A rapid enzymic method for starch analysis, especially in cereal products, is presented. One person can analyze 30 samples per day. The method includes a 15 min gelatinization step in a boiling water bath in the presence of a thermostable α‐amylase, a 30 min amyloglucosidase incubation of a subsample, and subsequent determination of glucose with a glucose oxidase/peroxidase reagent. The method was evaluated by analysis of the starch content in various raw and industrially processed wheat samples. The method showed high precision (CV=0.6–1.0%) and accuracy. Some factors which might affect the enzymic availability of starch and thus its recovery in the analysis are evaluated and discussed.

Glycemic response after ingestion of starchy foods varies. Starch in many common ready-to-eat foods is only partly gelatinized. In view of this, the relationships among degree of starch gelatinization, in vitro digestion rate, and in vivo metabolic response in rats were studied. Wheat starch with different degrees of gelatinization was used in the experiments. Plasma glucose and insulin responses as well as the rate of in vitro hydrolysis with alpha-amylase were strongly correlated to the degree of starch gelatinization (r = 0.88, r = 0.90, and r = 0.96, respectively). Plasma glucose and insulin responses were also positively correlated to the rate of hydrolysis with alpha-amylase in vitro (r = 0.98 and r = 0.76, respectively). These results suggest that the degree of starch gelatinization is an important determinant both for the rate of starch hydrolysis in vitro and for the metabolic response in vivo.

Amylose from potatoes was complexed with lysolecithin and oleic acid. The degradation of complexed amylose by hog pancreatic α‐amylase in‐vitro was studied, as well as the in‐vivo absorption in the rat. The presence of a bacterial thermostable α‐amylase in the gelatinization step increased the result of a starch analysis using glucoamylase. Complexed amylose displayed a substantially reduced susceptibility to α‐amylase in‐vitro. However, when adding a large excess of enzyme, the complex was completely hydrolyzed after 3 h. Amylose‐lysolecithin complex disappeared from the gastrointestinal tract within 120 min. The complexed amylose was hydrolyzed and adsorbed to the same extent as free amylose in‐vivo but somewhat slower.

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Glucose and insulin responses to bread products were evaluated in healthy subjects. Also studied were the rate of in vitro starch digestion and the content of in vitro resistant starch (RS). Three white-wheat-bread (WWB) products varying in crust-crumb ratio and monoglyceride addition, three bread products with a high soluble fiber content (HSFB), and two coarse-wheat breads (CB) were included. The metabolic responses to WWBs were in general higher than those to CB and HSFB products. The most prominent reduction in metabolic responses was noted with the CBs with intact kernels and the HSFBs with oat bran. The starch in these products was also more slowly released from a dialysis tubing after enzyme incubation of chewed samples. The RS content ranged from 0 to 1.7 g/100 g starch. HSFBs and the CB with intact kernels showed a higher satiety score than did the WWBs immediately after the test meal.

Type 2 diabetes is associated with a higher cardiovascular risk and there has been a growing interest in using dietary intervention to improve lipid profile and glucose control. The present work aims at analysing the effects of the enrichment of a normal diet with b-glucan (3·5 g/d) in free-living type 2 diabetic subjects for 2 months, using a palatable soup. This trial was a parallel, placebo-controlled, double-blinded randomised study performed in fifty-three type 2 diabetic subjects. During a 3-week run-in period, subjects daily consumed a ready meal control soup (without b-glucan). For the following 8 weeks, subjects were randomly assigned to consume daily either a control soup or a b-glucan soup. Changes in lipid profile (total cholesterol (TC), HDL-and LDL-cholesterol (HDLc and LDLc), apo B and TAG) and in glucose control (HbA1c and fasting glucose) were measured. There was no significant alteration in lipid profile in the two groups (TC, HDLc, LDLc and apo B). TAG decreased significantly in the b-glucan group compared with the control group (2 0·12 (SD 0·38) v. 0·12 (SD 0·44) mmol/l, P¼ 0·03). HbA1c and fasting glucose were not reduced in any group. A single daily ingestion of 3·5 g b-glucan, as required by official dietary recommendations, for 8 weeks did not change the lipid profile and HbA1c in type 2 diabetic subjects. To improve the metabolic profile of type 2 diabetic subjects in the long term, the quantity, the food vectors and the tolerability of b-glucan products may be re-evaluated.

