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«International Journal of Agriculture and Crop Sciences. Available online at IJACS/2014/7-7/417-421 ISSN 2227-670X ©2014 IJACS Journal ...»

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International Journal of Agriculture and Crop Sciences.

Available online at www.ijagcs.com

IJACS/2014/7-7/417-421

ISSN 2227-670X ©2014 IJACS Journal

Investigation of Heavy Metals with some Methods on

vegetables

Armaghan Haghighitalab1*, Mostafa karami2,Ehsan Sadeghi3, Maryam Shahi4

*1. Department of Chemical engineering Food Sciences,Kermanshah Science and Research Branch,Islamic

Azad University,Kermanshah,Iran.

2. Faculty of Food Science and Technology, Buali-Sina University, Hamedan, Iran.

3. Research Center for Environmental Determinants of Health (RCEDH), Kermanshah University of Medical Sciences, Kermanshah, Iran.

4 M.Sc. in Microbiology,Tehran, Iran.

*Corresponding author email: armaghan_haghighitalab@yahoo.com ABSTRACT: Heavy metals ranks high amongst the chief contaminants of leafy vegetables and medicinal plants. Poisoning from heavy metal contamination of medicinal plant products has caused countless health implications including liver and kidney failure and even death. Several methods for determination of Se have been developed for many years. However, cooking may affect antioxidant content due to antioxidantrelease, destruction or creation of redox-active metabolites. Plants can amass trace elements, especially heavy metals, in and on their tissues due to their ability to tolerate potentially toxic ions in the environment. However, cooking may affect antioxidant content due to antioxidant release, destruction or creation of redox-active metabolites. However, this drying process is slow and metabolic processes may continue longer which may lead to quality loss of the plants and subsequently to the extracts, e.g. colour changes, loss in active ingredients. The effect of freezing on specific tissue within organs of other grass species has also been documented.

Key words: Cooking, Drying, Medicinal Plants, Pb, Zinc.

INTRODUCTION

Epidemiological and clinical studies have shown that the intakeof vegetables and fruit plays an important role in the protection ofhuman health, reducing the risk of several age-related diseasesincluding cardiovascular diseases, cancers. Heavy metals of non-anthropogenic origin are always present at a background level with their occurrence in soils being related to weathering of parent rocks and pedogenesis (Ghiyasi et al., 2010). However the concentration of several heavy metals has increased dramatically in certain ecosystems due to anthropogenic activities (Sarma et al., 2012). Heavy metals frequently occur as cations which strongly interact with the soilmatrix and can becomemobile as a result of changing environmental conditions (Qishlaqi andFarid Moore, 2007). Over 80% of the population in developing countries dependsdirectly on plants for their medical requirements.Traditional medicine is a key element among the rural communities in developing countries for the provision of primaryhealth care especially where there are inadequate primary healthcare systems (Shrestha and Dhillion, 2003).

Cd Cadmium (Cd) is a non-redox toxic heavy metal thatenters into environment from various anthropogenic sources aswell as upon rock mineralization (Nriagu and Pacyna, 1988). Cd pollution is a global environmental problem and nearly 30×103 tonnes of Cd enter the environment annually through various anthropogenic sources (Sanit`a di Toppi and Gabbrielli, 1999). Being largely immobile in nature, Cd persists and pollutes the soil. It is a non-essential metal for the plants and humans, enters crops through roots, accumulates in plants and affects human health (Metwally et al., 2005). In plants, Cd toxicity include reduction of plasma membrane H+–ATPase activity (Obata et al., 1996), inhibition of enzyme activities (Van Assche and Clijsters, 1990), disruption of plantwater status (Perfus-Barbeoch et al., 2002), inhibition of K+ uptake and reduction of cytokinin content (Veselov et al., 2003), alteration of nutrient levels (Sandalio et al., 2001), damage to light harvesting centre and PS II and negative effects on chlorophyll metabolism (Hsu and Kao, 2004), oxygen evolution rate, chlorophyll a Intl J Agri Crop Sci. Vol., 7 (7), 417-421, 2014 fluorescence and photo-synthesis (Baˇckor et al., 2007). In plants, Cd causes visible symptoms like reduction in root and shoots growth, chlorosis, leaf roll and necrosis, and even death, at higher concentrations. It is toxic even at very low concentrations and is a potential carcinogen (Vido, 2001). At cellular level, Cd induces oxidative stress as evidenced by enhanced lipid per oxidation, hydrogen peroxide (H2O2) generation and ion leakage (Sandalio et al., 2001;Wang et al., 2004; Rodr´ıguez-Serrano et al., 2006). It involves alterations in the level of antioxidant enzymes (Rodr´ıguez-Serrano et al., 2006) as a defense mechanism against Cd-induced reactive oxygen species (ROS) viz.H2O2, superoxide (O2 −) and hydroxyl radical (OH•).

