Discoloration in Raw and Processed Fruits and Vegetables

Abstract

Discoloration in fruits and vegetables is reviewed in relation to the chemical and biochemical causes of black, brown, red, yellow, and green discolorations. In raw materials, only a limited understanding has so far been achieved of the internal black and brown discolorations. The biochemical signaling pathways triggered by wounding or chilling-storage, the nature of the enzymes and reactive oxygen species involved, and the identity of the phenolic compounds oxidized are areas where further information is desirable. In processed materials, a greater comprehension is needed of the role of ascorbic acid reactions in the browning of fruits and "pinking" of Brassicaceous vegetables, and more information is desirable on the structure and properties of the discoloring pigments in many products. It is concluded that a greater knowledge of these areas, and of the naturally-occurring constituents that can accelerate or inhibit the causative reactions, would lead to the development of more efficient methods of controlling fruit and vegetable discolorations.

Enzymatic Browning of Fresh-cut Galangal (Alpinia siamense K. Schum) and its Relationship to Oxidative Enzymes

“…The substrate specificities of both enzymes have been reported for numerous freshcut products, including chlorogenic acid and/or tyrosine for PPO in pre-peeled potato (Cantos et al, 2002;Thybo et al, 2006), and ferulic acid for POD in sweet potato (Leon et al, 2002). The visible colour shown on the wounded surface depends on the structure of the phenolic compounds and the nature of the oxidative enzymes (Adams and Brown, 2007;Toivonen and Brummell, 2008). Tyrosine and dopamine are oxidized to melanins, while catechin and chlorogenic acid are generated to produce brown pigments (Adams and Brown, 2007).…”

“…The visible colour shown on the wounded surface depends on the structure of the phenolic compounds and the nature of the oxidative enzymes (Adams and Brown, 2007;Toivonen and Brummell, 2008). Tyrosine and dopamine are oxidized to melanins, while catechin and chlorogenic acid are generated to produce brown pigments (Adams and Brown, 2007).…”

Polifenoloxidasa, fenoles totales y oscurecimiento de nopal verdura

“…These authors did not evaluate other variables such as ascorbic acid (reducing quinones), total phenols, or the content of PPO substrates, which can influence the development of darkening. It has been observed that the darkening of the fabric occurs when the ascorbic acid content is exhausted (Adams and Brown, 2007). Additionally, it indicated that ascorbic acid may inhibit PPO with decreasing pH of the cytosol (Yoruk and Marshall, 2003).…”

Analysis of the Cytotoxicity of Green Pigment Produced on the Surface of Roasted and Retorted Chestnuts Using Immune Cells and Gastrointestinal Cancer Cells

“…The chemical composition and quality of roasted chestnuts have been poorly studied. Morini and Maga (2) Adams and Brown (4) reported that green discoloration in raw and processed vegetables was not a common phenomenon; however, garlic products and cooked sweet potatoes could also develop green pigments. Kubec et al (5) reported that isoalliin of garlic is enzymatically cleaved to 1-propenyl-containing thiosulfinates in the disrupted tissue and that these compounds react with amino acids to produce green pigments.…”