Oxalic acid (C 2 O 4 2− ) is a component of many commonly eaten foods and is of interest as a result of its antinutritive properties. Table beet, a vegetable crop grown for both its roots and leaves, is considered by the National Kidney Foundation
Amy K. Freidig and Irwin L. Goldman
Peiyan Li, Xiaolin Zheng, Md. Golam Ferdous Chowdhury, Kim Cordasco and Jeffrey K. Brecht
), but exhibited no substantial differences in internal CI symptoms and fruit decay at the end of storage ( Fig. 2 ). Fig. 1. Effect of oxalic acid (OA) on external chilling injury (CI) symptoms index (0 to 4 scale) and fruit firmness index (1 to 5 scale
have a greater amount of oxalic acid than most crops. Oxalic acid is an organic acid present in fungi, algae, lichens, higher plants, and animals, including humans ( Oke, 1969 ) formed as a secondary metabolite of vitamin C ( Hodgkinson, 1977 ). Oxalic
Seth DeBolt, Renata Ristic, Patrick G. Iland and Christopher M. Ford
chromatography (HPLC) separation of tartaric, malic, and oxalic acids was achieved using a Prevail Organic Acid column 250 × 4.6 mm, 5-μm (Alltech Associates, Deerfield, IL); the mobile phase was 25 m m KH 2 PO 4 adjusted to pH 2 with phosphoric acid at a flow
Martin P.N. Gent
composition were determined from dried samples hydrolyzed in sulfuric acid and hydrogen peroxide as described previously ( Gent, 2012a ). Nitrate, phosphate, malic and oxalic acids, amino acids (except proline), and soluble sugars were extracted and analyzed
Yu Wang, Haobo Yang, Shuai Zhong, Xin Liu, Tong Li and Chengwen Zong
in our study: oxalic acid, citric acid, shikimic acid, vitamin C (ascorbic acid), L-malic acid, D-quinic acid, fructose, glucose, sucrose [chromatographically pure (Beijing TanMo Quality Inspection Technology Co., Beijing, China)], methanol
Xiaoling He, Susan C. Miyasaka, Maureen M.M. Fitch, Sawsan Khuri and Yun J. Zhu
, 2009). OxO was first isolated and characterized from wheat ( Triticum aestivum ) ( Lane et al., 1993 ). It catalyzes the oxidation of oxalic acid by molecular oxygen to form carbon dioxide and hydrogen peroxide (H 2 O 2 ). Researchers have found that
J.C. Beaulieu, J.M. Lea, G. Eggleston and Z. Peralta-Inga
Markedly higher average sucrose (58.1%) was recovered from mesocarp tissue of six orange-flesh cantaloupe (Cucumis melo L.) genotypes over three seasons compared to glucose (17.5%) and fructose (25.6%). A significant decrease in sucrose concentration was observed in the fall for all six genotypes, and the glucose (21.2%) and fructose (33.5%) ratios were also higher in the fall; markedly different than the spring fruit averages. The female inbreds had significantly (P = 0.05) lower glucose, fructose, sucrose, and total sugars than the commercial hybrids. Compared to the male and female inbreds, commercial hybrids had significantly (P = 0.05) higher concentrations of fructose, sucrose and total sugars, but not glucose. Two refractometric digital measures of °Brix (°Brix-At and °Brix-II) in homogenized slurries were positively correlated (r = 0.914; P ≤ 0.001), and were also correlated with total sugars (r ≥ 0.839) and sucrose (r ≥ 0.752). °Brix of cubes (°Brix-cube) was significantly correlated with sucrose and total sugars (r ≥ 0.627). Total sugar was positively correlated with sucrose (r = 0.843; P ≤ 0.001). Eastern-type U.S. melons had significantly (P = 0.05) higher °Brix-cube and °Brix-At compared to U.S. western shipper-types. Female inbreds were significantly (P = 0.05) lower in mean °Brix (all three measures) compared to the hybrids and male inbreds, and female inbreds had higher pH than the male inbreds. Western shippers had significantly (P = 0.05) higher pH compared to eastern genotypes. The predominant organic acid in all six genotypes was succinic acid, generally followed by oxalic, citric/isocitric, then malic acid. Succinic acid recovery was significantly higher in all six genotypes harvested in the fall, compared to spring. Eastern genotypes had significantly (P = 0.05) lower organic acids compared to western genotypes. Results indicate that maternal inheritance appears to confer lower sugar accumulating capacity and higher pH, which, is associated with vacuolar acid invertase (AI) and hexose balance. Breeding programs should focus on hybrid vigor derived through accentuating homozygous female inbreds with lower pH and higher capacity for sucrose accumulation, as well as morphological and agronomic traits often carried in the female line.
Michael Wisniewski and Glen Davis
The pit membrane of xylem parenchyma of peach plays an important role in deep supercooling. Enzyme hydrolysis of xylem tissue indicated that the pit membrane is rich in pectin. The objective of the present study was to determine if removal of calcium from the cell wall would effect deep supercooling by loosening the cell wall. Current year shoots of `Loring' peach were infiltrated with oxalic acid, EGTA, or sodium phosphate buffer for 24-48 hours and then prepared for either ultrastructural analysis or differential thermal analysis. The use of 5-50 mM oxalic acid resulted in a distinct reduction in the size of the low-temperature exotherm (LTE) with increasing concentration. Oxalic acid also produced a loosening and swelling of the pit membrane. The use of EGTA (100 mM) or NaP04 (150 mM) produced only a slight shift in the LTE to warmer temperatures when compared to fresh tissues. Heat treatments (30-100°C) also resulted in a gradual shift of the LTE to warmer temperatures. The data indicate that cross-linking of pectins may play a role in defining the pore structure of the pit membrane and that this area of the cell wall plays an integral role in deep supercooling of peach wood.
Henry D. Schreiber, Timothy Berry and Nam Trant
The sepals of many hydrangea cultivars change color from red in basic/neutral soil to blue in acidic soil. This change is generally attributed to Al(III) becoming mobile in acidic soils, allowing it to be absorbed through the roots as a citric acid complex; the ion of Al(III) then forms a blue complex in the sepals with an anthocyanin that is red in the absence of Al(III). This study investigated selected metal ions that might also result in similar color changes in hydrangea sepals. Model anthocyanins such as cyanidin and delphinidin glucoside readily formed blue complexes with metal ions with a high charge/size ratio [that is: Mo(VI), U(VI), and Zr(IV), in addition to Al(III)]. The anthocyanins only formed weak complexes with Fe(III) and Ga(III), and no complexes with Mg(II) and Mn(II). In order for the color change to occur in the sepals, though, the hydrangea must first be able to selectively concentrate the metal ion in the plant from the soil as a complex with citric or oxalic acid. The complexation of Al(III) with the organic acid is shown by the measurement of the heat of solution of citric and oxalic acid in Al(III) solutions as half that of the acids in just water. The presence of Al(III) also enhanced the solubility of oxalic acid in water. Mo(VI) likewise enhanced the organic acid's solubility, while Fe(III), Fe(II), and U(VI) did not appreciably affect the solubility. Mo(VI) and similar ions may be candidates to artificially induce bluing of hydrangea sepals, instead of the current use of Al(III).