Viscosity as Affected by Various Constituents of Tomato Juice

Abstract

SUMMARY— Degradation of proteins of tomato juice with pronase caused a relatively small loss of viscosity. Commercial cellulase freed of pectolytic activity with 8 M urea greatly decreased the viscosity of washed tomato solids. Further degradation with pectinase was ineffective in reducing viscosity. Cellulase extracted from the tomato lowered viscosity of tomato juice. Enzymatic degradation as indicated by chemical analysis did not always result in a loss of viscosity. By extracting the solids with water, viscosity of tomato juice was lowered drastically. The extent of the reduction was not affected by previous treatment with cellulase or pectinase. Viscosity was not affected by extraction with versene. The greater reduction in viscosity of tomato juice by extraction of the solids with water than with ethanol indicates that the high molecular polymers associated with the insoluble solids contribute greatly to viscosity. The data did not indicate a significant contribution of the uronides to the viscosity of tomato juice.

Enzymatic cell wall degradation of high‐pressure‐homogenized tomato puree and its effect on lycopene bioaccessibility

“…These results are in agreement with previous studies reporting a reduced viscosity of tomato juices on adding cellulases and pectinases . These authors established that polymeric compounds such as pectin and cellulose contribute majorly to the consistency of tomato juices.…”

Evaluation of processing qualities of tomato juice induced by thermal and pressure processing

“…Some researchers reported that when using hot-break method, the temperatures are high enough for pectolytic enzyme inactivation, and this leads to a concentrate of greater viscosity (Fito, Clemente, & Sanz, 1983;Goodman et al, 2002). In addition, break temperature influences the viscosity of tomato products by changing pectin retention (Xu, Shoemaker, & Luh, 1986), but the effect was eliminated due to the insignificant contribution of pectins to the viscosity of tomato juice (Foda & McCollum, 1970). Therefore, this study mainly showed that viscosity differences are caused by enzyme activity.…”

Technical note: Effect of low pH preservation on the colour and consistency of tomato juice

“…The higher consistency of the low pH sample may be due to two reasons: (a) the increased pectin contents (0.31%) or (b) the presence of increased levels of low methoxyl pectin in this sample. Higher levels of pectic substances have been demonstrated to increase the consistency of tomato juice by a number of workers (McColloch, Keller & Beavans, 1952;Hand et af., 1955;Foda & McCollum, 1970). According to Padiwal, Ranganna & Manjrekar (1979), the gel formation involves the transformation of a sol state of Low Methoxyl Pectin (LMP) to the gel state caused by added calcium.…”