Pb Lead (Pb) is a heavy metal known to pose significant risks to the health of humans,animals, and plants (Schell etal.,2010;Sharma andDubey,2005). Peyote mediation is an emerging technology based on green plants’abilityto bioaccumulation heavymetals from the environment (Pilon-Smits, 2005). Upon exposureto Pb,plants generally under go avoidance and tolerancemechan-isms (Verkleij and Schat, 1990) to reduc eth uptake of Pinto plants and copewiththeexcessPbthathasinevitablyenteredthecytosol.However,theresponseofplantstoPbdependsonplantspecie s, development al stage, Pb concentration, and theduration of exposure. In plants,Pbinducesoxidative stressbygenerationoflipidper oxidation and toxic reactive oxygenspecies (ROS), includingH2O2 (Malecka etal., 2001; Phangetal., 2010). Nitric oxide (NO)isinvolvedinplantresponses toabioticstresses,suchasheat, chilling,drought, salt UVirradiation,and ozone exposure,by acting as an antioxidant (Beligni andLamattina,1999,) Zn Zn is the second most abundant transition metal after iron (Fe) and is involved in various biological processes in organisms (Broadley et al., 2007). The effects of Zn on plants have been reviewed (Hacisalihoglu and Kochian, 2003; Rout and Das, 2003; Broadley et al., 2007), including the dominant fluxes of Zn in the soil–root– shoot continuum, Zn hyper accumulation, Zn deficiency and protective roles of Zn in plants. But the effects of Zn stress on nutrition uptake and antioxidant responses are not clearly elucidated.It has been reported that heavy metals, for example cadmium and lead (Sinha et al., 2006), can significantly affect the uptake and the translocation of some nutrients in plants.Excess Zn can also affect the uptake of other nutrient elements (Stoyanova and Doncheva, 2002).





There is now extensive interest in heavy metal transport by metal-tolerant plants (metallophytes) because of the repercussions for peyotemediation (Sarma, 2011). Heavy metal origin and content as well as their possible interaction with soil properties are priority objectives in environmental monitoring. This is due to the fact that apart from the source of heavy metals, the physicochemical properties of soil may alsoaffect the heavy metal concentration (Qishlaqi and Farid Moore, 2007).

DISCUSSION Many dietary agents are cooked, but, to date, the effects of cooking and comparison of cooking methods on antioxidant capacity of foods have not been well studied. In this study, we explored the effects of three cooking methods (boiling, steaming and microwaving) and two cooking times (5 and 10 min), performed under controlled laboratory conditions, on the total antioxidant capacity (as the FRAP value) and total phenolics content of four commonly consumed vegetables: broccoli, cabbage, cauliflower and choy-sum (a dark green Chinese cabbage).

These are all members of the genus Brassica which belong to the Cruciferous family and are reported to posses both antioxidant and health-promoting properties (Podsedek, 2007).

Commercial instant soups are available in the market in mostcountries. Freeze-dried instant vegetable soups are prepared withvarious vegetables as main raw materials, followed by seasoning,molding and freeze drying. The dried instant soup should retain thecolor, flavor and nutrition of the original vegetative. Adding somewater to the instant vegetative, it must recover the original state of thevegetative. However, high costs restricted the popularity of freeze-driedinstant vegetative.Freeze drying produces the highest-quality dried foods.

Buta major problem with conventional freeze drying (FD) is the longdrying time needed, which in turn leads to high energyconsumption and high capital costs (Liu et al.,2008). This is partly due to the poor heat transferrate associated with the conventional electric heating methodwhich transfers heat for drying by conduction. It is well known thatmicrowave radiation generates rapid volumetric heating of a wetmaterial by altering the electromagnetic field to interact primarilywith polar water molecules and ions in food materials (Varith et al., 2007).Toincrease the freeze drying rate, utilization of microwave heatinginstead of the traditional conduction heating has been proven togive better heat and mass transfer rate (Duan et al., 2008)

Intl J Agri Crop Sci. Vol., 7 (7), 417-421, 2014

It is probably because the addition of sucrose increasedthe dielectric permittivity of the vegetative.

