Table 11. Difference of heavy metals content in green beans and roasted coffee beans

	No. of samples	Pb (mg/kg)	Cd (mg/kg)
		Mean ± S.D. (min. – max.)	Mean ± S.D. (min. – max.)
Total	79	0.052 ± 0.061 (0.000 – 0.393)	0.006 ± 0.006 (0.000 – 0.028)
Green bean	24	0.014 ± 0.020 (0.000 – 0.073)	0.002 ± 0.003 (0.000 – 0.012)
Roasted coffee bean	55	0.069 ± 0.066 (0.000 – 0.393)	0.008 ± 0.006 (0.001 – 0.028)

Means within a vertical column are significantly different by independent t-test (p<0.05).