Hn. Larsen et al., Glycaemic index of parboiled rice depends on the severity of processing: study in type 2 diabetic subjects, EUR J CL N, 54(5), 2000, pp. 380-385
Objective: To study the influence of parboiling and the severity of the pro
cess on glycaemic and insulinaemic responses to rice in type 2 diabetes. Mo
reover, to examine changes in starch structure related to parboiling, which
may affect the metabolic responses and digestibility.
Design: Nine type 2 diabetic subjects ingested four test meals: white bread
(WB) and three meals of cooked polished rice of the same variety being non
-parboiled (NP), mildly traditionally parboiled (TP) and severely pressure
parboiled (PP). The participants ingested the test meals (50 g available ca
rbohydrates) on separate occasions after an overnight fast.
Setting: Outpatient clinic, Dept. Endocrinology and Metabolism, Aarhus Univ
ersity Hospital, Denmark.
Results: All three rice samples elicited lower postprandial plasma glucose
response (NP: 335 +/- 43; TP: 274 +/- 53; PP: 231 +/- 37 mmol/ 1*180 min.;
means +/- s.e.m.) than white bread (626 +/- 80; P < 0.001), within rice sam
ples PP tended to be lower than NP (P = 0.07). The glycaemic indices were:
NP: 55 +/- 5, TP: 46 +/- 8 and PP: 39 +/- 6, and lower for PP than NP (P <
0.05). The insulin responses were similar for the three rice meals, which w
ere all lower than that to white bread (P < 0.001). Differential scanning c
alorimetry showed the presence of amylose-lipid complexes in all rice sampl
es and of retrograded amylopectin in PP. Amylose retrogradation was not det
ected in any of the rice samples.
Conclusions: All rice test meals were low-glycaemic in type 2 diabetic subj
ects. There was no effect of TP on glycaemic index, whereas PP reduced the
glycaemic index by almost 30% compared to NP.