Bioavailability of starch in bread rich in amylose: metabolic responses in healthy subjects and starch structure.
OBJECTIVE
This study investigated whether postprandial metabolic responses to bread could be lowered by substituting high amylose maize starch for a part of the flour.


METHODS
Eight healthy subjects consumed test meals of equivalent nutritional composition based on white wheat bread, bread rich in amylose (HAWB) and spaghetti as a breakfast meal. Blood samples were collected to measure insulin and glucose concentration during two hours after consumption. The degree of starch crystallinity was investigated by X-ray diffraction and DSC analysis.


RESULTS
HAWB produced low glycaemic (60 +/- 18) and insulinaemic (57 +/- 20) indexes similar to those of spaghetti (83 +/- 46, 61 +/- 16). In vitro amylase hydrolysis of the three foods showed that high amylose content in HAWB significantly lowered starch degradation in bread without affecting hydrolysis kinetics. Addition of amylose in dough increased the resistant starch content of HAWB (14% of dry matter). The resistant starch fraction was mainly composed of crystalline amylose (B-type X-ray diffraction pattern, melting temperature 105 degrees C) attributable to native high amylose maize starch incompletely gelatinised during bread-cooking.


CONCLUSIONS
Bread produced by the substitution of high amylose maize starch for a part of wheat flour showed a low glycaemic index. Resistant starch in HAWB corresponded to native crystalline amylose not gelatinised during normal bread-processing conditions.
Hoebler
C
C
Centre de Recherche en Nutrition Humaine, CHU-Hôtel-Dieu, Nantes, France.
Karinthi
A
A
Chiron
H
H
Champ
M
M
Barry
J L
JL
D000328:Adult; D000688:Amylose / Q000032:analysis*; D001682:Biological Availability; D001786:Blood Glucose / Q000378:metabolism; D001939:Bread / Q000032:analysis*; D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D005260:Female; D005502:Food; D006801:Humans; D007328:Insulin / Q000097:blood; D007700:Kinetics; D008297:Male; D013213:Starch / Q000737:chemistry* / Q000493:pharmacokinetics*; D014961:X-Ray Diffraction
D001786:Blood Glucose; D007328:Insulin; D013213:Starch; D000688:Amylose