Isabel Goñi

A starch hydrolysis procedure to estimate glycemic index

Abstract An in vitro procedure to measure the rate of starch digestion in starchy common foodstuffs was developed. A first-order equation that rules the hydrolytic process was found: CC∞ (1−e −kt ). Besides an in vivo assay, to calculate the glycemic index (GI), was carried out on thirty healthy volunteers. This is a simple in vitro method that could be used to estimate the metabolic glycemic response to a food. The best correlated value with in vivo glycemic responses was the percentage of starch hydrolysis at 90 min (r= 0.909, p≤0.05, GI 1 = 39.21 + 0.803(H 90 )).

Analysis of resistant starch : a method for foods and food products

Abstract A method for resistant starch (RS) determination in food and food products is proposed. The main features are: removal of protein; removal of digestible starch; solubilization and enzymatic hydrolysis of RS; and quantification of RS as glucose released. Stomach and intestine physiological conditions (pH, transit time) were approximately simulated. All operations were performed in a 50ml centrifuge tube. Reference materials and food products were analysed by three laboratories. Statistical analysis included repeatability and reproducibility. This procedure is quite satisfactory for starchy foods containing appreciable quantities of RS and it may be useful for nutritional labelling of foodstuffs. For samples containing ⩽ 1% RS, differences are not significant and they can be considered as foods with a negligible RS content.

Effects of grape antioxidant dietary fiber in cardiovascular disease risk factors

OBJECTIVE The objective of the study was to evaluate the effects of a grape product rich in dietary fiber and natural antioxidants on cardiovascular disease risk factors. METHODS A randomized, controlled parallel-group trial was carried out. Thirty-four non-smoking (21 normocholesterolemic and 13 hypercholesterolemic) adults were supplemented for 16 wk with 7.5 g/d of grape antioxidant dietary fiber, a natural product containing 5.25 g of dietary fiber and 1400 mg of polyphenols. Nine non-supplemented non-smokers were followed as a control group. Fasting blood samples, blood pressure, and anthropometric readings were obtained at baseline and at week 16. Subjects were allowed to consume their regular diet, which was monitored weekly. RESULTS Grape antioxidant dietary fiber (7.5 g/d) reduced significantly (P < 0.05) total cholesterol (9%), low-density lipoprotein cholesterol (9%), and systolic and diastolic blood pressures (6% and 5% respectively). Greater reductions in total cholesterol (14.2%) and low-density lipoprotein cholesterol (11.6%, P < 0.05) were observed in hypercholesterolemic subjects. No changes were observed in the control group. There was a reduction of 2.5 points in the Framingham Global Risk Score in the supplemented group. A significant reduction in triacylglycerol concentration took place in the supplemented hypercholesterolemic subjects (18.6%, P < 0.05). CONCLUSION Grape antioxidant dietary fiber showed significant reducing effects in lipid profile and blood pressure. The effects appear to be higher than the ones caused by other dietary fibers, such as oat fiber or psyllium, probably due to the combined effect of dietary fiber and antioxidants.

Effect of Grape Pomace Concentrate and Vitamin E on Digestibility of Polyphenols and Antioxidant Activity in Chickens

Grape pomace provides a rich source of polyphenols that have the capacity to act as powerful antioxidants. An experiment was conducted to study the effect of inclusion of grape pomace concentrate (GPC) at levels of 15, 30, and 60 g/kg and alpha-tocopheryl acetate (200 mg/kg) in broiler chicks (21 to 42 d of age) on performance; digestive organ sizes; protein; fat; hydrolyzable polyphenol and condensed tannin digestibilities; the anti-oxidant activity of diet, serum, ileal content, and excreta; and the susceptibility to oxidation of breast meat during refrigerated storage. The inclusion of GPC did not affect the performance; the apparent ileal digestibility of CP; the relative abdominal fat, liver, pancreas, and spleen weight; and the relative intestinal length. Fat digestibility was reduced in birds fed control and GPC diets compared with birds fed vitamin E. Ileal and fecal digestibility of hydrolyzable polyphenols and condensed tannins reached values in a range of 56 to 73% and 14 to 47%, respectively. The GPC diets reduced ileal and fecal digestibility of hydrolyzable polyphenols. Antioxidant activity in GPC diet, ileal content, and excreta [2, 2-azinobis (3-ethilenzotiazolin)-6-sulfonate method] and GPC diet (ferric antioxidant power method) exhibited higher scavenging free radical capacity than control and vitamin E diets. The lipid oxidation in breast meat was lower in the birds fed the supplemented vitamin E diet than the control diet after 1, 4, and 7 d of refrigerated storage. Oxidative stability in breast meat at 1, 4, and 7 d of storage was equivalent in GPC diets compared with the vitamin E diet. In conclusion, the inclusion of GPC (up to 60 g/kg) did not impair chicken growth performance, digestive organ sizes, and protein digestibility. Hydrolyzable polyphenols were more bioavailable than condensed tannins. Antioxidant activity in diet, excreta, ileal content, and breast muscle were increased in GPC diets. The GPC supplementation was equally as effective in antioxidant potential as vitamin E. On the basis of these observations, we concluded that GPC could be a new source of antioxidant in animal nutrition.

