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

Transcription

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

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

3 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

4 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

5 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

6 Objective of the Study 1. To determine the concentration of Cadmium, Copper, Lead and Zinc residues in four brands of canned drymilk. 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

7 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

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

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

10 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

11 Metal Extraction Procedure (Wet Digestion) Double cans of each brands Homogenized by stainless homogenizer Duplicate of 2.00 ± 0.01 g milk sample Duplicate of 5.00 ± 0.01 g fish sample Mixture of HNO3 and H2O2 in 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

12 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

13 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

14 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

15 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

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

17 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

18 Absorbance Absorbance Instrument calibration for each metals y = x R² = y = x R² = y = x R² = y = 0.042x R² = Concentration Cd Cu Zn Concentration Fig 3: FAAS Calibration Curve for Cd, Cu and Zn Fig 4: Calibration Standard Curve for Pb They obey beer s law. 18

19 Table 3: Limit of detection (LOD) and limit of quantification (LOQ) in mg/g Blank code Cu Zn Cd LOD LOQ

20 3. RESULTS AND DISCUSSION Table 1: General information of sampled canned dry-milk from supermarkets in Addis Ababa, Brand Country of net wet Fat Protein CHO Energy Yield Code origin (g) (Kcal/KJ) AM Ethiopia /2130 CM Holland /2140 NM Netherland /2120 FM France /2067 CHO: Carbohydrate in g/100g 20

21 Table 4: Comparison of level of heavy metals in four brands of canned dry-milk from supermarkets in Addis Ababa, Brand code Level of heavy metal in canned dry-milk brands (mg/g in wet-base) Cu Zn Cd Pb AM 1.053±0.314 ab ±8.796 a 0.202±0.309 b 5.374±2.048 a CM 1.512±0.954 a ±3.335 a 1.991±0.47 a 8.077±2.094 a FM 0.88±0.769 ab ±1.528 a 1.885±0.336 c 5.921±5.045 a NM 0.094±0.074 b ±1.359 a 1.114±0.878 abc ±8.392 a AML 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

22 Cont The lowest Cd level (0.202 ± mg/g) in AM milk branded is comparable with the values of Cd contents (0.2± 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 ( mg/g) by Adams and Happiness, (2010) in Nigeria. 22

23 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

24 Table 5: Comparison of labeled and observed nutritional value in percent (wet-base) (mean ± SD in %) of dry-milk from supermarkets in Addis Ababa, Brand code Fat Protein Carbohydrate Determined Labeled Determined Labeled Determined Labeled AM ± a 28.8 b ± a 24.5 a ± r 38.3 s CM ± h 28 b ± b 26 c ± t 37.2 a FM ± 1.25 m 26.2 n ± d 26 e ± b 38.6 c NM ± p 28.2 q ± f 24 g ± d 37.4 e At each level of parameter means in the same row with the different superscripts are different at 0.05 significantly level. 24

25 Table 6: Comparison of labeled and observed energy value (wetbase) (mean+sd) of dry-milk from supermarkets in Addis Ababa,2013. Dry-Brand Energy yield in kcal/g Percent code Determined Labeled difference AM ± a 510. b CM ± c 510 d FM ± e 494 f NM ± b 508 a Mean values with different superscript in same row are significantly different at 95%. 25

26 Table 12: General information of the sampled canned fish from supermarkets in Addis Ababa, 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 DIF 2 Thailand Sunflower oil NF 2 Indonesia Vegetable oil

27 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

28 Table 13: Concentration of heavy metals (mean± SD and range) in wet weight base in canned fish from supermarkets in Addis Ababa, Samp le Code Packed in Level (mg/g) Cd Cu Pb Zn CF Sunflower oil 3.541±2.467 a 3.004±1.809 a 6.574±2.899a ±3.670 a DF Brine 1.863±0.243 a 0.68±0.449 b ND 4.447±1.087 a DIF Sunflower oil 2.174±0.559 a 0.319±0.232 b 5.185±0.000a 1.976±0.868 a NF Vegetable oil 0.381±0.274 a 0.864±0.1 ab 1.791±0.275a 0.08±.004 a MTL 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

29 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.,

30 The lowest level of Pb (1.791±0.275mg/g) in NF fish brand from Indonesia which is lower than: Pb level (2.9 mg/g) in canned tuna fish from Libya (Voegborlo et al., 1999), and 1.95 mg/g in canned fish from Turkey (Celik and Oehlenschlager, 2006). 30

31 The levels of Cd (1.13 mg/kg) and Pb (2.20mg/kg) in fish from Hawassa and Ziway lakes (Kiflom, 2011) were higher than the NF brand from Indonesia. The levels of the four heavy metals in CF brand packed in sunflower oil were relatively higher than the other three brands. This might be due to the dented can may leak heavy metals to the food. 31

32 Table 15: Fat, protein (g/g) and energy yield (kcal) content in gram (mean± SD) (wet-base) of canned fish from supermarkets in Addis Ababa, 2013 Samp le ID sample Fat content Protein content Energy value Determined Labeled Determined Labeled Determined Labeled CF ± a 21 b ±1.486 a 22.5 b ±4.773 a 279 a DIF ± c 9 d ±1.234 i 27.1 j ±5.504 a 189 b NF ± e 18 f ±0.868 a 23 b ±12.54 c 254 d At each level of parameter the mean with different superscript in the same row are significant different at 0.05 levels. 32

33 5. CONCLUSIONS AND RECOMMENDATIONS From this study, it can be concluded that: 1. The canned dry-milk brands determine level of Cd and Cu residues significantly vary among. 2. All brands were not safe in their Pb level. 3. Only, the AM milk brand from Ethiopia was safe in Cd level. 33

34 Cont. Conclusions 4. The levels of Cu residue s vary among brands of canned fish. 5. The three fish brands, CF, DF and DIF were not safe in their Cd residue level. 6. But the Cd and Pb level in the NF fish brands and the Pb level in DF brand were safe. 7. Canned dry-milks were good sources of Zn than canned fish. 8. Labeled and determined nutritional values of NF and DIF fish brands, and all canned dry-milk brands were different. 34

35 Recommendations Determining the concentration of heavy metals and nutritional values in canned dry-milk and fish should be done periodically by the responsible organization to make sure that imported foods are safe for the public. 35

36 Acknowledgment Addis Ababa University, Center for Food Science and Nutrition, Debrezeit Agricultural Research Center, Ethiopian Public Health Institute 36

37 Thank You! 37