Enzyme profiling of floral nectar, honey bee gut secretion and honey

Abstract

The study on ‘Enzyme profiling of floral nectar, honey bee gut secretion and honey’ was carried out at Quality control lab for honey, AICRP on Honey bees and Pollinators, Department of Entomology, College of Agriculture, Vellayani during the period 2022-2024. The main objective of the study was enzyme profile comparison of floral nectar and pollen, gut secretions of Indian honey bee (Apis cerana Fabricius), raw honey from different bee species, processed honey and market samples of honey. Activity of enzymes like diastase, invertase, glucose oxidase and catalase profiling during nectar to honey transformation of Indian bee (Apis cerana) (Hymenoptera; Apidae) in two predominant nectar sources, pumpkin and rubber was done. Results of the study revealed higher activity of all the enzymes analyzed in honey stomach content in both pumpkin (43.82 DN, 56.72 IN, 21.88 GLOx and 9.52 CAT) and rubber (42.91 DN, 56.16 IN, 20.98 GLOx and 12.26 CAT) derived samples. Lowest activity of diastase, invertase and glucose oxidase was found in pumpkin pollen and extra floral nectar of rubber, while catalase showed lowest activity in head gland secretions in both cases. Highest catalase activity was noticed in plant derived samples like nectar (4.53 Ug-1) and pollen (6.44 Ug-1). Higher enzyme activity was noticed in pumpkin honey on comparison with rubber honey, making it superior among two. Determination of enzyme activity in raw honey samples of Indian bee honey, western bee honey, rock bee honey and stingless bee honey showed higher activity of diastase, invertase, glucose oxidase and catalase in stingless bee honey (58.53 DN, 49.35 IN, 23.06 GLOx and 21.87 CAT), while the lowest activity was found in Indian bee honey (32.96 DN, 36.24 IN, 16.45 GLOx and 15.86 CAT). Enzymes in processed honey samples showed higher activity of all the enzymes in machine processed rubber honey (26.15 DN, 25.56 IN, 14.33 GLOx and 13.75 CAT) and lowest activity was observed in manually processed rubber honey (24.64 DN, 22.45 IN, 11.86 GLOx and 12.53 CAT). All the processed samples showed a significant reduction in ii the enzyme activity compared to their raw samples. Saffola honey showed higher enzyme activity among the nine market samples analyzed. All the nine samples satisfied FSSAI honey standards (DN ≥3) whereas, four among the nine samples satisfied the codex alimentarius honey standards (DN ≥8). Enzyme analysis in adulterated raw honey of Indian bee, western bee, rock bee and stingless bee, adulterated with 50 % sugar syrup showed a reduction in enzyme activity with a sudden decrease in the first 24 h. Decline in enzyme activity was less in adulterated stingless bee honey compared to other three samples. Indian bee honey treated at different temperatures (30 °C, 60 °C, 90 °C and 120 °C) revealed a reduction in enzyme activity with increase in temperature and at 120 °C activity of all the enzymes was negligible. To conclude, enzyme activity during nectar to honey transformation confirms the source of diastase, invertase and glucose oxidase as head glands and catalase as plant origin. Enzyme studies on raw honey samples showed stingless bee honey as superior with highest enzyme activity followed by western bee honey. Moreover, all the market samples analyzed satisfied FSSAI standards.