Vegetables and their by-products: total phenolic compound content, total flavonoids, and antioxidant activity

ABSTRACT There is an underutilization of bioactive compounds, given the losses and daily waste of vegetables throughout the entire production chain. Accordingly, the objective of this study was to quantify the content of phenolic compounds and antioxidant capacity in different parts of vegetables. Analyzes were performed on five vegetables (zucchini, eggplant, broccoli, green cabbage and green beans) from conventional cultivation. The levels of total phenolics, total flavonoids, and antioxidant capacity were obtained by spectrophotometric methods. Except broccoli, the analyzed by-products had levels of bioactive compounds and antioxidant capacity equal to or greater than the traditional parts of vegetable. Broccoli florets stood out with the highest levels of total phenolics (141.22 mg GAE/100 g), total flavonoids (137.38 mg CE/100 g) and antioxidant capacity (588.3 µmol TEAC/100 g). In contrast, the lowest levels were observed in zucchini pulp (25.44 mg GAE/100 g; 13.03 mg CE/100 g; 69.78 µmol TEAC/100 g). Therefore, the importance of full consumption of vegetables is reiterated. By-products can also be used to enrich preparations.

摘要：鉴于蔬菜在全产业链中存在损耗与日常浪费，其生物活性化合物 (bioactive compounds) 的利用仍存在显著不足。据此，本研究旨在量化蔬菜不同部位的酚类化合物 (phenolic compounds) 含量与抗氧化能力 (antioxidant capacity)。本研究对常规种植的5种蔬菜（西葫芦 (zucchini)、茄子 (eggplant)、西兰花 (broccoli)、绿甘蓝 (green cabbage) 与青豆 (green beans)）开展分析，通过分光光度法 (spectrophotometric methods) 测定了总酚 (total phenolics)、总黄酮 (total flavonoids) 与抗氧化能力的水平。除西兰花外，本次分析的蔬菜副产物 (by-products) 的生物活性化合物含量与抗氧化能力均达到或高于其传统食用部位。西兰花小花簇的各项指标均为最高：总酚含量达141.22 mg GAE/100g（没食子酸当量，Gallic Acid Equivalent）、总黄酮含量达137.38 mg CE/100g（儿茶素当量，Catechin Equivalent），抗氧化能力为588.3 µmol TEAC/100g（Trolox等效抗氧化能力，Trolox Equivalent Antioxidant Capacity）。与之相对，西葫芦果肉的各项指标均为最低：总酚含量25.44 mg GAE/100g、总黄酮含量13.03 mg CE/100g，抗氧化能力69.78 µmol TEAC/100g。因此，本研究再次强调了全株食用蔬菜的重要性，同时指出蔬菜副产物亦可用于强化各类食品制备。