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Role of serum viscosity and of pulp content in the vacuum belt drying of pure fruit juices
Author(s) -
MALTINI ENRICO,
NANI RENATO,
BERTOLO GIANNI
Publication year - 1992
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/j.1365-2621.1992.tb01219.x
Subject(s) - maltodextrin , rheology , chemistry , vacuum drying , food science , consistency index , pulp (tooth) , freeze drying , apparent viscosity , spray drying , limiting , fruit juice , chromatography , pulp and paper industry , materials science , composite material , medicine , mechanical engineering , pathology , engineering
Summary Vacuum Belt Drying of fruit juice concentrates may be a satisfactory alternative to freeze drying where cost is a limiting factor, and to spray drying where the addition of large amounts of ‘carriers’, e.g. maltodextrin or glucose syrups, are required to avoid collapse and sticking of the product. The rheological and structural properties and the drying behaviour of some juice concentrates have been studied in relation to the collapse phenomenon, which is a structure transition associated with the mechanical properties of the system. Collapse during drying has proved to be mainly related to the viscosity (consistency) of the soluble fraction of the concentrate, i.e. the ‘serum’, while there is no evidence of an effect of the suspended phase (pulp). By properly adjusting the serum consistency of the juice with selected pectolytic enzymes and by appropriate mixing of the mash derivatives, apple, pear, apricot, and peach concentrates have been successfully dehydrated by vacuum belt drying, without any addition of ‘carrier’‐supporting materials. The consistency index of the concentrate serum may be used to assess the suitability of the juice for drying.