Effect of blanching on mineral and oxalate content of spinach

Summary. Unblanched and blanched spinach were sampled from a factory line with conventional water blanchers. the samples were analysed for potassium, sodium, calcium, magnesium, phosphorus, nitrate and soluble and insoluble oxalate. the main results show that spinach takes up calcium from the water during blanching. This increase in calcium content of the spinach has a direct influence on the ratio between the soluble and insoluble form of oxalate. Loss of nitrate is higher than that of the other water soluble constituents. In a small trial, an attempt was made to increase the nutritional value of spinach by precipitation of all soluble oxalate through addition of excess of calcium chloride to processed, chopped spinach. However, a taste panel rated the enriched sample as inferior owing to its colour. A small blanching trial with tap, distilled and softened water showed that the amount of calcium in tap water has no such undesirable effect on colour.