Angela Zuleta

Effect of Gamma Irradiation on the Functional and Nutritive Properties of Rice Flours from Different Cultivars

ABSTRACT The purpose of this work was to study the effect of minimal doses of γ-irradiation to reduce microbial loads (Co60, doses of 0, 1.5, and 3 kGy) on flour from three rice cultivars with different amylose contents (AC) grown in Argentina: RP2 (AC 25%), Yerua (Y) (AC 19%), and Higokumochi (H) (AC 5%). Studies on some starch characteristics such as digestibility (rate of starch hydrolysis in vitro), gel viscosity and syneresis, and scanning electron microscopy (SEM) were performed. Results showed that γ-irradiation affects rice functional and nutritive characteristics proportionally with the dosage used. With 3 kGy, original digestibility values increased 37.5, 60, and 76%; gel viscosity decreased 52, 77, and 90%; and syneresis increased 0, 193, and 546% on RP2, Y, and H, respectively. Amylopectin was the starch fraction most affected as shown by SEM. Although some of these changes in cultivar attributes might be considered negative for traditional food formulations, they could help in the design of n...

Carbohydrate composition of ripe pineapple (cv. perola) and the glycemic response in humans

Brazil is the third largest producer of pineapple (Ananas comosus) and the market for fresh pineapple is sustained by the Hawaii and Perola cultivars. In this work the Perola cultivar was divided into three main parts, shell, core and pulp, for characterization. Moisture in the pulp was higher (between 10 and 15%) than in the shell and core. The amount of protein was higher in the core (35%) than in the pulp and shell. Perola contained relatively low concentrations of total ascorbic acid in the edible parts, although higher levels of ascorbic acid in the shell. Citric acid corresponded to almost 60% of the total organic acids. The total soluble sugars [~7-12% (FW)] were predominantly sucrose, fructose and glucose. The core had almost twice as much total sugar (12%) than the pulp (6.8%). The amount of insoluble dietary fiber was around 1%, and the soluble fiber was less than 0.1%. The pulp showed the highest concentration of polyphenols (0.49%) and antioxidant activity (33 µmol.g-1) out of the parts. The consumption of the pineapple pulp or core produced a high glycemic index (~93%), but considering the glycemic load, this fruit can be considered as low dietary.

Lactic Acid Fermented Products as Vehicles for Probiotics

For thousands of years microbial cultures have been used to ferment foods and prepare different kind of products. Unstable primary foodstuffs such milk, meat and vegetables can be conserved for relatively long periods of time (Table 1), maintaining their nutritious and caloric value by the use of lactic acid fermentation. Several traditional soured milks such as kefir, koumis, leben and others were used as foods and often therapeutically, before the existence of the actual knowledge on probiotics. The origins of cultured dairy products can be traced in the Bible and the sacred books of Hinduism. Metchnikoff at the beginning of the XX century proposed the beneficial effects of the lactic acid bacteria (LAB) on health and longevity.

Polydextrose Enhances Calcium Absorption and Bone Retention in Ovariectomized Rats

Purpose. To evaluate the effect of polydextrose (PDX) on Ca bioavailability and prevention of loss of bone mass. Methods. Twenty-four two-month-old ovariectomized rats were fed three isocaloric diets only varied in fiber source and content up to 60 days (FOS group, a commercial mixture of short- and long-chain fructooligosaccharide, OVX group fed AIN 93 diet, and PDX group). A SHAM group was included as control. Apparent Ca absorption percentage (%ABS), changes in total skeleton bone mineral content (tsBMC) and bone mineral density (BMD) and femur BMD, % Bone Volume, Ca and organic femur content, caecal weight, and pH were evaluated. Results. %ABS and caecum weight of PDX and FOS were higher, and caecum pH was lower compared to OVX and SHAM. PDX reached a higher pH and lower caecum weight than FOS possibly because PDX is not completely fermented in the colon. Changes in tsBMC and femur BMD in FOS and PDX were significant lower than SHAM but significantly higher than OVX. % Bone Volume and femur % of Ca in PDX were significantly higher than OVX and FOS but lower than SHAM. Conclusions. PDX increased Ca absorption and prevented bone loss in OVX rats.

