Insoluble Oxalate Research Articles

Developing precipitation modes for preventing the calcium-oxalate contamination of sugar beet pectins

Effects of precipitation modes on the co-precipitation of insoluble oxalates particles during the purification of sugar beet pectins (SBP) from the extract were investigated. It was observed that soluble oxalate ions formed insoluble oxalate salts with calcium and precipitated with pectins during ethanol precipitation as pH of the medium increased and the solvent changed from water to ethanol–water mixture. Comparison among the employed precipitation methods revealed that both the dialysis–ethanol-precipitation and metal precipitation effectively prevented the calcium-oxalate contamination of SBP. Emulsifying properties of DEPP, EPP and MPP were also studied. It was observed that DEPP performed better than the remainder with respect to emulsifying ability. Based on these results, we concluded that the dialysis–ethanolic-precipitation can be a suitable method for improving the purity as well as emulsifying properties of the resulting pectins.

Calcium and Oxalate Contents of Curly Leaf (<i> Petroselinum crispum</i>) and Flat Leaf (<i> P. crispum var. neapolitanum </i>) Parsley Cultivars

The total, soluble and insoluble oxalate contents of the leaves and stems of curly leaf (Petroselinum crispum) and flat leaf (P. crispum var. neapolitanum) parsley cultivars were extracted from fresh tissue and measured using HPLC chromatography. There were no significant differences between the total and insoluble oxalate contents of the leaves between the flat leaf and curly leaf cultivars. There was a small difference (P < 0.05) between the soluble oxalate contents of the leaves of the two cultivars. The mean total, soluble and insoluble oxalates of the leaves of the two cultivars were 1137.0, 177.9 and 959.3 mg/100 g dry matter (DM), respectively. The mean total, soluble and insoluble oxalate contents of the stems were 1680.7, 386.2 and 1294.5 mg/100 g DM, respectively, and these were significantly higher than the mean values for the leaves of the two cultivars. Insoluble oxalate made up a mean of 77.0% of the curly leaf stems and leaves compared to a mean of 84.4% found in the flat-leaved cultivar. Unavailable calcium, that is, calcium bound to oxalate as insoluble oxalate, made up a mean of 26.9% of the total calcium in the leaves of both cultivars while the unavailable calcium made up 45.0% of the total calcium in the stems of the two cultivars. Overall, the oxalate contents of both parsley cultivars are relatively high, on a dry matter basis, but their overall contribution to dietary intake is likely to be quite small as parsley is an herb that is only used in small amounts to garnish foods.

Effect of Calcium Concentration in Growth Medium on Oxalate Content and Evaluation of the Role of Guttation in the Regulation of Oxalate in Eddo

The effects of calcium concentrations in the growth medium on oxalate content of leaf blades, petioles and corms and the involvement of guttation in the regulation of oxalate homeostasis were investigated in eddo (Colocasia esculenta (L.) Schott var. antiquorum Hubbard & Rehder). The plants were grown hydroponically in solutions containing 0 mM calcium, 1 mM calcium nitrate (control), 15 mM calcium nitrate or 15 mM calcium chloride. Total oxalate content (soluble plus insoluble) of leaf blades, petioles and corms did not differ with the calcium concentration in solutions containing 1 mM or 15 mM calcium nitrate or 0 mM calcium. The soluble oxalate content of these parts decreased as the calcium concentration of the solution was increased. Solutions containing 15 mM calcium nitrate or 15 mM calcium chloride gave a significantly lower proportion of soluble oxalate content to total oxalate content in each part, especially in leaf blades than 0 mM calcium or 1 mM calcium nitrate. In contrast, a positive correlation was found between insoluble oxalate content and calcium concentration in the solution. These results demonstrate that high calcium concentrations in the growth medium reduce soluble oxalate content of the plant. Soluble oxalate was detected in eddo guttation fluid. Soluble oxalate content in this fluid (mg mL−1) and the amount of soluble oxalate exuded by guttation (mg leaf−1 night−1) were significantly lower in the solutions containing 15 mM calcium than in those containing 0 mM and 1 mM calcium. These results indicate that guttation may affect the concentration of soluble oxalate in the plant bodies although not strongly contributing to a decrease in soluble oxalate content in eddo grown under high calcium conditions.

Tracing intracellular localization and chemical forms of copper in Elsholtzia splendens with cluster analysis.

