Premium
Kinetics of the inactivation of polyphenol oxidase and formation of reducing sugars in sugarcane juice during Ohmic and conventional heating
Author(s) -
Saxena Juhi,
Makroo Hilal Ahmad,
Bhattacharya Suvendu,
Srivastava Brijesh
Publication year - 2018
Publication title -
journal of food process engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 45
eISSN - 1745-4530
pISSN - 0145-8876
DOI - 10.1111/jfpe.12671
Subject(s) - chemistry , browning , polyphenol oxidase , kinetics , nuclear chemistry , analytical chemistry (journal) , reaction rate constant , joule heating , food science , enzyme , chromatography , organic chemistry , peroxidase , materials science , quantum mechanics , composite material , physics
Enzymatic browning and jaggery formation are the major issues that limit the applications of thermal treatment to sugarcane juice. Kinetics of polyphenol oxidase (PPO) inactivation and formation of reducing sugar (RS) during conventional heating (CH) and Ohmic heating (OH) of sugarcane juice were investigated. The CH treatment was varied from 60 to 90 °C for 300–1,200 s and OH treatment from 24 to 48 V/cm electric field strength (EFS) for 15–75 s at 80 ± 1 °C. PPO inactivation kinetics followed the n th‐order ( n = 1.6) for CH while the two‐fraction model was suitable during OH treatment. The inactivation constant k showed a reciprocal quadratic dependency on EFS and temperature. The D ‐value for CH varied between 2,635 and 359 s, and for OH, it was between 42 and 96 s for labile and between 0.007 and 0.30 s for stable PPO fractions. The temperature sensitivity ( Z T ) of PPO was 32.6 °C for CH system; the electric field sensitivities for OH treatment for labile ( Z V,L ) and stable ( Z V,S ) fractions of PPO were 69.8 and 15.6 V/cm, respectively. The calculated temperature coefficient ( Q 10,T ) was 2.12, and its analogous electric field coefficients ( Q 8,V ) for labile and stable PPO fractions were 1.28 and 3.00, respectively. The RS formation was low in the range of temperature used during CH treatment but followed the second‐order kinetics during OH system, while the formation rate followed the quadratic dependence. Practical applications Sugarcane juice is one of the natural refreshing summer drinks in several tropical countries. The processing of sugarcane juice by Ohmic heating (OH) may be a pragmatic alternative method to preserve the fresh juice. The use of Ohmic heating can reduce the treatment temperature of the juice leading to improved quality attributes in the finished product. The inactivations of polyphenol oxidase and sugar inversion due to processing treatments is the two important criteria in such products.