Soluble, Dialyzable and Ionic Calcium in Raw and Processed Skim Milk, Whole Milk and Spinach

Abstract

Chemical availability of calcium was measured with and without simulated digestion to determine processing effects. Available calcium was low in spinach and significantly higher in skim milk and whole milk, consistent with their known bioavailabilities. In nondigested processed milk it was significantly higher for whole milk than for skim milk. However, available calcium in digested whole milk was lower than in digested skim milk. Digestion increased available calcium in skim milk, dialyzable and ionic dialyzable calcium in whole milk and ionic calcium in spinach. Soluble and ionic soluble calcium were lowered in whole milk during digestion due to soap formation. Effects on % calcium were slight, but available calcium in nondigested skim milk was significantly lowered by processing. MATERIALS & METHODSAMOUNTS OF AVAILABLE CALCIUM in raw and processed skim milk, whole milk and raw and boiled spinach were compared. Available calcium included dialyzable (D), ionic dialyzable (ID), soluble (S) and ionic soluble (IS) calcium. D and S calcium included both ionic and bound calcium. Two chemical methods which each gave useful measurements determined available calcium: Dialysis measured D and ID calcium, and solubility measured S and IS calcium. Raw and commercially processed (homogenized and pasteurized) skim milk and whole milk were obtained from the UW-Madison Dairy Plant.Samples were held at 4°C overnight before analysis. Fresh spinach was purchased locally and homogenized with distilled water in a blender. A portion was processed by boiling for 20 min.

Oxalate Reduces Calcium Availability in the Pads of the Prickly Pear Cactus through Formation of Calcium Oxalate Crystals

“…These values were found to be similar to the 3.0 and 29.4% calcium bioavailability values determined for spinach and kale, respectively, in animal feeding trials (15). Thus, our findings along with the findings of other researchers (16)(17)(18)(19)(20)(21)(22)(23) support the usefulness of this in vitro protocol for assessing mineral bioavailability.…”

“…Samples of spinach and kale were used as controls for high- and low-calcium oxalate plants, respectively. The in vitro digestion and dialysis method has been utilized in numerous studies to assess the availability of various minerals and compounds in foods ( − ). On the basis of simply mineral composition, one would expect that nopales would provide the highest amount of available calcium, followed by spinach and kale, respectively.…”

Partition of Main and Trace Minerals in Milk: Effect of Ultracentrifugation, Rennet Coagulation, and Dialysis on Soluble Phase Separation

“…The procedures most widely used for the preparation of a suitable aqueous phase for determination of soluble components are analysis of rennet whey (Sindhu and Roy 1976b;O'Connor and Fox, 1977), high speed centrifuging (Sindhu and Roy, 1976a;Rajput et al, 1983;Polychroniadou and Vafopoulou, 1986), and different types of dialysis (Davies and White, 1960;Sindhu and Roy, 1973;Singh et al, 1989;Reykdal and Lee, 1991).…”

“…Leaving aside techniques of ultrafiltration (Davies and White, 1960;Brule ´and Fauquant, 1981;Papajova ´, 1982) which present a number of drawbacks for routine work, several methods of fractionation of the soluble and colloidal constituents have been applied. The procedures most widely used for the preparation of a suitable aqueous phase for determination of soluble components are analysis of rennet whey (Sindhu and Roy 1976b;O'Connor and Fox, 1977), high speed centrifuging (Sindhu and Roy, 1976a;Rajput et al, 1983;Polychroniadou and Vafopoulou, 1986), and different types of dialysis (Davies and White, 1960;Sindhu and Roy, 1973;Singh et al, 1989;Reykdal and Lee, 1991).…”

Iron bioavailability fromAmaranthus species: 1—In vitro dialysable iron for estimation of genetic variation

“…The small amount of plant material needed, the low cost (especially compared to animal studies) and the higher number of samples analysed per run favoured its applicability to the evaluation of plant material. This method also may be adaptable for the study of nutritional contribution of other plant minerals (Reykdal and Lee 1991) or materials (Latunde Dada 1991). The use of total Fe analysis for broad screening of total Fe content, combined with in vitro dialysable and soluble Fe analyses for more speciÐc screening of select high and low Fe lines, is a very efficient method for evaluation of genetic variability of Fe nutritional quality and identiÐcation of interesting species and lines for further study.…”