Copper (Cu) accumulation in soils is becoming a major environmental problem. Elsholtzia splendens, a Cu-tolerant plant growing in Cu mine areas, can accumulate high levels of Cu. This study develops a systematic method of detecting the intracellular localization and different chemical forms of Cu to comprehensively understand the mechanisms involved in Cu tolerance and detoxification of E. splendens. Various chemical forms of Cu were absorbed by E. splendens, the highest proportion of which was stored in its cell walls (68%) and vacuoles (42%). Most of the Cu in the roots, stems and leaves were extracted by 2% hydrate acetic acid (HAc) in controls. The distribution characteristics of Cu, particularly in the roots, were closely related to the Cu tolerance of E. splendens. In addition, the binding capacity of Cu to soluble salts or proteins decreased and its binding capacity to insoluble oxalate increased with the increasing Cu supply. These results indicated that Cu ions were integrated with compounds of low bioavailable, such as undissolved phosphate or oxalate, which contributed to the metal tolerance and detoxification of E. splendens. Cluster analysis, based on Cu abundance levels, reveals that correlations exist between the chemical forms of Cu and their intracellular locations, which in turn indicates a relationship between their migration activity and toxicity.

Effect of Kimchi Fermentation on Oxalate Levels in Silver Beet (Beta vulgaris var. cicla).

Total, soluble and insoluble oxalates were extracted and analyzed by high performance liquid chromatography (HPLC) following the preparation of kimchi using silver beet (Beta vulgaris var. cicla) stems and leaves. As silver beet contains high oxalate concentrations and consumption of high levels can cause the development of kidney stones in some people, the reduction of oxalate during preparation and fermentation of kimchi was investigated. The silver beet stems and leaves were soaked in a 10% brine solution for 11 h and then washed in cold tap water. The total, soluble and insoluble oxalate contents of the silver beet leaves were reduced by soaking in brine, from 4275.81 ± 165.48 mg/100 g to 3709.49 ± 216.51 mg/100 g fresh weight (FW). Fermenting the kimchi for 5 days at 19.3 ± 0.8 °C in 5 L ceramic jars with a water airtight seal resulted in a mean 38.50% reduction in total oxalate content and a mean 22.86% reduction in soluble oxalates. The total calcium content was essentially the same before and after the fermentation of the kimchi (mean 296.1 mg/100 g FW). The study showed that fermentation of kimchi significantly (p < 0.05) reduced the total oxalate concentration in the initial mix from 609.32 ± 15.69 to 374.71 ± 7.94 mg/100 g FW in the final mix which led to a 72.3% reduction in the amount of calcium bound to insoluble oxalate.

Manufacture of a Low Oxalate Mitsumame-Type Dessert Using Rhubarb Juice and Calcium Salts

Rhubarb (Rheum rhabarbarum) juice was used to make a Japanese soft mitsumame-type dessert sweet. The dessert was prepared from extracted rhubarb juice, which was cooked with sugar, agar and guar gum, then allowed to set in sweet moulds. The total, soluble and insoluble oxalates were determined in the ingredients and the final products using HPLC chromatography. To reduce the soluble oxalate content of the dessert while retaining the colour and taste of the final product, increments of CaCl2 and CaCO3 were added to the test dessert mixes. The addition of CaCl2 reduced the pH from 3.55 ± 0.03 to pH 3.09 ± 0.02 while addition of CaCO3 increased the pH from 3.55 ± 0.03 to 4.96 ± 0.01. In both cases, the incremental addition of calcium reduced the soluble oxalate content of the sweets by converting it to insoluble oxalate.

Kinetics of Calcium Oxalate Reduction in Taro (Colocasia Esculenta) Corm Chips during Treatments Using Baking Soda Solution

The oxalates content has caused limited utilizations of taro (Colocasia esculenta) as a food material. The insoluble oxalates, especially needle like calcium oxalate crystal may cause irritation, and swelling of mouth and throat. Removal of oxalates in food can be done by physical processes, such as soaking, boiling, and cooking or chemical process by converting them into soluble phases. The purpose of this research were to investigate the effects of baking soda concentration (0-10% w/w) and temperatures (70-97°C) on the reduction of calcium oxalate content in the taro corm chips and to develop a kinetic model of that process during boiling in baking soda solution. The kinetic model development was done by considering the dissolution of calcium oxalate, chemical reaction and thermal degradation that take place during boiling. The experimental results showed that increasing of baking soda concentration and temperatures were found to increase the reduction of calcium oxalate in the taro corm chips. Based on the product's functional properties, the best condition for calcium oxalate reduction was soaking in 10% w/w baking soda solution for 2hours followed by boiling at 90°C for 60minutes. The kinetic modeling concluded that the calcium oxalate reduction was found to follow a pseudo first order reaction. The modeling results showed that the model is able to represent the phenomena quite well with the apparent reduction rate constant, k = 15.77 Exp (21.239)/RT minute-1.

