Honey amylase and the effect in starch-containing foods
Honey amylase was evaluated for potential to degrade food starch and cause viscosity loss. Honey was assayed for amylase activity with diastase number (DN). A viscosity assay, developed with unmodified waxy maize starch, measured rate of viscosity decrease (RVD) by honey amylase. The relationship between DN and RVD was linear (R2 = 0.98). Modified waxy maize starches showed resistance to honey amylase. Heat treatment at 85°C reduced the amylase activity in honey, but confirmed enzyme heat resistance. Optimum pH for honey amylase was confirmed at pH 5.3–5.6. Lower pH was effective at decreasing enzyme activity in both pure starch and food systems. Preventing food viscosity loss involved selecting honey with lowered DN and/or using modified starches. Complete control of activity was achieved in barbecue sauce at pH < 3.9. ^ The major amylase in honey was purified by gel filtration followed by ion exchange chromatography. The enzyme was an α-amylase with a molecular weight of 57,000 daltons on SDS-PAGE. The optimum pH range and the temperature for the enzyme were 4.6–5.3 and 55°C, respectively. The enzyme was stable at pH values from 7 to 8. The half-lives of the purified enzyme at different temperatures were determined. Starch had a protective effect on amylase while 0.4 mM CaCl2 did not have any effect. The activation energy for the heat inactivation was 114.6 kJ/mol. The enzyme exhibited Michaelis-Menten kinetics with soluble starch and gave KM and Vmax values of 0.72 mg/mL and 0.018 units/mL, respectively. The enzyme was inhibited by CuCl (34.3%), MgCl2 (22.4%), HgCl2 (13.4%) while CaCl 2, MnCl2 and ZnSO2 did not have any effect. The results indicated that amylase in honey had a high degree of similarity with the bee-amylase and bees could be the source of this enzyme. ^ The stabilizing effect of starch suggested that it might be critical to process foods containing honey before the introduction of starch. One step could involve heating honey with ingredients that would dilute and acidify the honey environment. This treatment would utilize controls for honey amylase, since the enzyme was less heat resistant in a more isolated/diluted form and less stable in an acidic environment. ^
Agriculture, Food Science and Technology
"Honey amylase and the effect in starch-containing foods"
Dissertations and Master's Theses (Campus Access).