical scavenging abilities, potent ferric reducing antioxidant power and strong iron chelating activity across the different processing methods. Cooking significantly increased reducing potential of M. oleifera leaves and P. sajor-caju, while a significant decline was observed for B. chinensis and M. oleifera pods after thermal treatments. Boiling and stir-frying caused significant loss in the chelating potential of B. chinensis (p<0.05). In addition, cooking enhanced the anti-proliferative properties of B. chinensis, P. sajor-caju and M. oleifera leaves against liver cancer cells. The present data provide a new insight into the influence of conventional cooking methods on locally cultivated foods, highlighting the importance of choosing the appropriate processing technique to maximize bioaccessibility of the beneficial bioactive compounds.