Late diagnosis of primary hyperoxaluria type 1 despite recurrent kidney stones and positive family history

Primary hyperoxaluria type 1 (PH1) is the most common form of primary hyperoxalurias. It results in increased synthesis and subsequent urinary excretion of the metabolic end product oxalate and the deposition of insoluble calcium oxalate in the kidney and urinary tract. Individuals with PH1 are at high risk for recurrent nephrolithiasis, nephrocalcinosis, and end-stage renal disease (ESRD). A 13 years-old female presented with fatigue, headache, nausea, vomiting, anorexia, renal colic. Initial clinical and laboratory investigations revealed ESRD and the patient was initiated on hemodialysis. Family history of PH1 and a history of recurrent kidney stones for 4 years was elicited. Subsequently, PH1 was confirmed by, physical examination, medical history, family history, laboratory tests, ultrasound imaging, X- ray, CT scanning and renal biopsy. As this disease is no longer rare in Jenin District of Palestine where this patient was seen, delayed diagnosis can not be justified. In conclusion, early diagnosis and effective treatment of PH1 in areas with high prevalence, such as the Jenin District of Palestine, is warranted as it may delay the progression towards ESRD or systemic oxalosis.

A New Method for the Analysis of Soluble and Insoluble Oxalate in Pulp and Paper Matrices

A novel method has been developed for determining soluble and insoluble forms of oxalate in pulp and paper samples by ion chromatography. Methanesulphonic acid is used to dissolve insoluble oxalate, and total oxalate is then determined by ion chromatography with suppressed conductivity detection. Soluble oxalate is determined directly by ion chromatography, without prior chemical treatment. Insoluble oxalate is obtained by difference. The method was applied to samples of pulp, process liquors, filtrates, and scale deposits from kraft mills. In kraft mills, considerably higher levels of oxalate were found in the Eop samples compared to those in the brownstock and D0 samples. In both brownstock and Eop samples, oxalate was mainly present in soluble form, whereas the D0-stage contained relatively higher levels of insoluble oxalate.

Effects of phytate and minerals on the bioavailability of oxalate from food

Phytate and mineral cations are both considered as important dietary factors for inhibiting the crystallisation of calcium oxalate kidney stones in susceptible individuals. In this paper, the phytate and mineral composition of whole bran cereals (wheat, barley and oat) and legumes were determined together with their soluble and insoluble oxalate concentrations in order to investigate the effects on oxalate solubility. The oat bran sample had the highest soluble oxalate concentration at 79±1.3mg/100g, while total and soluble oxalate concentrations in the food samples studied range from 33 to 199mg/100g and 14 to 79mg/100g, respectively. The phytate concentration was in the range from 227 to 4393mg/100g and the concentrations of cations were in the range 54–70mg/100g for calcium, 75–398mg/100g for magnesium, 244–1529mg/100g for potassium and 4–11mg/100g for iron. Soluble oxalate concentration did not increase in proportion to total oxalate, and the phytate concentration in all foods was sufficient to contribute to an increase in soluble oxalate concentration by binding calcium.

Oxalate content of Indian spinach dishes cooked in a wok

Total, soluble and insoluble oxalate contents of four different traditional wok-cooked dishes, based on spinach (palak) with added spices, were determined by HPLC chromatography. Four different palak dishes were cooked with three different combinations of spices. During the final stage of cooking an Indian cottage cheese, paneer, was added to one dish. Each combination was cooked for 15min in a wok to give the saak dishes while other dishes containing the same combination of Indian spices and paneer were cooked for a further 10min, until they were dry to give the saak bhaji dishes. Cooking spinach in a wok to make saak and saak bhaji resulted in mean reductions of 17.6% of soluble oxalate compared to the raw spinach, soluble oxalate reductions were not observed in the plain palak saak dishes while the addition of ginger gave a mean increase in the total and soluble oxalates (23% and 43%, respectively) compared to palak saak. Addition of paneer, an Indian cheese product resulted in an overall reduction in total and soluble oxalates by dilution. Palak, palak saak and palak saah with ginger contained a mean of 1.7 and 6.9g soluble oxalate/standard serving respectively while the two palak paneer dishes contained a mean of 0.6g soluble oxalate/standard serving.

Total, Soluble and Insoluble Oxalate Contents of Ripe Green and Golden Kiwifruit.

