Cecilia E. Martínez-Sánchez

Influence of extrusion on the bioactive compounds and the antioxidant capacity of the bean/corn mixtures

The aim of this investigation was to examine the influence of extrusion on the bioactive compounds and the antioxidant capacity of bean/corn mixtures. Whole bean flour and nixtamalized corn were mixed in a 60:40 proportion and extrusion was performed in different moisture (14.5%, 15.4%, 17.1% and 18.0%) and temperature (150°C, 160°C, 170°C, 180°C and 190°C) conditions in order to find the optimal extrusion conditions. According to their functional properties and antioxidant status, the mixtures 142°C/16.3% H, 170°C/16.3% H and 198°C/16.3% H were defined as optimal, moderate and bad, respectively. Total polyphenols and flavonoids in the mixture of 142°C/16.3% H (15.09±1.7 mg gallic acid equivalent [GAE]/g dry weight [DW] and 1.57±0.2 mg catechin equivalent [CE]/g DW) were significantly higher (P<0.05) than in the sample 170°C/16.3% H (9.42±1.1 mg GAE/g DW and 1.4±0.1 mg CE/g DW) and the mixture 198°C/16.3% H (6.46±0.8 mg GAE/g DW and 0.78±0.1 mg CE/g DW). The antioxidant activity (37.02±3.8 and 25.01±2.5 µM Trolox equivalent [TE]/g DW) of mixture 142°C/16.3% H, determined by the cupric reducing antioxidant capacity with Trolox equivalent antioxidant capacity and β-carotene–linoleic acid (β-carotene,% of inhibition) assays, was significantly higher (P<0.05) than in 170°C/16.3% H (25.69±2.8 and 17.02±1.8 µM TE/g DW) and in mixture 198°C/16.3% H (13.93±1.5 and 8.94±0.9 µM TE/g DW), respectively. The free polyphenols, flavonoids and the antioxidant activities showed lower results than the hydrolyzed ones. The correlation coefficients between polyphenols, flavonoids, and cupric reducing antioxidant capacity capacities were between 0.93 and 0.99. In cereal proteins extracted and separated by electrophoresis, some differences were found in the sodium dodecyl sulfate–protein bands in the region from 36 to 45 kDa for 142°C/16.3% H, in comparison with other samples. Therefore, there is a need to find such conditions for the extrusion procedures that would take into consideration the contents of the bioactive compounds and the antioxidant capacity in the end product.

Effect of Osmotic Dehydration on Air-Drying Characteristics of Chayote

In this study the effect of osmotic dehydration (OD) on the air-drying kinetics of chayote (Sechium edule (Jacq.) Swartz) fruits was investigated. Fresh and osmotically dehydrated chayote parallelepipeds (1 × 1 × 2 and 4 × 4 × 2 cm) were subjected to convective drying at air temperatures of 50 and 60°C, with air velocities of 1.5 and 2.5 m/s. The OD pretreatments were performed in 10 and 25% NaCl solutions (w/w) at 25°C during 3 h using a solution-to-fruit mass ratio of 4:1. The use of higher air velocities notably accelerated drying rates as manifested through significantly higher drying rate constants estimated with Pages model, whereas no effect of temperature was observed. A previously reported analytical solution that considers both product shrinkage and variable diffusivity was generalized to describe the drying kinetics of food products with parallelepiped geometry. Selected drying experiments were then fitted to this solution using six different sets of model assumptions. Results indicated that product shrinkage is the main factor to be considered in order to estimate reliable values for diffusion coefficients. The OD pretreatments produced a significant reduction of the initial moisture content of chayote slabs before drying, thus allowing shorter drying time, which may lead to reduced energy consumption.

Effect of oil extraction assisted by ultrasound on the physicochemical properties and fatty acid profile of pumpkin seed oil (Cucurbita pepo).

