Effect of frying and storage on oxidative quality of conjugated linoleic-acid-rich soybean oil produced by photoisomerization using plantain as a model system

BACKGROUND

Conjugated linoleic acid (CLA) is known to have beneficial properties to health. Naturally, in foods it is found in very low concentrations, and so these beneficial properties cannot be obtained. This study investigated the enrichment of soybean oil by photoisomerization, as well as assessing its oxidative stability during the frying process using plantain slices as a model system and after a storage period of 20 days at 60 °C.

RESULTS

The oxidative stability of soybean oil enriched with CLA by photoirradiation was measured based on the peroxide, p-anisidine, and Totox values, as well as by the polyphenol content, tocopherol content and DPPH^· scavenging capacity. The results obtained showed that a substantial amount of CLA was obtained by photoirradiation (31.73%). The oxidative stability values of the oil enriched with CLA showed good stability during a frying cycle; however, this stability decreased when it was stored and during the final frying cycles.

CONCLUSIONS

The results obtained indicated that photoirradiation is a good technique for obtaining oils enriched with CLA, and in this way CLA can be incorporated into foods; however, it is necessary to add antioxidants to improve their stability. © 2019 Society of Chemical Industry.

Physical, mechanical, functional and chemical properties of Mexican pink pinion (Pinus pinea L.)

The aim of the study was to evaluate the physical and mechanical properties of the nut and kernel of the Mexican pink pinion (Pinus pinea L.), as well as the physicochemical and functional properties of whole pink pinion meal (WPPM) as well defatted pink pinion meal (DPPM). The length, width, thickness, geometric diameter, arithmetic diameter, sphericity, aspect ratio, surface area, volume, density and hardness of the nut were higher than those of the kernels. The kernel had the highest coefficient of friction, while the nut had the highest angle of repose. WPPM had high fat and protein contents, at 40.5 g/100 g and 41.1 g/100 g, respectively. The major component of DPPM was protein (64.85 g/100 g). The DPPM had higher water absorption, oil absorption, emulsifying and lower gelation capacities (4%), indicating that the meal is a potential source of protein isolates or additives for functional foods and WPPM in food formulations.

Effect of enzymatic pretreatment on the physical quality of plantain (Musa ssp., group AAB) employing airflow reversal drying

This work aimed to evaluate the effect of enzymatic pretreatment on the color and texture of plantain (Musa ssp., group AAB) dried by airflow reversal drying. Plantain slices 1.0 cm thick were used. Pretreatment with two commercial enzymes, Pectinex Ultra SPL (Aspergillus aculeatus) and Pectinex 3XL (Aspergillus niger), was performed. Drying kinetics were determined with and without pretreatment at temperatures of 50, 65 and 80 °C using a fixed bed convective dryer. An air speed of 6 m/s, a bed height of 5 cm and either unidirectional flow or airflow reversal (every 15 min) were used for drying. Color and texture were analyzed, and consumer acceptance of the results of the best treatments was determined. Pretreatment with the enzyme A. niger and airflow reversal gave the best drying kinetics and showed the greatest reduction in drying time (59.0%) at 80 °C. The best hardness results were found at 80 °C with A. niger enzymatic pretreatment with both types of air flow. Brightness and hue angle showed that samples pretreated with enzymes and dried at 65 °C had a lighter yellow color compared to non-pretreated samples. Plantain samples enzymatically pretreated and dried at 65 and 80 °C were the most accepted by consumers. This kind of enzymatic pretreatment on plantain could allow the conservation of some physical properties and reduction of drying times relative to the current methodology.

Caracterización de la leche y clasificación de calidad mediante análisis Cluster en sistemas de doble propósito

Debido a la falta de información sobre la calidad de la leche y la heterogeneidad en los sistemas de doble propósito del trópico mexicano, la capacitación no se destina a los grupos que la requieren. Por lo tanto el objetivo de este estudio fue caracterizar la leche de estos sistemas, compararla con las normas de referencia y relacionarla con las prácticas de manejo. Además de proponer una metodología para identificar los grupos que requieren acciones de intervención. Se evaluó la composición fisicoquímica y microbiológica en 192 muestras de leche cruda en siete localidades. Se determinó el efecto de las prácticas de manejo sobre las características de la leche mediante análisis de varianza. Se aplicó un análisis cluster para agrupar las muestras con base en el contenido de grasa, sólidos no grasos, crioscopía y acidez titulable. El 65 % de las muestras presentaron valores fuera de norma (sólidos, densidad y crioscopía, sugiriendo una adulteración por adición de agua). El uso de oxitocina, tipo de ordeño, raza y suplementación afectaron (P<0.05) las características de la leche. Mediante el análisis cluster se identificaron cinco grupos de calidad. Los grupos de excelente y buena calidad presentaron valores dentro de las normas de referencia en todos los parámetros evaluados. Los grupos de deficiente, mala y muy mala calidad (47 %) presentaron valores elevados de crioscopía y bajo contenido de sólidos. Con la metodología propuesta se espera facilitar la intervención enfocada a resolver problemas específicos, evitando el dispendio de recursos

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.

Physical properties of ebony seed (Pithecellobium flexicaule) and functional properties of whole and defatted ebony seed meal

A partial characterization was done of ebony (Pithecellobium flexicaule) seed physical properties, and how defatting affected some functional properties of ebony seed meal. Average seed dimensions were 13.02 mm length, 8.78 mm width and 9.65 mm thickness. Geometric diameter was 10.76 mm, volume was 530 mm(3), surface area was 364.33 mm(2), sphericity was 83.26 % and aspect ratio was 68.24 %. Thousand-seed weight was 0.70 Kg, of which 0.42 Kg (60 %) represented the kernel. Defatted ebony seed meal differed from whole meal in all measured parameters, particularly in its protein (44.72 g/100 g) and carbohydrates (44.12 g/100 g) proportions. The defatted meal had higher water absorption capacity (1.28 g/g sample), water solubility capacity (26.06 %), oil absorption capacity (2.04 g/g sample), emulsifying capacity (53.78 %) and gelling capacity (8 % w/v) than the whole meal. Ebony seed physical properties may prove useful in designing post-harvest processing equipment and in quality control. The high protein content of defatted ebony seed meal suggests its use as a natural alternative ingredient in numerous food industry applications.

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

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.