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|Elemental Profiling of Selected Natural and Artificially Ripened Fruits to Study Variations in Minerals/Heavy Metals
|Biological & Medical Sciences
Biochemistry Molecular Biology
|Quaid-i-Azam University, Islamabad.
|Elemental analysis is a valuable tool in several disciplines including food science, soil science ecology, physiology, and agronomy. More Importantly element Profiling is becoming poular in response for accurate measurements of the elements present in trace amounts. Ash, water, soil, food and plant samples are usually analysed for the estimation of major, minor and trace elements by several techniques such as X-ray based spectroscopy, atomic spectroscopy and nuclear techniques. Highly sophisticated atomic spectroscopy techniques like Inductively Coupled Plasma Mass Spectroscopy (ICP-MS), Inductively Couple Plasma Atomic Emission Spectroscopy (ICP-AES), Graphite furnace atomic absorption spectroscopy and Flame atomic absorption spectroscopy can provide highly accurate results. However, plant samples are commonly analysed by atomic absorption spectroscopy. X-ray based spectroscopy that includes Proton Induced X-rays Emission (PIXE) and X rays Fluorescence Spectroscopy (XRF) X-ray Fluorescence Spectroscopy (XRF) are a worthy, viable, reliable and non-destructive techniques intended for trace element profiling. Analysis of trace elements of medical samples, archaeological, geological and aerosols by this technique are well known due to ability to analyse low molecular weight samples without any pre-treatment (cause of any potential cross contamination) which makes it relatively useful for several biological samples as given below. we divided this dissertation into two main parts including: Part-I aims to profile variations in mineral/heavy metals composition with special focus on detection of heavy metals in artificially ripened fruits including Peach (Prunus persica L) and Mango (Magnefera indica). Ethylene exposure for artificial fruit ripening is non toxic and human safe method but relatively cost effective due to the requirements of environmentally controlled chambers and transport technologies. Unfortunately, Calcium carbide (CaC2), due to its low cost, though banned chemical is still very popular for artificial fruit ripening purpose in many developing countries, including Pakistan. CaC2 is usually contaminated with traces of heavy metals including arsenic and phosphines and their application directly or indirectly to fruits can lead to severe human health hazards. We therefore utilized PIXE, XRF, ICP MS and GFAAS to analyze and compare elemental composition of peach and mango with and without CaC2 treatment. Fruits were categorized into five groups on the basis of CaC2 treatments (T1- T3), control without any Elemental Profiling of Selected Natural and Artificially Ripened Fruits to Study Variations in Minerals/Heavy Metals XIV treatment (T0), and fully ripened fruits from market (T4). Mango and Peach fruits were carefully analysed for the organoleptic characteristics during whole experiments and compared with control fruit samples. Fruits were cut into pieces and were dried to remove the moisture. Dried samples were grinded to fine powder. Pellets of 2 mm thickness and 13 mm diameter were prepared using Laboratory Hydraulic Press. Pulverized Mango and Peach fruit samples were irradiated by 3MeV collimated protons from 5MV tandem accelerator and emitted X-ray spectrum was analyzed using GUPIXWIN to detect amount/concentration of arsenic traces with differential presence of several other elements. PIXE elemental profiling of the fruit samples was further validated by X-ray Fluorescence Spectroscopy (XRF), Graphite Furnace Atomic Absorption Spectroscopy (GFAAS) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). All of these state of art technologies have confirmed the presence of arsenic traces in different groups (T1-T3) including market samples of mango and peach (T4). Elements detected in mango pulp were in range of (0.07-426.8 mg/kg) and correlation analysis revealed that Arsenic (As) has moderate negative correlation with potassium K (r2 = -0.5) in mango pulp. Elements detected in peach peel were in range of (0.2-413.8 mg/kg) and correlation analysis revealed that As has very strong positive correlation with copper (r2 = 0.942) moderate positive correlation with Nickel (r2 = 0.66) and Fe (r2 = 0.65) in peach peel. Elements detected in peach pulp were in range of (0.2-750 m/kg). It was noticed that peach fruit treated with CaC2 contain traces of arsenic residue only on their skin. No arsenic traces were recorded in pulp part of CaC2 treated Peach fruits. There are certain study that reports that tiny hairs on peach skin offer protective role to inner part of fruit. In present study we chose nectarines fruit which is closed to fruit both in structure and evolution. Nectarines are regarded as shaved peaches as this fruit does not contain fuss or tiny hairs on skin. So, we treated the nectarine fruit in a similar way as peaches were treated. Elemental profile of nectarine treated with CaC2 revealed that arsenic traces passed through skin and was recorded in inner part of nectarine fruit i.e. pulp. Range of estimated daily intake of arsenic in mango (0.002-0.019 mg/kg) and peach (1.4-18.6 mg/kg) was more than the WHO recommended guidelines (0.0003 mg/kg) and higher rate