Influence of Thermal Processing on Hydrolysis and Stability of Folate Poly-γ-glutamates in Broccoli (Brassica oleracea var. italica), Carrot (Daucus carota) and Tomato (Lycopersicon esculentum)
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Date
2010
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of agricultural and food chemistry
Abstract
The folate poly-γ-glutamate profile, their concentrations, and hydrolysis by endogenous γ-glutamyl
hydrolase (GGH) were evaluated in broccoli, carrot and tomato. Further studies on the effect of time
and temperature on folate poly-γ-glutamate hydrolysis and stability were carried out in broccoli since
this vegetable showed the highest long-chain and total folate poly-γ-glutamate concentration. The
evolution of L-ascorbic acid, total phenols and Trolox equivalent antioxidant capacity (TEAC) values
was evaluated in parallel. Upon thermal inactivation of GGH prior to crushing, it was observed that
broccoli, carrot and tomato contained poly-γ-glutamates with one to seven glutamate residues but
differed in the predominant poly-γ-glutamates. Crushing of raw broccoli, carrot and tomato resulted
in significant poly-γ-glutamate profile changes in broccoli and carrot (indicating GGH-catalyzed
hydrolysis) but not in tomato. In this study, the actual crushing of raw broccoli matrix had a greater
effect on folate poly-γ-glutamate hydrolysis than incubation conditions (0-30 min at 25-55 C).
During treatments at 25-140 C, folate retention was higher at 80 and 100 C than at the other
temperatures. A similar trend in thermal stability was observed for folates, vitamin C, total phenols
and TEAC value, an indication that conditions that result in endogenous antioxidants degradation
might also result in folate degradation.The folate poly-γ-glutamate profile, their concentrations, and hydrolysis by endogenous γ-glutamyl
hydrolase (GGH) were evaluated in broccoli, carrot and tomato. Further studies on the effect of time
and temperature on folate poly-γ-glutamate hydrolysis and stability were carried out in broccoli since
this vegetable showed the highest long-chain and total folate poly-γ-glutamate concentration. The
evolution of L-ascorbic acid, total phenols and Trolox equivalent antioxidant capacity (TEAC) values
was evaluated in parallel. Upon thermal inactivation of GGH prior to crushing, it was observed that
broccoli, carrot and tomato contained poly-γ-glutamates with one to seven glutamate residues but
differed in the predominant poly-γ-glutamates. Crushing of raw broccoli, carrot and tomato resulted
in significant poly-γ-glutamate profile changes in broccoli and carrot (indicating GGH-catalyzed
hydrolysis) but not in tomato. In this study, the actual crushing of raw broccoli matrix had a greater
effect on folate poly-γ-glutamate hydrolysis than incubation conditions (0-30 min at 25-55 C).
During treatments at 25-140 C, folate retention was higher at 80 and 100 C than at the other
temperatures. A similar trend in thermal stability was observed for folates, vitamin C, total phenols
and TEAC value, an indication that conditions that result in endogenous antioxidants degradation
might also result in folate degradation.
Description
Keywords
Antioxidants, Crushing, Broccoli, Carrot
Citation
Munyaka, AW, Verlinde, P., Mukisa, IM, Oey, I., Van Loey, A., & Hendrickx, M. (2010). Influence of Thermal Processing on Hydrolysis and Stability of Folate Poly-γ-glutamates in Broccoli (Brassica oleracea var. italica), Carrot (Daucus carota) and Tomato (Lycopersicon esculentum). Journal of agricultural and food chemistry , 58 (7), 4230-4240. DOI:10.1021/jf100004w