According to Malaysian Food Regulation 1985 and Malaysia
Standard MS2334:2011, raw edible bird’s nest which undergone
cleaning process should not contain more than 30
ppm of nitrite contents. The nitrite contents obtained in cave
nests, C1–C4, were 2700% higher than the allowed limit. This
result is consistent with Paydar et al.’s [16] and Chan et al.’s
[12] work who mentioned that cave nests contained significantly
higher nitrite and nitrate levels compared to the
house nests [12,16]. This is because the swiftlet houses are
well-managed by frequent cleaning of the bird soil and guano
whereas the cave guanos are left all over in the caves. In general,
the bird soil and guano can generate nitrite and nitrate
through fermentation process, so they should be routinely
removed to control the nitrite and nitrate contents in edible
bird’s nests. The good ventilation in the swiftlet houses also
helped to reduce the fermentation process and hence the
house nests had relatively low nitrite and nitrate contents
compared to cave nests. The results showed a large standard deviation of mean within the two types of nests, house nests
and cave nests. These differences were reflected by the wide
variability of edible bird’s nests. These variations may be
attributed to the swiftlet habitat environment such as humidity,
temperature, and pH [3] and harvest time of edible bird’s
nests.