Determination of Heavy Metals in Canned Dry-Milk and Fish from - PowerPoint PPT Presentation

Determination of Heavy Metals in Canned Dry-Milk and Fish from Supermarkets in Addis Ababa, Ethiopia Kefyalew Muleta Tetemke Mehari (PhD) 1

PRESENTATION OUT LINE  Introduction  Objective  Material and Methods  Results and Discussion  Conclusion and Recommendation  Acknowledgment 2

1. Background • Food quality depends on the composition and chemical nature of its components (McElhatton, 2007). • Minerals such as Cu and Zn which are required up to a limits. • The metals Cd and Pb enter food as a result of human activities, can be harmful to health (Neustacdt et al., 2007). 3

Background cont … • Milk and fish might be contaminated due to: o Feeding of cattle on contaminated feed (for milk) (Miranda et al., 2005) o Food processing equipments and canning processing o Storage condition might favors the leakage of heavy metal to the foods (Buldini et al ., 2002) 4

Background cont… More than 9 thousands tons of canned fish and 2 thousands tons of canned powder milk are imported to Ethiopia in a year. More than 200 supermarkets commercialize canned dry-milk and fish in Addis Ababa (AABT, 2013). But no evidence of chemical safety of canned foods. 5

Objective of the Study 1. To determine the concentration of Cadmium, Copper, Lead and Zinc residues in four brands of canned dry- milk. 2. To determine the concentration of Cadmium, Copper, Lead and Zinc residues in four brands of canned fish. 3. To compare the labeled nutritional information to determined values of the foods. 6

2. MATERIALS AND METHODS • The study was conducted on canned dry-milk and fish from supermarkets in Addis Ababa from February to march, 2013 • Laboratory based cross-sectional study design • Heavy metals (Cd, Cu, Pb and Zn) and proximate analysis were done. 7

Sampling Design Canned foods Canned Canned dry milk fish Chiara Delight Diamond Abay milk Coast milk Nido milk France lait Nicola fish tonno fish fish fish 8

Canned Dry-Milk Sample The following four brands of canned dry-milk: No Dry-Milk Code Brand 1 Abay milk AM 2 Coast Milk CM 3 France Lait FM 4 Nido Milk NM 9

Canned Fish-Sample The following four brands of canned fish: No Fish Brand Code 1 Chiara Tonno CF 2 Delight DF 3 Diamond DIF 4 Nicola NF 10

Metal Extraction Procedure (Wet Digestion) Double cans of each brands Homogenized by stainless homogenizer Duplicate of 2.00 ± 0.01 g milk sample Mixture of HNO3 and H2O2 in Duplicate of 5.00 ± 0.01 g fish sample 5:1 ratio Digested on hot plate at 240 ºc for 4 hours for canned fish 300 ºc for 6 hours for dry-milk Cooled, filtered by whatt-man filter paper and made-up to 50mL volume Blank, and Pb and Cd Spiked were run to evaluate the reliability of the procedures (AOAC, 1990). 11

Proximate Analysis • Protein, fat, ash, moisture content analysis were done according to the AOAC, 2000.; • Carbohydrate for canned dry-milk were determined by difference method. 12

Statistical Analysis • Data analysis was computed using version 20 SPSS and Microsoft Office Excel 2009 software. • Range, mean ± SD was used to express the concentration of each heavy metals and proximate value. 13

Cont… Statistical Analysis • Two-side student t-test was used to compare the nutritional label value to determined once. • One-way ANOVA was used to test the variability samples among brands, at 95% confidence level. 14

Instrumental (AAS) Analysis • All the samples were analyzed for their Cd, Cu, Pb, and Zn residue level using Flame Atomic Absorption Spectrophotometer (FAAS) at Debrezeit ARC, ECAE, and AAEPA. 15

Table 2 :The following wave lengths were used for each metals Heavy Metals Cd Zn Cu Pb Wavelength (nm) 228.8 213.9 324.8 217 Slit width (nm) 0.5 1.0 1.0 1.0 Coefficient of determination 0.99 0.99 0.99 0.99 (R 2 ) 16

Cont… AAS Analysis • Concentration working standards were used to calibrate the AAS at: • 0.25, 0.5, 1 and 2 mg/L for Cu, Cd and Zn • 0, 0.5, 1, 2, and4 mg/L were used for Pb 17

Instrument calibration for each metals 0.12 0.2 y = 0.1001x - 0.0183 y = 0.0244x + 0.0011 0.1 R² = 0.987 R² = 0.9943 0.15 0.08 Absorbance 0.06 0.1 y = 0.0556x - 0.0161 Absorbance R² = 0.9919 Cd 0.04 0.05 Cu 0.02 Zn y = 0.042x + 0.0064 0 R² = 0.997 0 0 1 2 3 0 2 4 6 -0.05 Concentration Concentration Fig 3: FAAS Calibration Curve for Cd, Cu and Fig 4: Calibration Standard Curve Zn for Pb They obey beer’s law. 18

Table 3 : Limit of detection (LOD) and limit of quantification (LOQ) in mg/g Blank code Cu Zn Cd LOD 0.27 5.19 0.23 LOQ 0.91 17.33 0.76 19