Colonic and systemic effects of extruded whole-grain sorghum consumption in growing Wistar rats

Colonic effects of extruded whole-grain sorghum diets were evaluated using a model of growing rats. In all, twenty-four male Wistar rats were fed control (C), extruded white sorghum (EWS) or red sorghum (ERS). Consumption of sorghum diets showed satiety properties, with reduction of caecal pH, and lower activity of β-glucosidase and β-glucuronidase enzymes. Decreased copper zinc superoxide dismutase and manganese superoxide dismutase and increased catalase and glutathione peroxidase levels were observed in colonic mucosa. The induction of antioxidant enzymes occurred through the activation of the nuclear factor erythroid 2-related factor 2 protein and its subsequent translocation into the nucleus. ERS was able to decrease the proliferation of proximal mucosa of colon, demonstrating a possible effect against colorectal tumourigenesis. EWS increased proliferation and also apoptosis, ensuring the re-establishment of homoeostasis of the colonic mucosa. No antioxidant systemic effect (serum or hepatic level) was observed. It is likely that despite the extrusion the low bioavailability of the phenolic compounds of sorghum diets caused them to exert mainly acute effects at the colon level. Extruded whole-grain sorghum is a good functional ingredient that might be promising in dietary prevention of intestinal diseases.

Diseño de panes funcionales a base de harinas no tradicionales

Functional breads constitute an interesting alternative as a vehicle of new dietary fiber sources. Two ingredients which are obtained and used at regional levels were studied: green banana flour (GBF) (Musa acuminata var nanica) and American carob flour (CF) (Prosopis alba). Breads were made mixing these flours with wheat flour (WF): GBF/WF 50:50 and CF/WF 25:75. Proximal composition of all samples was assessed according to AOAC methods. Iron, zinc and calcium contents were determined by AAS and mineral dialyzability using an in vitro method. The studied flours as well as the breads were characterized by high dietary fiber contents (12.4 and 31.0 in GBF and CF; and 6.9 and 10.2 in the green banana and carob breads, respectively). Breads had about 22% less available carbohydrates than white bread. Mineral dialyzability increased in breads about 30 to 50%, since fermentation promotes phytates degradation. The greatest effect was observed on iron dialyzability. These results indicate that these flours might be promising ingredients for use in the design of functional breads, with important levels of dietary fiber. These breads may be labeled as high fiber products according to current national regulations (minimum 6%). The inclusion of CF contributed to higher iron and calcium levels while the use of GBF, due to its functional properties, allowed for a greater replacement of wheat flour.

α-Galactosides present in lupin flour affect several metabolic parameters in Wistar rats

The aim of this study is to evaluate the influence of α-galactosides present in a lupin diet on metabolic parameters in growing Wistar rats. Lupin (Lupinus albus) is a rich source of non-digestible carbohydrates called α-galactosides whose beneficial health effects have been widely reported. For our investigation, twenty male Wistar rats were fed with two different diets: control (C) and lupin flour (L) for a 60-day period. The fermentation of these α-galactosides was monitored by measuring the following indicators: changes in the dynamic lactobacilli and enterobacteriaceae population, cecal content pH, generation of short chain fatty acids (SCFA), Ca and P absorption, and serum lipid (triglycerides and cholesterol) contents. The body weight was lower in the L diet than that in the control with significant differences (p < 0.05). The microbial analyses showed an increase of total lactobacilli counts and a decrease of enterobacteriaceae counts in the L diet when compared to the control, with significant differences (p < 0.05). The fermentations of α-galactosides were also confirmed by decrease in pH levels and the formation of relevant SCFA in the cecal content. The total content of SCFA (μmol per g) at the end of the assay period reached values of 13.58 and 3.64 for L and C rats, respectively. This significant increase of total SCFA in the L diet is responsible for a low pH of the cecal content that in turn prevents the growth and development of potentially pathogenic bacteria (p < 0.05). Regarding lipids, serum triglycerides and cholesterol levels were significantly reduced in the case of animals fed with lupin flour with respect to C animals (p < 0.05). Finally, the L rats showed higher values of an apparent Ca absorption percentage and bone volume percentage with respect to the C animals (p < 0.05). All these results confirm that lupin flour which contains α-galactosides could possibly be considered as a functional ingredient with health promoting properties.