Chickpea flour ingredient slows glycemic response to pasta in healthy volunteers

Abstract Diets with a low glycaemic index have been shown to improve glucose tolerance in both healthy and diabetic subjects. However, there is a need for a more diversified range of foods with a low glycaemic response. The object of this work was to make a spaghetti, containing chickpea flour, as a food having a low postprandial glycaemic response. Twelve healthy volunteers consumed three test meals containing 50 g of carbohydrates: white bread, wheat spaghetti and spaghetti, in which the wheat was partially substituted by chickpea flour. Blood samples were collected over 2 h after consumption of meals to evaluate the glycaemic response and to determine the glycaemic index. Nutritional composition and in vitro starch hydrolysis of pasta were determined. The incorporation of chickpea flour increased the mineral, fat and indigestible compound content of the pasta, but total starch content was not affected. Starch hydrolysis was lower in both types of pasta than in white bread, but the difference was greater in the case of pasta made with chickpea flour. The glycaemic indices (GI) of both types of pasta were in the normal range for lente carbohydrates but were significantly lower in the pasta containing chickpea flour (GI wheat spaghetti : 73±5; GI wheat–chickpea spaghetti : 58±6). The inclusion of chickpea flour, as an ingredient in pasta products, evidently provide a food with a low glycaemic response and could help in achieving a wider range of low-GI foods for the consumer.

Measurement of Health-Promoting Properties in Fruit Dietary Fibres: Antioxidant Capacity, Fermentability and Glucose Retardation Index

The aim of this work was to compare some in uitro health-promoting properties in fruit dietary fibre (antioxidant activity, fermentability and glucose retardation index), which could be useful to predict their physiological effects better than physico-chemical analyses. These properties were evaluated in mango and lemon peel fibre. Mango fibre was better than lemon fibre because of the highest values of antioxidant activity (67.6%) and glucose retardation index (21.5%). Antioxidant activity is proposed as a new health-promoting property associated to dietary fibre.

Definition of the Mediterranean Diet Based on Bioactive Compounds

Antioxidant (polyphenols and carotenoids) and nonantioxidant (phytosterols) bioactive compounds and dietary fiber may have a significant role in health. The intake of these compounds is strongly linked with the high consumption of fruits, vegetables, and unrefined cereals. A whole-diet approach to these food constituents is intended to render the current definition of Mediterranean diet based on food consumption more comprehensive. The Mediterranean dietary pattern can be characterized by the following four essential dietary indicators: 1) Monounsaturated to saturated fatty acid ratio (range: 1.6 to 2.0); 2) Intake of dietary fiber (41 to 62 g/person/day); 3) Antioxidant capacity of the whole diet (3500 to 5300 trolox equivalent/person/day); 4) Phytosterols intake (370 to 555 mg/person/day). The contribution of foods and beverages to these parameters is described. Spanish National Food Consumption Data for the years 2000 and 1964 were used to quantify the lowest and highest range values. The occurrence of these indicators in the Mediterranean diet has specific characteristics and there is sufficient scientific evidence to support the beneficial health effects.

Stimulatory role of grape pomace polyphenols on Lactobacillus acidophilus growth.

Grape pomace is a natural product rich in dietary fiber and polyphenols. A major part of dietary polyphenols is not absorbed in the small intestine and can interact with colonic microbiota. The influence of grape polyphenols on Lactobacillus acidophilus CECT 903 growth was investigated through agar diffusion assays and cultures in liquid media. Grape phenolic extracts and some standards of phenolic compounds (caffeic acid, gallic acid, tannic acid, catechin, epicatechin, and quercetin) were assayed. All phenolic compounds tested did not exert an inhibitory effect on L. acidophilus growth at a maximum concentration of 5000 microg/disk in agar diffusion assays. In addition, a stimulatory trend in bacterial growth was observed in both grape phenolic extracts and tannic acid. The major finding was that grape pomace phenolic extract (1mg/mL) induced a significant biomass increase of L. acidophilus grown in liquid culture media. Further research into the interaction between phenolic compounds and other intestinal bacteria, as well as healthy consequences, is required.

Klason lignin, condensed tannins and resistant protein as dietary fibre constituents : determination in grape pomaces

Abstract Dietary fibre (DF) determinations were carried out on grape pomaces by AOAC and spectrophotometric procedures. Insoluble dietary fibre (IDF) and Klason lignin (KL) residues contained appreciable amounts of condensed tannins (CT) and resistant protein (RP). The presence of CT and RP in the residues obtained after the successive action of amylase, protease and amyloglucosidase and chemical treatments with H2SO4 and HCl-triethyleneglycol, together with similar data previously reported for other samples could be considered in a wider definition of the DF complex as ‘indigestible polysaccharides, phenolic polymers and resistant protein’. The term ‘phenolic polymers’ includes both lignin and CT.

Bioactive Compounds of Four Hot Pepper Varieties (Capsicum annuum L.), Antioxidant Capacity, and Intestinal Bioaccessibility

Pepper fruits (Capsicum annuum) contain a wide array of phytochemicals with well-known antioxidant properties. Since bioactive compounds depend on their bioavailability to exert beneficial effects, it was crucial to estimate the extent of release from the food matrix and thus their bioaccessibility. Accordingly, we determined the individual carotenoid and phenolic content as well as the antioxidant properties of four red hot dried cultivars (Capsicum annuum L.) of high consumption in Mexico and estimated the extent of intestinal bioaccessibility of carotenoids with significance in human health, beta-carotene, beta-cryptoxanthin, and zeaxanthin, using an in vitro gastrointestinal model. Hot dried peppers at ripe stage had a high content of bioactive compounds that exhibited significant antioxidant properties (26-80 micromol trolox equivalents/g of dry matter), such as polyphenols (>2000 mg/100 g of dry matter) and carotenoids (95-437 mg/100 g of dry matter), which were partially bioaccessible. The amount released from the food matrix by the action of digestive enzymes was about 75% for total polyphenols, up to 49% for both beta-carotene and zeaxanthin, and up to 41% for beta-cryptoxanthin. The results suggest that from 50 to 80% of these carotenoids could reach the colon to be potentially fermented or could remain unavailable.