Three bulk samples of two different cultivars of kiwifruit, green (Actinidia deliciosa L.) and golden (Actinidia chinensis L.) were bought ripe, ready to eat from a local market. The aim of the study was to determine the oxalate composition of each of the three fractions of kiwifruit, namely skin, pulp and seeds. The pulp consisted of 90.4% of the edible portion of the two cultivars while the skin and seeds made up a mean of 8.0% and 1.6% respectively. Total oxalate was extracted with 2.0 M HCL at 21 °C for 15 min and soluble oxalates extracted at 21 °C in water for 15 min from each fraction. The total and soluble oxalate compositions of each fraction were determined using ion exchange HPLC chromatography. The pulp of golden kiwifruit contained lower amounts of total oxalates (15.7 vs. 19.3 mg/100 g FW) and higher amounts of soluble oxalates (8.5 vs. 7.6 mg/100 g FW) when compared to the green cultivar. The skin of the green cultivar contained lower levels of insoluble oxalates (36.9 vs. 43.6 mg/100 g FW), while the seeds of the green cultivar contained higher levels of insoluble oxalates 106.7 vs. 84.7 mg/100 g FW.

Bioavailability Analysis of Oxalate and Mineral Content in Selected Edible Mushrooms

Total, soluble, insoluble oxalate and mineral content of 20 edible mushrooms were measured using spectroscopic and enzymatic methods. Total oxalate content ranged from 45 (Hericium erinaceus) to 104 (Morchella conica), mg/100 g dry matter (DM), while the soluble oxalate levels ranged from 34 (Lactaius delicious) to 65 (Phellinus florida) mg/100g DM but not detected in Hericium erinaceus, Sparassis crispa, Geastrum arinarius, Boletus edulis, Helvella crispa, and Ganoderma lucidum respectively and very low in Lactaius delicious (34), Russula brevepis (35), and Cantharellus clavatus (37) mg/100g DM. The Ca, P, K and Mg content showed range of 1.35-12.56 mg/g for Ca, 1.22-3.82 mg/g for P, 15.4-25.4 mg/g for K and 1.19-4.71 mg/g for Mg. Overall, the percentage of soluble oxalate content of the selected mushrooms ranged from 34 to 65% of the total oxalate content which suggests that, the selected edible mushrooms presents no risk to people liable to kidney stone formation while other foods like some spices and vegetables can supply significant amounts of soluble oxalates and therefore should be used in moderation as good vegetable, which might be important for human nutrition.

Investigation of Oxalate Levels in Sorrel Plant Parts and Sorrel-Based Products

The oxalate content of the leaves and stems of green and variegated cultivars of sorrel (Rumex acetosa) were extracted and measured using HPLC chromatography. The larger, more mature leaves of both cultivars contained higher levels of total, soluble and insoluble oxalates. The stems also contained appreciable levels of oxalates. The mean soluble oxalate content of the variegated leaves was 14.7%, which was significantly higher than found in the leaves of the green-leaved cultivar (11.9%). The proportion of soluble oxalate to total oxalate in the stems ranged from 12.7% to 24.4% for both cultivars. Sorrel sprouts contained a much higher proportion of soluble oxalates than the green sorrel leaves but were similar in oxalate content to the variegated leaves. Pesto and soup made from sorrel leaves retained their characteristic sour taste despite containing much lower levels of oxalates. The levels of oxalates in sorrel leaves were high and it was recommended that the leaves should be consumed occasionally as a delicacy because of their unique taste rather than as a significant part of the diet. However, the products made from sorrel leaves were less of a problem as they contained lower levels of oxalates.

Effects of UV-B Radiation on Oxalate Content of Silver Beet Leaves

Silver beet (&lt;em&gt;Beta vulgaricus &lt;/em&gt;var. &lt;em&gt;cicla&lt;/em&gt;) a common vegetable in New Zealand is known to contain high levels of oxalates in the leaves. Silver beet plants were grown in afield trial under glass and perspex sheets which filtered sunlight reaching the plants. After eight weeks of growth, the plants were harvested and the total, soluble and insoluble oxalate content of the leaves of the plants grown under the two filter treatments and a no-frame control were measured. Perspex allowed the transmission of UV-A, UV-B and photosynthetically active radiation (PAR), whereas glass excluded UV-B radiation. No significant differences between the perspex treatment and the no-frame control were observed when the data was compared on a wet matter (WM) or dry matter (DM) basis Shielding the growing plants with glass significantly reduced the total oxalate and soluble oxalates to 83 and 84% respectively when compared to the perspexand no-frame treatments.

