Apples ( Malus × sylvestris var. domestica ) are an important source of polyphenols (phenolic compounds) in the human diet ( Hertog et al., 1992 ) and a classic example of fruit susceptibility to enzymatic browning, which is a major problem for
The control of enzymatic browning of apple slices with papain is presented. Fresh apple slices dipped in a 1% Papain solution for 2 min did not brown for more than 12 hours at room temperature. Papain also gave good browning control of sliced pears. Further study indicated that polyphenoloxidase, a key enzyme involved in browning, was inactivated by this treatment.
Abstract
Heritabilities were estimated for 4 measures of bruise-induced enzymatic browning in peaches (Prunus persica L.) Batsch. Two were direct measures: intensity of the brown color (IB) and the diameter of the brown region (DB). Two were indirect measures: activity of polyphenyloxydase (PPO) and the concentration of polyphenols (PPC). The heritability of IB was moderately high (0.35 ± 0.04). That of DB was not significantly different from zero (0.08 ± 0.06). The heritability of PPC was reasonably high (0.38 ± 0.05), and that of PPO moderate (0.26 ± 0.04). Because the heritabilities of IB and PPC are about equal, the rate of reduction in IB resulting from selection on PPC should not be expected to be as great as that resulting from direct selection applied to IB. Thus, at present it appears that the direct measure of IB provides breeders with the best measure, among the 4 studied, of the susceptibility of seedlings to bruise-induced enzymatic browning.
Abstract
We established that surface browning in parsnips is due to enzymatic oxidation of phenolic compounds by an active polyphenoloxidase system. Potential browning was highest in the tissue immediately below the surface. The total phenolic content was lowest on the root surface and highest in the vascular cylinder region, whereas chlorogenic acid generally was uniformly distributed throughout the entire root. Enzyme activity was highest in the surface tissue and almost absent in the vascular cylinder. No direct relationships were found between the degree of browning and the parameters studied.
Rate of brown rot lesion development following inoculation with Monilinia fructicola (Wint.) honey varied within clingstone peach (Prunus persica (L.) Batsch) germplasm evaluated in 1990 and 1991. High levels of resistance were identified in selections derived from the Brazilian clingstone peach cultivar Bolinha. Resistance appeared to be limited to the epidermal tissue. No relation was detected between brown rot resistance and concentration of phenolic compounds or polyphenol oxidase activity in the susceptible California germplasm. An inverse relation was observed between disease severity and rating for phenolic-related discoloration when `Bolinha' derived selections were analyzed. A moderate positive correlation was observed for all germplasm tested between genotype means for phenolic content and enzymatic browning. Any causal relationship, if it exists, between phenolic content and brown rot resistance is obscured by an array of physical and chemical changes in the maturing fruit.
Abstract
Trees of ‘Redhaven’ peach (Prunus persica (L.) Batsch) were sprayed with 100 ppm gibberellic acid (GA) or 75 or 150 ppm (2-chloroethyl)phosphonic acid (ethephon) 21 or 46 days after full bloom and the ripe fruits were evaluated for enzymatic browning. Treated fruit had less browning than untreated fruit and fruit treated 46 days after bloom had less browning than fruit treated 21 days after bloom. Purees from ethephon treated fruit had higher pH values than those from GA treated fruit. Fresh weight of ethephon treated fruit varied with ethephon concentration and time of application. Polyphenoloxidase (PPO) activity and o-diphenol content were not affected by treatment. Multiple regression analysis indicated that 81% of the variation in browning was explained by variations in treatment, treatment application date, o-diphenol content, PPO activity and fresh weight.
enzymatic browning ( Eissa et al., 2006 ; Pma, 2006 ; Son et al., 2015 ). At present, the methods for controlling the browning of lotus root mainly include chemical treatment ( Kwon and Baek, 2014 ; Lu et al., 2007 ), modified atmosphere (MA) packaging
Abstract
Carrot and parsnip roots showed a sigmoidal increase in surface browning, total phenolic compounds, chlorogenic acid, and polyphenoloxidase activity over 7 days of suberization. Parsnip roots changed more rapidly and ended with higher levels than carrot roots. Total phenolic content of parsnips increased with depth of tissue; the reverse was generally true in carrots. In contrast, potential browning and enzyme activity decreased with depth of tissue in both root crops. The vascular cylinder had no detectable enzyme activity and little browning. However, after suberization, all tissues, regardless of their original composition, showed considerable synthesis of all compounds investigated. This study indicated that any damage to the root which stimulates the suberization process also accelerates surface browning and adversely affects market quality.
The main quality defect in fresh-cut potato is enzymatic browning that develops on the cut surfaces of the tissue. Peeling and slicing of tubers cause cellular disruption leading to decompartmentalization of substrates and enzymes ( Brecht et al
Abstract
Based on the occurrence or absence of browning in young shoot extracts, Citrus taxa can be classified into 2 phenotypes: browning and nonbrowning. Browning results from the enzymatic oxidation of phenolic substrate present in the browning taxa. The enzyme responsible for browning is polyphenol oxidase (ortho-diphenol oxidase, EC 1.10.3.1). Nonbrowning taxa lack the substrate(s) and have little or no polyphenol oxidase activity. Browning appears to be a dominant trait. It should be useful as a genetic marker and a taxonomic criterion.