Peroxidase activity, chlorophylls and antioxidant profile of two leaf vegetables (Solanum nigrum L. and Amaranthus cruentus L.) under six pretreatment methods before cooking

Abstract

The study evaluated the effects of six pretreatment methods before cooking on the peroxidase activity, chlorophyll and antioxidant profile of Amaranthus cruentus L. and Solanum nigrum L. The six pretreatments methods used were chopped only (raw sample) (coded M1); chopped and dried at 50°C for 5 h (coded M2); chopped and squeezed in water (at room temperature) (coded M3); chopped and soaked in warm water (approximately 60°C), then cooled and squeezed (coded M4); chopped and soaked in salt-treated water (approximately 20 g NaCl per litre of water) for 15 min, then squeezed (coded M5) and chopped and soaked in boiling water (100°C), then cooled and squeezed (coded M6). The main effect of vegetable type and the main effect of pretreatment methods have significant effects (P 6 0.05) on the parameters measured, while the interaction of vegetable type and pretreatment methods have no significant effect on the parameters measured. Statistical analyses (P 6 0.05) showed that chlorophyll a and b occur in ratio 3:1 in the two vegetables, irrespective of the pretreatment imposed. Peroxidase activity test showed that A. cruentus, irrespective of the pretreatment imposed showed, no peroxidase activity, while S. nigrum showed high peroxidase activity for all the pretreatments except for M6. Results showed that there was a significantly (P 6 0.05) higher content of carotenoids in A. cruentus when compared with S. nigrum, while the total phenolics, total flavonoids and total tannins contents were higher in S. nigrum when compared with A. cruentus, irrespective of the pretreatment method used. For the two vegetables, the percentage losses in total carotenoids, phenolics, flavonoids and total tannins at M6 when compared with M1 were 53.3-60.5%, 55.6-57.1%, 62.4-63.6% and 66.1-73.5%, respectively. There was a sharp drop in the carotenoids, phenolics, flavonoids and tannins contents of the two vegetables at M4 and M6, with both treatments having closely similar values for each parameter.

<i>In vitro</i> anti-radical activities of extracts of <i>Solanum nigrum</i> (L.) from South Africa

“…Overall, the reducing power of all extracts increased along concentration gradient. The dosedependent antioxidant activity is in line with the findings of previous authors (Adebooye et al, 2008). The antioxidant activity of plants has been reported by previous authors to be connected with the development of reducing power (Sultana et al, 2009;Xia et al, 2011), the standard antioxidant agents could react directly with peroxides or prevent peroxide formation by reacting with certain precursors (Pattanayak & Sunita, 2008).…”

Caracterización de suelos cultivados con amaranto y algunos aspectos agronómicos de la planta

“…La cantidad de clorofila constituye uno de los indicadores de la capacidad fotosintética de las plantas, ya que representa una medida de las dimensiones del sistema fotosintético y de su eficiencia, lo que determina la producción de biomasa de la planta en diferentes condiciones de explotación. Adebooye et al (2008) mencionan que la clorofila se asocia de forma positiva con la tasa de fotosíntesis y por lo tanto, aumenta la producción de biomasa y rendimiento de la semilla. Malathy et al (2012) señalan que la conformación genética de la planta de amaranto y los factores ambientales influyen de forma significativa en la producción de pigmentos y en el crecimiento.…”

“…Nagamatsu et al (2004) reportaron una concentración de clorofila a de 69 a 143 mg g -1 en hojas de amaranto, valores inferiores a los encontrados en este estudio. De la misma manera, en plantas de Amaranthus cruentus, Adebooye et al (2008) obtuvieron una concentración de clorofila a de 1.32 mg g -1 , mientras que de clorofila b fue de 4.37 mg g -1 en hojas, valores menores que dependen de la disponibilidad de nutrimentos. Sánchez et al (2007) y Nakashima et al (2011 reportaron que los niveles de N y K correlacionan en una dirección positiva con la concentración de clorofila, lo que depende de la especie de la planta, los factores ambientales y condiciones nutrimentales.…”

“…Sitio 1 0.9 ± 0.01 a 1.0 ± 0.6 a 1.0 ± 0.8 a P (%) 0.2 ± 0.01 a 1.0 ± 0.7 a 1.0 ± 0.8 a K (%) 2.0 ± 0.03 a 1.0 ± 0.7 a 1.1 ± 0.8 a Adebooye et al (2008) we obtained chlorophyll concentration of 1.32 mg g -1 , while chlorophyll b was 4.37 mg g -1 leaves, lower values depending on the availability of nutrients. Sánchez et al (2007) and Nakashima et al (2011) reported that the levels of N and K are correlated in a positive direction with chlorophyll concentration, which depends on the plant species, environmental factors and nutritional conditions.…”

“…The amount of chlorophyll is an indicator of the ability photosynthetic plants, as a measure the dimensions of the photosynthetic apparatus and of its efficiency which determine biomass production of the plant in different operating conditions. Adebooye et al (2008) mention that the chlorophyll is positively associated with the rate of photosynthesis and thereby increases the production of biomass and seed yield. Malathy et al (20 January 2) show that the genetic y limo son poco permeables, son depósitos excelentes de agua y retienen nutrimentos que pueden ser utilizados por las plantas (Jaramillo, 2002).…”