Background: Chronic kidney disease (CKD) is prevalent in
New Zealand and disproportionately affects Māori, underscoring the need for
culturally anchored dietary strategies. CKD guidelines recommend limiting
potassium to reduce hyperkalaemia risk and sodium to support blood pressure
and proteinuria control. Boil-up, a traditional Māori one-pot meal of meat,
root vegetables, and greens, can elevate dietary K⁺ and Na⁺ due to K-rich
greens and salted bones. Accordingly, this study aimed to test a culturally
grounded adaptation (adding intact Basmati rice in mesh bags during
simmering) to harness hydrocolloid-mediated cation partitioning, reducing
mineral (particularly K⁺) content in the served meat/vegetable portion while
preserving the dish’s cultural integrity.
Methods:Standardised boil-up was prepared with intact
Basmati rice (0, 30, 60, 100 g) added during the final 30 min of simmering.
Minerals (K⁺, Na⁺, and Ca²⁺) in the served food and recovered rice were
quantified by MP-AES. Proximate composition was also measured. Data are
presented as mean±SEM (n=3). One-way ANOVA with Tukey’s post-hoc tested
treatment effects (p < 0.05), with effect sizes (η²) were reported.
Results and Mechanism:Mineral reductions scaled with rice
amount (p < 0.05). At 100 g, for example, K⁺ decreased by 40.2±2.0%, Na⁺
by 53.4±1.6%, and Ca²⁺ by 39.6±8.3%, with corresponding enrichment of cooked
rice. Effect sizes were large to very large, consistent with
hydrocolloid-driven cation partitioning into gelatinising starch. The
proximate analysis showed that carbohydrate content of the boil-up increased
with increasing the rice mass, as expected. Slight decrease in crude protein
was also observed, likely due to surface area-to-volume effect; i.e., each
grain is exposed to a greater volume of nutrient-rich cooking water in
smaller rice portions, resulting in higher nutrient absorption per gram when
data is normalised to per 100 g. As grains hydrate and starch gelatinises,
mineral-rich broth diffuses into the grain down a concentration gradient.
The hydrated starch matrix and viscous boundary layer from surface-leached
starch retard back-diffusion, enabling net K⁺/Na⁺/Ca²⁺ transfer.
Significance:This simple, culturally compatible cooking
step offers a household-level CKD strategy—substantially lowering K⁺ and Na⁺
exposure in the portion consumed by CKD patients while producing a
nutrient-enriched rice portion for other diners. By working within a
traditional food using intact grains and boiling, it supports cultural
acceptance and shared family meals without separate dishes.
Keywords:rice hydrocolloids; cation partitioning; dietary
potassium; sodium reduction; traditional Māori foods; CKD nutrition.