Properties of fresh potatoes, including dry matter (DM) content, starch content, and near-infrared (NIR) spectra, were determined and related to the sensory-perceived texture of the steam-cooked samples. To quantify these relationships, three potato cultivars, respectively representing a firm cooking potato (cv. Nicola), a mealy cooking potato (cv. Irene), and a cultivar (cv. Bintje) with intermediate cooking properties, were classified on the basis of three size categories. For each size category and cultivar a DM distribution was determined on the basis of the underwater weight of the individual potatoes. Each DM distribution was divided into three subcategories based on low, medium, and high DM contents. This categorization was performed for freshly harvested potatoes and for potatoes stored for 3 and 6 months, respectively. In total, this resulted in 27 DM distributions, of which 16 were non-normally distributed, and 81 samples. Linear relationships were established between the DM content, as determined by either underwater weight analysis or oven-drying, and the starch content. On the basis of partial least-squares regression (PLSR), statistical models were developed relating sensory-based texture descriptors with the DM matter content of the samples. It was also shown, by applying PLSR, that the NIR spectra, originating from the potato samples, could be related to the DM content and to the sensory-perceived texture. From the relationships between DM content and sensory-perceived texture, on the one hand, and from the DM content and NIR spectra, on the other, it was concluded that the DM content rather than the cultivar determines the sensory-perceived texture of steam-cooked potatoes. Cultivar-specific elements may also contribute to the perceived texture but are overruled by the DM content. Storage did not affect the mutual relationships between the DM content, the sensory properties, and the NIR spectra.

A differential scanning calorimetry (DSC) method for the determination of amylose as its amylose-L-a-lysophosphatidylcholine (LPC) complex is described. Potato amylose/amylopectin mixtures covering the range of 0-95% amylose were heated in the presence of LPC, cooled and then reheated to follow melting of the amylose-LPC complexes formed during the cooling phase. A linear relationship (r = 0.98) was obtained between the amylose content of the mixtures and the enthalpies of the amylose-lipid complexes. This linear calibration was used to predict the amylose content of various native starches, rice flours, wheat flour, durum wheat semolina, and lyophilized raw potato on the basis of the melting enthalpy of their amylose-LPC complexes. Except for the potato samples, amylose contents determined by the DSC method were in good agreement with those obtained from a colorimetric assay. Bestimmung vonAmylose durch Differential-Raster-Kalorimetrie. Eine Differential-Raster-Kalorimetrie(DSC)-Methode zur Bestimmung von Amylose in Form ihres Amylose-L-a-Lysophosphatidylcholin(LPC)-Komplexes wird beschrieben. Kartoffelamylosel-amylopektin-Mischungen mit Amylosegehalten von 0-95% wurden in Gegenwart von LPC erhitzt, abgekiihlt und wieder erhitzt. urn die wah-rend der Abkiihlphase gebildeten Amylose-LPC-Komplexe durch Schmelzen zu verfolgen. Es wurde eine lineare Beziehung (r = 0.98) zwischen dem Amylosegehalt der Gemische und den Enthalpien der Amylose-Lipidkomplexe erhalten. Diese lineare Eichung wurde genutzt, um den Amylose-Gehalt verschiedener nativer Starken, Reismehle, Weizenmehle, DurumweizengrieS und lyophilisierter Rohkartoffel auf der Basis der Schmelzenthalpie ihrer Amylose-LPC-Komplexe vorauszusagen. AuSer bei den Kartoffelproben waren die durch die DSC-Methode bestimmten Amylosegehalte in guter Ubereinstimmung mit den Ergebnissen mit denen einer kolorimetrischen Analyse. starchlstarke 45 (1993) Nr. 4, S. 136-139 0 VCH Verlagsgesellschaft mbH, D-6940 Weinheim, 1993 0038-9056/93/0404-0136$05.00+.25/0The starch swelling power tests have been reported to be a promising method for predicting the eating quality of Japanese white salted noodles. The relationships between starch swelling power and noodle eating quality were examined for a range of commercial Australian starchktarke 45 (1993) Nr. 4. S. 139-144