However, it was found thatthe drying rate cannot be improved in the late drying stage. Thisis probably due to high viscosity of the material caused by highsucrose concentration in the final drying stage, or possibleformation of a peripheral layer of sucrose, which results in watertransfer being hindered. The drying rate reduction in the finaldrying stage due to sucrose infiltration was also observed bysome authors (Mandala et al., 2005) in some osmotic pretreatmentpreceding drying process.

METHODS Drying Dry vegetable are cultivated and consumed worldwide for their importance as a food crop nutritionally and economically. Cooking is the most prevalent method of preparation of dry vegetatives (Deshpande et al., 1984).A lot of effort has been made to study the hydration kinetics of dry beans and to investigate the change in moisture content, composition, and texture of beans as a function of soaking or cooking time and temperature (Candela et al., 1997).Drying is one of the most common methods that can be used to extend the shelf-life and to achieve the desired characteristics of a food product. Reducing the water activity (aw) of food via this process can minimize deterioration from chemical reactions and microbial activity. Drying, on the other hand, has an adverse effect on the quality of a dried product. Changes in color and texture normally occur during drying, for example. Therefore, a suitable scheme for drying food materials has to be determined to reduce various adverse changes. Moreover, blanching can help increase the drying rate, hence reducing the drying time (Severini et al., 2005; G َ◌rnicki and Kaleta, 2007).Drying is a process in which water is removed to halt or slow down the growth of spoilage microorganisms and the occurrence of chemical reactions. Dehydration plays an important role in extending the shelf life of fleshy agricultural products. In addition to preservation, drying is used to reduce the cost or difficulty of packaging, handling, storage, and transport by converting raw food into a dry solid. This action reduces the weight and sometimes the volume of a food (Barbosa-C‫ل‬novas and Vega-Mercado, 1996). Fruits (Leonid et al., 2006).

Numerous investigators have examined the hot air drying characteristics in fruits and vegetableswith a high moisture content, such as tomatoes (Orikasa et al., 2005), garden beets, carrots (Pabis and Jaros, 2002), and sweet potatoes (Orikasa et al.,2010). The disadvantages of hot air drying include its low energy efficiency and lengthy drying time during the falling rate period. Hot air also causes substantial color and nutrient degradation.

Vacuum drying is a process in which moist material is dried under subatmospheric pressure (Arevalo-Pinedo and Murr, 2006).

Freezing The effect of freezing on specific tissue within organs of other grass species has also been documented.

Mesophyll cells in maize had collapsed when frozen but bundle sheath and epidermal cells of vegetative were apparently undamaged (Ashworth and Pearce, 2002). Changes in the ultra structure of meristematic cells of tall fescue (Festucaarundinacea) that were frozen and thawed included “swelling and disruption of organelles, accumulation of osmophilic material and contraction of the nucleus” (Pearce and McDonald, 1977). The apical meristem of vegetative was the most freezing tender part of the crown in orchard grass plants that had been coldacclimated (Shibata and Shimada,1986).Freezing methods on Vegetable at the cellular level can be manifested as osmotic and oxidative stresses, which are also common responses to drought. Both freezing and drought rely on similar mechanisms that allow plants to maximize cellular stability and minimize injury associated with osmotic and oxidative stresses, and therefore significant overlap in gene regulation has been observed during exposure to both these stresses (Peng et al., 2008; Tommasini et al., 2008).

Cooking InVegetable reported Mohapatra and Bal (2006) also reported a decrease in cooking time with an increase in the degree of milling. Three varieties of rice were studied. The optimum cooking time was found out by crushing ten rice grains between two glass plates and noting down the time at which 90% of the grains were cooked. It was observed that for all the three rice varieties, as the degree of milling increased, optimal cooking time reduced. This was because, as the degree of milling increased, the amount of bran removed was also more. This resulted in faster rates of moisture absorption by rice. The results of Mohapatra and Bal (2006) are reproduced. Cheigh et al.

(1978) studied the cooking of rice milled to 3 different levels – 50%, 70% and 90% over a temperature range of 90– 120 _C. The cooking was followed by measuring the variation in the hardness of the rice grains at different times of cooking. Their results indicated that the cooking of rice was controlled by the reaction of starch with water below 100 _C and by the diffusion of water through cooked rice above 100 _C. They also reported that as the extent of milling increased the cooking time reduced at all temperatures.There are different methods for measuring

Intl J Agri Crop Sci. Vol., 7 (7), 417-421, 2014



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