The effects of amplitude and time of ultrasound-assisted extraction on the physicochemical properties and the fatty acid profile of pumpkin seed oil (Cucurbita pepo) were evaluated. Ultrasound time (5-30 min) and the response variables amplitude (25-100%), extraction yield, efficiency, oxidative stability in terms of the free fatty acids (FFA) of the plant design comprising two independent experiments variables, peroxide (PV), p-anisidine (AV), totox value (TV) and the fatty acid profile were evaluated. The results were analyzed by multiple linear regression. The time and amplitude showed significant differences (P<0.05) for all variables. The highest yield of extraction was achieved at 5 min and amplitude of 62.5% (62%). However, the optimal ultrasound-assisted extraction conditions were as follows: ultrasound time of 26.34 min and amplitude of 89.02%. All extracts showed low FFA (2.75-4.93% oleic acid), PV (1.67-4.68 meq/kg), AV (1.94-3.69) and TV (6.25-12.55) values. The main fatty acids in all the extracts were oleic and linoleic acid. Therefore, ultrasound-assisted oil extraction had increased performance and reduced extraction time without affecting the oil quality.

Preparation of betulinic acid nanoemulsions stabilized by ω-3 enriched phosphatidylcholine

Bioactive compounds such as ω-3 fatty acids and terpenes, have been associated with beneficial health effects; however, their solubility in the gastrointestinal tract and its bioavailability in the body are low. Nanoemulsions offer a viable alternative to disperse lipophilic compounds and improve their dissolution, permeation, absorption and bioavailability. Enzyme modified phosphatidylcholine (PC) with ω-3 fatty acids was used as emulsifier to stabilize oil-in-water nanoemulsions generated using ultrasound device. These systems were used as carriers of betulinic acid, which has reported anti-carcinogenic activity. Phospholipase-catalyzed modification of PC allowed the incorporation of 50 mol% of ω-3 fatty acids. Formation variables such as oil type and ultrasound amplitude had effects on nanoemulsion characteristics. Incorporation of betulinic acid affected globule size; however, betulinic acid nanoemulsions below 200 nm could be prepared. The conditions under which betulinic acid nanoemulsions were obtained using the modified phosphatidylcholine with the smaller globule size (91 nm) were 10% PC, 25% glycerol, medium chain oil and 30% amplitude for 12 min in the sonicator. Storage temperature had an effect on the stability of the nanoemulsions, at 5°C we observed the smallest growth in globule size. The use of olive oil decreased the globule size growth during storage of the nanoemulsion stabilized with modified phosphatidylcholine, although globule size obtained was greater than 200 nm. Medium pH had a significant effect on the nanoemulsions; alkaline pH values improved storage stability. These results provide useful information for using this type of carrier system on the formulation of products in the pharmaceutical or food industry.

Evaluation of physical and chemical properties of carrots dried by Refractance Window drying

ABSTRACT The Refractance Window™ (RW) technique was used to dry carrot slices (3 cm diameter; 0.2 and 0.4 cm thickness) at 74 and 94°C. Moisture loss, texture, color, total polyphenol content (TPC), and antioxidant activity (AA) were evaluated as response variables and were compared with the values of a control (fresh carrot) and the slices dried via convective drying (C) at the same temperatures. The RW method produced a reduction of drying time of 26–51% (p < 0.05) when compared to convective drying. The color, TPC, and AA values for the RW treatment did not differ (p > 0.05) compared with the control. The texture values showed a difference with respect to the control for the two drying methods used. However, between the two drying methods there was no difference in the texture (p > 0.05). The results suggest that the RW technology can be used to develop products with better functional properties compared with those obtained via conventional air-drying methods.

Producción enzimática de maltodextrinas a partir de almidón de malanga (Colocasia esculenta) Enzymatic production of maltodextrins from taro (Colocasia esculenta) starch

Starch was isolated from taro (Colocasia esculenta) tubers and partially characterized in order to be used as starting material to obtain maltodextrins by enzymatic hydrolysis. The starch was extracted with a yield of 858 g/kg and it had 269.2 and 554.8 g/kg of amilose and amilopectin contents, respectively. Maltodextrins with dextrose equivalent (DE) of 15.12 and 17.48% were obtained at 95 °C during 48.6 and 79.4 min, respectively. Moisture content of taro maltodextrins (TM) was similar to commercial corn (CCM) maltodextrins for each DE (15 or 17.5%), whereas the ash content of TM was higher than CCM with DE 15%. Fat content was higher (p < 0.05) in TM than CCM with DE 15 or 17.5%. There was no difference (p > 0.05) in pH between TM and CCM with the same DE. However, aw of TM was significantly lower than CCM. Average degree of polymerization (DP) was lower in TM than CCM with DE 15%. Average molecular weight (MW) of TM was lower than CM. Color was significantly different between both maltodextrins, except in L value of 15% DE maltodextrins. The analysis of functional properties suggests that CM could be replaced by TM in food systems which require water and oil absorption properties and in food emulsions.

