Abstract:
Black pepper (Piper nigrum L.) is an important spice. The adulteration of black pepper seeds
and powder with papaya seeds, green chili and red chili can be seen and limited studies have
been conducted to detect these adulterants. The objectives of the present study were to assess the
appropriateness of morphometric methods to discriminate papaya seed and chili adulterations
in black pepper and to establish a DNA based strategy to detect these adulterations. A necessary
adulteration series of seeds and powders were prepared for the analyses along with commercial
samples. The appearance of the seed and powder samples were slightly different but not very
distinct among the pure and adulterated samples emphasizing the need of a biochemical approach
to detect the adulteration. The adulterated and commercial black pepper samples received lower
pungency ranks compared to that of pure samples. QIAGEN DNeasy® Plant Mini Kit was successful
in extracting PCR amplifiable DNA from any sample without papaya seeds and the modified CTAB
method was able to extract required PCR amenable DNA from any sample with papaya seed
material. The universal DNA barcoding primer pair, psbA-trnH, was used to amplify the DNA.
Black pepper DNA yielded 200 bp band, chili and papaya DNA yielded 450 bp band and DNA
from adulterated samples produced both 200 bp and 450 bp bands. Therefore this strategy can be
used to detect papaya / chili adulterations in black pepper.
