Formation of Zinc‐Chlorophyll‐Derivative Complexes in Thermally Processed Green Pears (Pyrus communis L.)

Abstract

The formation of zinc-chlorophyll-derivative complexes was investigated in peels-on green D'Anjou pears when subjected to blanching in zinc ion solution (1300, 2600, and 0 ppm) at 94 degrees C for 6, 12, or 18 min and then canning at 94 degrees C for 20 min. The peels removed from the pears were freeze-dried and ground into powders in liquid nitrogen for pigment extraction using ethyl ether. The visual absorption of the extracts was measured using a spectrophotometer along with identification and quantification of chlorophyll derivatives using reverse-phase HPLC method. Furthermore, pears with or without the peels were blanched in 2600 ppm of zinc solution for 12 min following the canning process in 10 degree Brix syrup solution. Total antioxidant (TA) and total phenolic content (TPC) of the pear flesh and peels were evaluated using Folin-Ciocalteu's phenol and 1,1-diphenyl-2-picrylhydrazyl assays. Thermal processing destroyed chlorophylls on pear peels, in which pheophytins were found to be the major degraded compounds while an insignificant amount of pyropheophytins was also formed. In zinc blanched peels, Zn pheophytins a was the dominant green compound, and its amount increased about 100% and 144.4% in peels blanched in 1300 ppm zinc solution for 6 and 12 min, respectively. When blanching peels in 2600 ppm zinc solution for 6 and 12 min, the pigment increased about 118% and 242%, respectively. Significant reductions in TA and TPC were found on the peels of zinc treated pears, but the overall TA and TPC of whole fruits were not significantly affected by the treatments.

Modeling the inhibitory effects of zinc chloride on table olive related yeasts

“…Yeasts' demand for zinc is immediate from the initial stages of fermentation. Nicola et al (2009) showed that zinc uptake by yeasts in wine fermentations was very rapid, and all zinc was removed from the medium within the first 2 h.…”

“…In the yeast Saccharomyces cerevisiae, zinc is estimated to be required for the function of nearly 3% of proteome (Böhm, Frishman, & Mewes, 1997). In fact, the lack of this transition metal can dramatically influence yeast fermentation performance resulting in impaired or "sluggish" fermentations because zinc may not be bioavailable to yeast cells due to chelation with proteins or polyphenols (Nicola, Hall, Bollag, Thermogiannis, & Walker, 2009;Walker, 2004). Yeasts' demand for zinc is immediate from the initial stages of fermentation.…”

Biophysical and Biochemical Markers of Metal/Metalloid-Impacts in Salt Marsh Halophytes and Their Implications

“…Hence, the formation of minor proportions of heavy metal-substituted Chl relative to the total Chl may already inhibit photosynthesis completely, affecting the overall cell bioenergetics and redox homeostasis (Küpper et al, 2002). This substitution effect is rather well known and was already described in algae (Küpper et al, 1996) and in higher plants (Ngo and Zhao, 2007;Santos et al, 2014Santos et al, , 2015.…”

Effect of Maillard Reaction Products (MRP) on Chlorophyll Stability in Green Peas

“…Heat induced loss of green colour is a consequence [15] of both chlorophyll a and b degradation. In the present study, the effect of MRP on chlorophyll stability is more when compared to the stability of chlorophyll II b. formation of Zinc-chlorophyll derivative complexes in thermally processed green pears was studied [16]. The zinc ion reactions with chlorophylls lead to the formation of zinc chlorophyll complex, Zn pheophytin a and a' compounds contributing to the green colour of thermally processed green peas.…”