3. RESULTS AND DISCUSSION Table 1 : General information of sampled canned dry-milk from supermarkets in Addis Ababa, 2013. Brand Country of net wet Fat Protein CHO Energy Yield Code origin (g) (Kcal/KJ) AM Ethiopia 400 28.8 24.5 38.3 510/2130 Holland 400 28 26 37.2 510/2140 CM Netherland 400 28.2 24 37.4 508/2120 NM FM France 375 26.2 26 38.6 494/2067 CHO: Carbohydrate in g/100g 20

Table 4 : Comparison of level of heavy metals in four brands of canned dry-milk from supermarkets in Addis Ababa, 2013. Brand Level of heavy metal in canned dry-milk brands (mg/g in wet-base) code Cu Zn Cd Pb 1.053±0.314 ab 21.307±8.796 a 0.202±0.309 b 5.374±2.048 a AM 1.512±0.954 a 17.039±3.335 a 1.991±0.47 a 8.077±2.094 a CM 0.88±0.769 ab 16.177±1.528 a 1.885±0.336 c 5.921±5.045 a FM 0.094±0.074 b 23.679±1.359 a 1.114±0.878 abc 15.999±8.392 a NM AML 10 150 0.2 1.5 ND: Not Detected AML: Allowable Maximum Limit according to FAO/WHO, 1984 in ppm At each level of parameter, the mean with different superscript in the same column are significantly different at P=0.05 level. 21

Cont…… • The lowest Cd level (0.202 ± 0.309 mg/g) in AM milk branded is comparable with the values of Cd contents (0.2 ± 0.008 mg/g) in four brands of unlacquered canned milk studied in Nigeria by Adams and Happiness (2010) . • The lowest Pb level (5.921 ± 5.045mg/g) of AM milk brand from France was lower than Pb value (11.2 + 0.48 mg/g) by Adams and Happiness, (2010) in Nigeria. 22

• The concentration of Zn, Cd and Pb in all the milk brands of this study were four to six folds higher than mean level, 4.92, 0.1, and 0.99 mg/g respectively, in cow’s whole milk from different areas in Addis Ababa studied by Gashu et al., 2010). 23

Table 5 : Comparison of labeled and observed nutritional value in percent (wet-base) (mean ± SD in %) of dry-milk from supermarkets in Addis Ababa, 2013. Brand Fat Protein Carbohydrate code Determined Labeled Determined Labeled Determined Labeled 5.125 ± 2.136 a 28.8 b 16.635 ± 5.393 a 24.5 a 70.516 ± 5.607 r 38.3 s AM 2.715 ± 0.257 h 28 b 8.021 ± 0.199 b 26 c 88.530 ± 4.212 t 37.2 a CM 3.625 ± 1.25 m 26.2 n 17.133 ± 1.753 d 26 e 73.523 ± 2.818 b 38.6 c FM 3.375 ± 2.213 p 28.2 q 16.327 ± 4.267 f 24 g 73.877 ± 6.237 d 37.4 e NM At each level of parameter means in the same row with the different superscripts are different at 0.05 significantly level. 24

Table 6 : Comparison of labeled and observed energy value (wet- base) (mean+SD) of dry-milk from supermarkets in Addis Ababa,2013. Dry-Brand Energy yield in kcal/g Percent code difference Determined Labeled a b AM 394.730 ± 10.201 510. 22.602 c d CM 410.635 ± 15.998 510 19.483 e f FM 395.248 ± 7.503 494 19.990 b a NM 391.191 ± 11.732 508 22.994 Mean values with different superscript in same row are significantly different at 95%. 25

Table 12 : General information of the sampled canned fish from supermarkets in Addis Ababa, 2013. No. Brand No. of can Country of origin Packed in Net wet(g) Code 1 CF 2 Spain Sunflower oil 80 2 DF 2 Vietnam Brine 170 3 DIF 2 Thailand Sunflower oil 185 4 NF 2 Indonesia Vegetable oil 125 26

• All the cans have manufacture and expiration date . • Three cans were well labeled for their nutritional values but the DF brand, packed in brine, imported from Vietnam don’t have labeling for their nutritional values. • One of the CF brand packed in sunflower oil imported from Spain was dented at its sides. 27

Table 13: Concentration of heavy metals (mean ± SD and range) in wet weight base in canned fish from supermarkets in Addis Ababa, 2013. Samp Packed in Level (mg/g) le Code Cd Cu Pb Zn 3.541±2.467 a 3.004±1.809 a 33.897±3.670 a CF Sunflower oil 6.574±2.899a 1.863±0.243 a 0.68±0.449 b 4.447±1.087 a DF Brine ND 2.174±0.559 a 0.319±0.232 b 1.976±0.868 a DIF Sunflower oil 5.185±0.000a 0.381±0.274 a 0.864±0.1 ab 0.08±.004 a NF Vegetable oil 1.791±0.275a MTL 0.2 10 1.5 150 In each level of parameter the means with different superscript are significantly different at the 0.05 level. ND: Not Detected MTL: Maximum Tolerable Limit according to FAO/WHO 1984. 28

• The levels of Cd in the four brands of fish were higher than: – (0.13 ± 0.04 mg/kg) in canned Bluefin tuna Thailand and – (0.053 ± 0.005 mg/kg) in canned Bluefin tuna Korea, study by Islam et al., 2010 • But Cd level in all the fish (except the CF) were lower than:  20 mg/g, a study by Tuzen, 2003 in fish from Turkey;  Canned tuna from US (1.9 mgg -1 ), study in India by Balakrishnan et al., 2011. 29