of such fruits consumption during season can accumulate dangerous levels of arsenic in our bodies so, this chemical should be totally ban. In order to find out the important variables and to explain the elemental relationship of under examined fruits, PCA model Elemental Profiling of Selected Natural and Artificially Ripened Fruits to Study Variations in Minerals/Heavy Metals XV was applied. The PCA analysis revealed that As residue in peach peel samples is significantly high and is closely correlated with Copper followed by iron and nickel. Furthermore, this study provides an easy and reliable method to do the fruit elemental profiling and provides a platform to develop mass awareness programs among different farmers, vendors, stakeholders, government agencies, scientist and mainly the consumer to disclose the multiple effects of artificial fruit ripening issues and the implementations of the existing rules for food quality in Pakistan. Part II, sheds light on utilization of PIXE for elemental profiling of selected fruits Apple (Malus domestica), Apricot (Prunus armeniaca L), Banana (Musa acuminata), Date (Phoenix dactylifera L) , Fig (Ficus carica), Guava (Psidium guajava), Persimmon (Diospyros kaki L), and Plum (Prunus domestica) from the different markets of Islamabad Pakistan. Mature but ready to eat fruits were purchased from market such as Aabpara Market, Itwar Bazar, Metro Super Market, Mandi Mor and Street Vendor. Fruit samples from market and control fruits were oven dried and ground to fine powder. Pellets of 2 mm thickness and 13 mm diameter were prepared using Laboratory Hydraulic Press and samples were irradiated with 3 MeV collimated protons from the 5 MV tandem accelerator. The X-rays emitted during irradiation from the samples were measured by Silicon Drift Detector (SDD) and the acquired X-ray spectrum was analysed by using the software GUPIXWIN. PIXE elemental profiling of the fruit samples was further validated by X-ray Fluorescence Spectroscopy (XRF). This state of the art technology confirmed the presence of essential mineral along with arsenic, cadmium, mercury and lead traces in different fruits from different fruit market. Results of this part showed that all fruit contained significant concentrations of these essential minerals. Heavy metal such as arsenic was detected in every fruit sample except Persimmon and fruit from Aabpara Market was likely to contain arsenic in almost significant amount. Mercury was detected in Guava, Persimmon, Date and Plum and fruit from Madi Mor contained mercury in significant amount.Cadmium was detected in Apricot, Apple and Fig and fruit from Aabpara Market contain cadmium in almost significant amount.Similarly Lead was detected in Plum and Persimmon and fruit from Aabpara Market showed traces. Present study results revealed the range of EDI (mg/kg bw day) of the Cr which as normal or with in the permissible limits in guava, Banana, Date, Fig, Apple and Apricot while in Persimmon and Plum it was 35-176.14 mg/kg bw day and 80.57-137.24 mg/kg Elemental Profiling of Selected Natural and Artificially Ripened Fruits to Study Variations in Minerals/Heavy Metals XVI bw day respectively. HI and THQ was less than 1 for Cr for all fruit samples. Consequently, the intake of these foods does not pose health risks associated with the toxicity of Cr. Arsenic was detected in Guava, Banana, Date, Plum, Fig, Apple and Apricot. THQ value for arsenic was calculated less than 1 in all fruits except in guava where THQ of arsenic was in range of 1.8-3.2. These results showed that arsenic contaminated Guava fruit can pose serious health hazard to consumers. Mercury was detected in Persimmon Fig and Date fruits but their THQ value for mercury was calculated less than 1. Therefore, the ingestion of these foods does not pose health risks associated with the toxicity of Hg. Similarly Cadmium was detected in Fig Apricot and Apple fruits but their THQ value for mercury was calculated less than 1. Therefore the consumption of these foods do not pose health risks related to Cd toxicity. Lead was detected in Persimmon and Plum fruits but their THQ value for lead was calculated less than 1. Consequently, the intake of these foods presents no health hazards associated with the toxicity of Pb. The present study revealed that the presence of heavy metals in selected fruits from market is related to artificial ripening agents which are the main cause of deposition of these heavy metals more than their upper limits in the fruits. Furthermore, based on the research utcomes we suggest the food regulating authorites to take controlling measure against the different types of fruit ripening in Pakistan and there is an imminent need to develop the guidelines for the use artificially ripened agent in markets and its permissible exposure limits for various fruits ripening conditions for different agriculture practices. Further studies are required therefore to call the active involvement of politicians, government agencies, producer, manufacturer, scientists and consumers in addressing various aspects of artificial fruit ripening. The promotion of use of there state of the art analysis will definitely contribute to development of field. Moreover, a close collaboration between physicists and specialists from plant sciences is the key to success in this multidisciplinary research.
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