NAMS 2002 Workshop - ICOM 2008

Pervaporation and Vapor Permeation III – 3
Friday July 18, 3:30 PM-4:00 PM, Kaua’i
Effect of Feed Solution Characteristics on Flavour Concentration by
Pervaporation
A. Overington (Speaker), Institute of Food, Nutrition and Human Health, Massey University,
Palmerston North, New Zealand - Amy.Overington@fonterra.com
M. Wong, Institute of Food, Nutrition and Human Health, Massey University, Palmerston North,
New Zealand
J. Harrison, Institute of Fundamental Sciences, Massey University, Palmerston North, New
Zealand
L. Ferreira, Fonterra Co-operative Group Ltd., Auckland, New Zealand
Organophilic pervaporation can potentially be used in the food industry to recover
flavours that would otherwise be lost, and to create natural flavour concentrates.
Trials with model solutions often show that flavour compounds can be highly
enriched using pervaporation, but there has been little research on how the
process is affected by non-volatile substances found in foods, such as fat, protein
and carbohydrates. These components cannot pass through pervaporation
membranes, but they can interact with flavour compounds in the feed.
The driving force for pervaporation depends on the activity of each permeant on
the feed side of the membrane. Non-volatile feed components can either
increase or decrease permeant activities, following various mechanisms. In a
food product that contains fat, flavour compounds will partition between the
aqueous and fat phases. The partition coefficient between the two phases
depends on the compound. The portion of each compound in the fat phase is
effectively unavailable for pervaporation. Protein and carbohydrates can also
alter flavour compound volatility by different amounts depending on the
compound, thereby changing the driving force for pervaporation of these
compounds. The driving force of acidic compounds is also affected by the feed
pH.
To bridge the gap between model solution trials and pervaporation of real food
products, it is important to understand how feed solution characteristics affect
pervaporation. This presentation presents results from the pervaporation of
selected flavour compounds (homologous series of organic acids, esters and
ketones) in feed solutions containing dairy ingredients (cream, lactose and milk
protein).