Yield and Quality of Green Leafy Vegetables in Postharvest

Basil (Ocimum basilicum L.) is an aromatic herb, members of the Lamiaceae family, used extensively to add a distinctive aroma and flavour to food. The leaves can be used fresh or dried to use them as a spice. The cultivar displayed a wide diversity in growth habit, flower, leaf and stem colors, and aromas. Many of the cultivar belong to the “Sweet” basil group, as ‘Genovese’, ‘Italian large leaf’, ‘Napoletano’, and ‘Sweet’ dominating fresh and dry culinary herb markets (Simon et al., 1999).

Basil contains a wide range of essential oils rich in phenolic compounds (Simon et al., 1990; Phippen and Simon 2000) and a wide array of other natural products including polyphenols such as flavonoids and anthocyanins (Nakatani, 1997; Phippen and Simon 1998; Kahkonen et al., 1999).
In the sweet basil group are many green basil varieties, rich in a combination of linalool, methylchavicol and 1,8-cineole (Simon et al., 1990).

The main antioxidant activity from basil plants does not arise from their essential oils, but rather from other phenolics such as flavonoids in green basils and anthocyanins in purple basils (Juliani and Simon 2002).
Basil can not be kept for long periods after harvest, and the essential oil content and quality can be reduced during postharvest. The main cause of losses is endogenous, though external factors as chilling injury may contribute (Lange and Cameron, 1994, 1997). The cutting of vegetable provokes wound-induced physiological and biochemical reactions that shorten product storage life (Salveit, 1997).

These changes facilitate the water loss, and the enzymatic degradation of chlorophyll associated with tissue senescence or tissue browning (Cantwell and Reid, 1994; Philosoph-Hadas et al., 1994; Meir et al., 1997). Water loss in fresh vegetables results in wilted, dull appearance that reduces eye appeal and freshness. Prevent water loss means improves shelf life, appearance and desirability. It is prevented storing the product at low temperatures and at the high relative humidity. Furthermore, an increased peroxidase and lipoxygenase activities are responsible for tissue yellowing (Yamauchi and Watada, 1991).

Physiological changes following wounding include increased respiration and ethylene production, and accumulation of phenol compounds, natural substrates of oxidative enzymes (Brecht et al., 2004; Couture et al., 1993; Castaner et al., 1999).
Moreover, other indicator of nutritional quality of the vegetables is the ascorbic acid (AA). AA is a molecule of dietary importance to humans. A wide range of factors such as genotype, preharvest and postharvest conditions influence his content (Lee and Kader 2000).