Carmen Sáenz

Opuntia spp mucilage's: a functional component with industrial perspectives

Opuntia genus is widely known for its mucilage production. Mucilage, a complex carbohydrate with a great capacity to absorb water, should be considered a potential source of industrial hydrocolloid. Mucilage contains varying proportions of l-arabinose, d-galactose, l-rhamnose, and d-xylose, as well as galacturonic acid. The mucilage content found in the cactus cladodes is influenced not only by the management of the crop but is also dependent on the temperature, irrigation and the rain. In some countries, small farmers use cactus mucilage to purify drinking water. Another traditional use is for improving house paint. Recently, a cactus cladode extract was tested to improve water infiltration in soils. Other properties of cactus mucilage, particularity culinary uses, have also been mentioned.

Cactus pear fruit: A new source for a natural sweetener

The use of cactus pear ( Opuntia ficus indica L.) to obtain a new natural liquid sweetener was studied. The juice of the fruit (16.5 ° Brix) was clarified with enzymes, treated with active carbon to take out the color and vacuum concentrated to obtain a 60 °Brix syrup or liquid sweetener. Physical and chemical characteristics determined included: aw; reducing sugars (as inverted sugar); glucose (%); ash content (%); sugar composition by TLC; OD (420 nm) and Y, x, y chromaticity coordinates; viscosity (cps) and density (g ml-1). Sensory analyses to determine the relative sweetness were also conducted. Cactus pear syrup contained 52.38% reducing sugar. The syrup had a pH of 4.31, a viscosity of 27.05 cps, an Aw of 0.83, a density of 1.2900 g ml-1, an acidity (as citric acid) of 0.74% and an ash content of 1.4%. Compared with traditional sweeteners such as fructose and glucose syrup, the acidity was greater than that of HFCS (high fructose corn syrup) of 0.035%, and the ash values were considered a little high compared to glucose syrup which is 1.0%; these disparities can be attributed to the different processing conditions employed. Sensory evaluation revealed the same relative sweetness for cactus pear syrup and glucose, but lower than fructose; cactus pear syrup had a relative sweetness value of 67 with respect to sucrose (100).

Influence of the Genotype on the Anthocyanin Composition, Antioxidant Capacity and color of Chilean Pomegranate (Punica granatum L.) Juices

The bioactive compounds content in pomegranate (Punica granatum L.) juice is variable and depends on agronomic factors, genetic and fruit maturity. In Chile, the areas with this crop have increased more than 65% in the last 5 years. This paper aims to determine the phenolic composition, antioxidant capacity and chromatic parameters of juices from eight Chilean pomegranate genotypes (PG2 to PG9), containing red (PG2 to PG6) or pink arils (PG7 to PG9). Color, total polyphenol content (using Folin-Ciocalteu reagent), total anthocyanins (by differences in absorbance at different pHs of the juice) and antioxidant capacity (oxygen-radical absorbance capacity, ORAC) were determined. Anthocyanins were identified and quantify using HPLC-DAD and HPLC/ESI-MS, the results were expressed as cyanidin-3-glucoside. ANOVA was used for establish differences between total polyphenols (TP), antioxidant capacity, total anthocyanins (TA), total polyphenols/total anthocyanins relations (TP/TA) and colour parameters. Statgraphics plus 7.0 was used. Genotypes PG2-PG6 (red arils) showing higher values for total polyphenols (10551280 mg L -1 ) and anthocyanins (588-1328 mg L -1 ) and higher ORAC values (21.2-24.4 μmol Trolox mL -1 ) than the pink arils PG7-PG9 (12.7-16.8 μmol Trolox mL -1 ) values. The latter genotypes showed the highest values of pH (3.5-3.7). The anthocyanin compounds identified in the juices were the 3-glucoside and 3,5-diglucoside derivatives of delphinidin, cyanidin and pelargonidin. Differences in their relative amounts were found among the Chilean pomegranate genotypes studied. The relationships between TP/TA and Pg/Cy (pelargonidin 3-glucoside and pelargonidine 3,5-diglucoside/cyanidin 3-glucoside and cyanidin 3,5-diglucoside) could be useful in the analytical characterization of Chilean pomegranate genotypes, as well as in the differentiation with other juices containing anthocyanins.

Microencapsulation of pulp and ultrafiltered cactus pear (Opuntia ficus-indica) extracts and betanin stability during storage.

Pulp (CP) and ultrafiltered (UF) cactus pear extracts were encapsulated with Capsul (C) by applying a central composite design (CP-C and UF-C systems) by spray-drying. To evaluate the effect of the extract, microparticles obtained under optimal conditions were characterised and stored at 60 °C. Betacyanin and betaxanthin encapsulation efficiency reached values above 98% for both systems studied. This efficiency was attributed to strong interactions between betalains and the polymer. Betalain degradation in CP-C and UF-C microparticles followed pseudo-first order kinetics. The betacyanin degradation rate constant was significantly higher for CP-C than for UF-C. These results suggested that the mucilage or higher sugar content of CP increased the hygroscopicity of the CP-C microparticles, leading to the degradation of betalain. The hydrolysis pathway was the main mechanism of betanin degradation during microparticle storage. These results demonstrate the potential utility of both CP-C and UF-C microparticles as natural colourants for healthy foods.