Impact of micronized starfruit (Averrhoa carambola L.) fiber concentrate on lipid metabolism in mice

Abstract The objective of this study was to evaluate the effect of micronized insoluble fiber from starfruit bagasse as an ingredient of a functional food (FF) or as micronized insoluble fiber-rich fraction (IFRF) and its effects in vivo on lipids metabolism in a murine model. Experimental animals were divided in four isoproteic (15.8%) treatments differing on the fiber and cholesterol level used. The micronized IFRF particle size ranged from 37.5 to 149 μm. Treatments with added IFRF and those including the FF lowered serum triacylglycerols, total cholesterol (TC), high-density lipoproteins (HDL), and low-density lipoproteins (LDL) concentrations (IFRF: 14.2, 25.4, 55.06, and 12.18%, respectively; FF: 30.18, 39.47, 35.11, and 43.18%, respectively). IFRF produced the overall highest serum hypolipidemic effect and prevented the development of non-alcoholic fatty liver. Both the IFRF and the FF exhibited hypolipidemic effects that suggest a potential role of starfruit insoluble fiber as a component of FFs aimed against cardiovascular diseases.

Effect of some variables on oil extraction yield from Mexican pumpkin seeds

The effect of particle size (0.59 and 1.19 mm), meal to solvent ratio (1:5, 1:10, 1:15, and 1:20 w/v) and contact time (0, 1, 2, and 5 h) on oil extraction yield and efficiency from pumpkin (Cucurbita pepo) seeds using n-hexane were evaluated. Fatty acids profile was determined for the extracted oil. Results were analyzed by response surface methodology. Particle size, meal to solvent ratio and contact time, affected (p < 0.05) extraction yield. The yield (422 g/kg) and efficiency (860 g/kg) were highest at 0 h contact time, 0.59 mm particle size and a 1:20 (w/v) pumpkin seed meal:solvent ratio. Pumpkin seed oil contained (755 g/kg) unsaturated fatty acids and an elevated content of linoleic (431 g/kg) and oleic acids (324 g/kg). It is therefore classified as a high linoleic-oleic acids oil, making it a promising substitute for cotton, corn, sesame, sunflower, or soybean oils in our Mexican diet.

Conjugated linoleic acid content in selected Mexican beef and dairy products

The purpose of this study was to assess the conjugated linoleic acid (CLA) content of some commercial beef cuts and dairy products. Levels of CLA ranged between 3.75 and 20.45 mg/g fat, corresponding to 2% milk and cooked ground beef. On the basis of serving size, CLA content ranged between 12.87 and 93.62 mg/portion, corresponding to cream cheese (portion of 15 g) and cooked ground beef (portion of 100 g). There was no direct relationship between CLA content and the amount of fat provided per serving size in dairy foods. This study showed the presence of significant amounts of natural CLA in beef and dairy fats in the foods analyzed.

Preparation, composition, and functional properties of a protein isolate from a defatted mamey sapote (Pouteria sapota) seed meal

The proximate composition, functional properties, and proportion of protein fractions in a mamey sapote defatted meal (MSDM) were investigated. Additionally, a mamey sapote protein isolate (MSPI) was obtained by isoelectric precipitation from MSDM and partially characterized. MSDM had a protein content of 240.6 g/kg with the following protein distribution: glutelins (57.25%), prolamins (18.65%), albumins (17.85%) and globulins (6.25%). The maximum solubility and precipitation of MSDM proteins were found at pH 9.8 and 3.5, respectively. MSPI had a protein content of 950.9 g/kg and an in vitro digestibility of 73.6%. MSPI exhibited a lower water absorption capacity than MSDM but higher oil absorption and emulsifying capacities. The highest foam capacity (76.79%), foam (29.73%) and emulsifying (70.0%) stabilities of MSPI were obtained at pH 10. These results demonstrate that MSDM is a suitable material for the production of a high-purity protein isolate that could be used as an ingredient in meat or bakery products.