Decomposition of copper – amino acid complexes by oxalic acid dihydrate

A facile approach to the synthesis of some side-chain-protected amino acids via oxalic acid dihydrate as the copper sequestering reagent is presented. The copper in the amino acid complex reacted with oxalic acid dihydrate to form insoluble cupric oxalate, with the free amino acid released. Compared with conventional methods, this method is convenient, inexpensive, and environmentally friendly.

Effect of simple processing methods on oxalate content of taro petioles and leaves grown in central Viet Nam

This study investigated the total, soluble and insoluble oxalate contents of the petioles and the leaves from two different cultivars, Mon Cham (purple stem) and Chia Voi (light green stem), of taro (Alocasia odora) grown in central Viet Nam. These cultivars were processed by wilting for 18 h, resulting in an overall 5.9% reduction of soluble oxalates and washing in cold water for 5 min, resulting in a 26.2% reduction in soluble oxalate content. Soaking the petioles and the petioles and leaves for 10 h in water kept at 36–38 °C resulted in a mean 69.5% reduction in the soluble oxalate content of the raw tissues. Boiling for 60 min was the most effective way to reduce the soluble oxalate levels in the cooked tissue. A mean 84.2% reduction in soluble oxalate in the petioles and the petioles and leaves was achieved after boiling for 60 min while mean reductions of 62.1% were achieved when both materials were boiled for only 10 min.

Total and soluble oxalate content of some Indian spices.

Spices, such as cinnamon, cloves, cardamom, garlic, ginger, cumin, coriander and turmeric are used all over the world as flavouring and colouring ingredients in Indian foods. Previous studies have shown that spices contain variable amounts of total oxalates but there are few reports of soluble oxalate contents. In this study, the total, soluble and insoluble oxalate contents of ten different spices commonly used in Indian cuisine were measured. Total oxalate content ranged from 194 (nutmeg) to 4,014 (green cardamom) mg/100g DM, while the soluble oxalate contents ranged from 41 (nutmeg) to 3,977 (green cardamom) mg/100g DM. Overall, the percentage of soluble oxalate content of the spices ranged from 4.7 to 99.1% of the total oxalate content which suggests that some spices present no risk to people liable to kidney stone formation, while other spices can supply significant amounts of soluble oxalates and therefore should be used in moderation.

Oxalate Content of Stir Fried Silver Beet Leaves (Beta Vulgaris Var. Cicla) with and without Additions of Yoghurt

Total and soluble oxalic acids were extracted and analysed by HPLC chromatography following Asian cooking methods, which involved soaking, boiling and stir frying of silver beet (&lt;em&gt;Beta vulgaris &lt;/em&gt;var. cicla) leaves. Autumn-grown silver beet leaves contained 1658 ± 114 mg/100 g dry matter (DM) of total oxalates, 954 ± 49 mg/100 g DM of soluble oxalates and 704 ± 98 mg/ 100 g DM insoluble oxalates. Soaking and boiling before stir frying reduced the soluble oxalate contents to a mean of 455 mg/100 g DM. Addition of standard or low fat yoghurt following the pre-treatments of soaking, boiling, stir frying and soaking, boiling and stir frying further reduced the soluble oxalate content to a mean of 190.8 ± 49.8 and 227.5. ± 47.0, respectively, for the standard and low fat yoghurt mixes.

Effect of Cooking on the Oxalate Content of Selected Thai Vegetables

Total and soluble oxalate content levels were measured in thirteen selected vegetables purchased from a local market in Surin Province in the northeast of Thailand. Total oxalate contents of the leaves, shoots and roots of the fresh vegetables ranged from 249.5 ± 12.1 to 7597.9 ± 77.6 mg oxalate/100g dry matter (DM) while soluble oxalate content ranged from 205.0 ± 2.3 to 2677.6 ± 19.0 mg oxalate/100g DM. Very high levels of total oxalates were found in three of the selected Thai vegetables, Polygonum odoratum (7597.9 ± 77.6 mg/100g DM), Piper aurantaucum (7026.6 ± 76.9 mg/100g DM) and Limnophila aromatica (6179.0 ± 23.6 mg/100g DM). However, the soluble oxalate content of L. aromatica was low and the highest soluble oxalate contents of fresh vegetables were found in P. odoratum, P. aurantuacum and Neptunia oleracea at 2677.6 ± 19.0, 2152.2 ± 65.3 and 1640.8 ± 3.4 mg/100g DM, respectively. Boiling the vegetables reduced the soluble oxalate content between 30.4 and 65.0%. The insoluble oxalate levels increased in eleven of the cooked vegetables while small decreases were observed in L. aromatica and N. oleracea.