STRUCTURAL DETERMINATION AND CHEMICAL MODIFICATIONS OF THE POLYSACCHARIDE FROM SEEDS OF Prosopis chilensis Mol. (Stuntz)

The polysaccharide extracted from Prosopis chilensis seeds in acidic medium showed by total hydrolysis and gas-liquid chromatography analysis of the alditol acetates to be composed of galactose and mannose in the molar ratio 1.0:1.9. Studies by methylation and 1H and13C NMR spectroscopy indicated that the polysaccharide was a galactomannan with a chain of D-mannopyranosyl residues linked b 1 4 which carried alternatively a-D-galactopyranosyl residues at position O-6 of D-mannose units. The chemical modification of the galactomannan by reaction with sodium chloroacetate afforded in 95.3% yield, a derivative which gave a very viscous solution with water. By titration it was determined a carboxymethylation degree of 0.42 indicating that 64% of the alcoholic groups were etherified. Reaction of the galactomannan with TEMPO-NaCl-NaOBr system gave a water soluble polysaccharide. The DEPT 135o NMR spectrum indicated that the primary alcoholic groups of galactopyranosyl and unbranched mannopyranosyl residues were fully oxidised

Cactus pear cladodes powders as a source of dietary fibre: purification and properties

Cactus pear cladodes of 2–3 years were used to obtain a natural purified dietary fibre and their physical, chemical and technological properties were determined. The effect of particle size and washing temperature on the technological properties was studied. Purification produces a decrease in green colour (a*) and an increase in total dietary fibre but reduces the total phenolic compounds, mainly when cladodes are washed at higher temperatures. Technological properties did not present changes in the water retention capacity (WRC), water adsorption capacity and cationic exchange capacity, but it did in swelling capacity (SC), oil absorption capacity, apparent density and setting density, which were influenced by the particle size of the cactus powders. The purified fibre shows a high WRC between 5.20 and 5.86 g g− 1 and a high SC (7.02–8.27 mL g− 1). Purified fibre with a particle size between 600 and 1200 μm, independent of the washing temperature had better insoluble to soluble dietary fibre ratio, total phenolic content and technological properties.

Influencia de la época de cosecha sobre las características de la granadilla morada (Passiflora edulis Sims) y su jugo/Influence of harvest season on the characteristics of purple passion fruit (Passiflora edulis Sims) and its juice

The effect of two different harvest seasons (winter and summer) on some characteristics of passion fruit and juice was studied. Three different harvests were made during the two seasons every 15-20 days. The soluble solids/acid ratio was used as a ripeness index. The weight, diameter, peel thickness and yield of juice and seeds were determined in the fruit. Soluble solids, pH, acidity, total and reduced sugars, starch, pectin and pectinesterase activity were determined in the juice. A sensory evaluation of the quality and intensity of aroma was made. Influence of the date of harvest on the technological characteristics of the fruit and juice were observed. Winter fruits showed higher weight, diameter and peel thickness and lower juice yield than those from the summer harvest. The juice from the summer harvest showed a higher content of soluble solids, less acidity, and a higher content in starch, pectin and sugars than that of the summer harvest. The sensory evaluation showed that the aroma of the juice from the summer harvest was better in intensity and quality than that of the winter fruit.

Parámetros de color del jugo de granadilla (Passiflora edulis Sims): influencia de la época de cosecha de la fruta/ Color parameters of passion fruit juice (Passiflora edulis Sims): influence of harvest season

This study covers the evolution of color parameters (L*, a*, b*) of passion fruit juice from 2 different seasons (winter and summer) and its relation with carotenoid content and also the sensory evaluation of juices. Three different harvests were made during the two seasons, every 15-20 days. Soluble solids/acidity ratio was used as a maturity index. Winter maturity index was 3.5 and summer index was 6.6: The carotenoids content for winter fruit was higher than that for summer fruit (2.6 and 1.7 mg β-carotene/100ml respectively). Color differences between harvest seasons were observed; a* value for winter juices was higher than for summer juices (7.4 and 4.3 respectively). Furthermore, an increment of a* value was observed in the winter harvest rising from 5.0 to 10.3. A color difference was also detected through the sensory evaluation; the judges ranked the third harvest from winter with the highest degree. This sample had the highest carotenoid content (3.2 mg β-carotene/100 ml).

Clarification of purple cactus pear juice using microfiltration membranes to obtain a solution of betalain pigments

Betalains are fruit pigments possessing health-giving properties. To isolate the pigments, the juice must be separated from the fruit matrix, which contains biopolymers. The aim of this study was to clarify cactus pear juice by microfiltration to obtain a clarified juice containing betalains. For this purpose, two 0.2 µm pore size microfiltration membranes (ceramic and polymeric) were tested. The permeates were clear, free of turbidity and high in betalains (20%), also containing polyphenols and antioxidant activity, whereas the retained fractions were high in mucilage. The best separation was obtained using the ceramic membrane.

Red betalains from Opuntia spp.: Natural colorants with potential applications in foods

Natural red colorants are highly appreciated by the food industry, and betalains are one such category. There are few sources in nature of betalains, which are commonly obtained from red beet as a colorant additive and acceptable for addition to foods according the regulations of several countries. Red and purple Opuntia fruits could be a new source of these pigments for commercial purposes. The content of the pigment varies according the species and the extraction procedures. The stability of the pigments is another aspect to be considered. Betalains are also suggested as antioxidants and the final colorant could be considered as a functional additive. Additionally, the inhabitants of many arid zones of the world could benefit from an increase in the demand of Opuntia fruits, a plant with low growing requirements.