WATER REFERENCE

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REPRINTS, COPIES
Lomauro, C.J., A.S. Bakshi and T.P. Labuza. 1985. Evaluation of food Moisture Sorption Isotherm Equations. Part I: Fruit, Vegetable and Meat Products. Lebensm.-Wiss u.-Technol. 18:111-117.

Purpose: The purpose of this study was to summarize and evaluate food isotherms.
Abstract:Three two-parameter equations and one three-parameter equation were evaluated for goodness of fit of moisture content vs. water activity for 75 sorption isotherms representing fruit, vegetable and meat food products. It was found that the three-parameter Guggenheim-Anderson-de Boer (GAB) equation could represent more than 50% of the food isotherms with great accuracy. An equation having a mean relative deviation modulus of equal to or less than 5 was considered to represent a good fit to the sorption data. In all cases, the GAB equation described the fruit, vegetable and meat isotherms much better than the two parameter equations. The mean relative deviation modulus and parameters for each of the equations are given in this paper.
Discussion:Moisture sorption isotherms equations describes the relationship between water activity (Aw) and the equilibrium moisture content for a food product mathematically. Such an equation will allow one to calculate drying time, packaging and shelf life, the "sogginess" of a product and many other characteristics associated with foods.

Mean Aw range for fruits [modified].
PRODUCTTEMPERATURE
C		Aw Range
apple200.04-0.94
apple400.11-0.97
apple600.25-0.80
apple4.40.09-0.68
apple4.40.20-0.75
avocado250.10-0.80
avocado250.10-0.80
banana250.05-0.80
grapes, seedless250.11-0.92
grapes, seedless250.11-0.93
grapefruit250.05-0.80
peach00.25-0.99
peach200.17-0.98
peach400.17-0.99
pear250.10-0.80
pear250.10-0.80
pineapple250.05-0.80
prune250.23-0.91
prune250.11-0.91
raisin, 22 Brix250.53-0.84
raisin, 17 Brix250.53-0.84
sultanas250.45-0.72

Mean Aw range for vegetables [modified].

PRODUCTTEMPERATURE
C 		Aw Range
Beet, red 25 0.05-0.80
Beet, red 25 0.1-0.80
Raw Sugar Beet Root 20 0.05-0.68
Freeze dried Sugar Beet Room 35 0.02-0.67
Black Root 25 0.05-0.80
Black Root 25 0.10-0.80
Cabbage, unblanched37 0.11-0.77
Cabbage, unblanched 37 0.11-0.77
Celery 25 0.05-0.80
Chive 25 0.05-0.80
Carrot 37 0.06-0.77
Carrot 37 0.06-0.77
Corn 30 0.10-0.91
Lentils 25 0.05-0.80
Horseradish 25 0.05-0.80
Lupins, blue bitter 25 0.42-0.80
Lupins, blue bitter 25 0.35-0.88
Onion, Yellow Globe 30 0.11-0.86
Onions, Yellow globe 30 0.11-0.86
Peas, dried 25 0.25-0.92
Peas, dried 25 0.41-0.92
Peas 10 0.10-0.90
Radish 25 0.05-0.80
Spinach 37 0.12-0.77
Spinach 37 0.12-0.77
Pinto Beans 21 0.65-0.93
Tick Beans25 0.37-0.93
Tick Beans 25 0.43-0.92
White Pea Beans 21.1 0.55-0.85
Soya Beans 25 0.34-0.87
Soya Beans 25 0.20-0.96
Soybeans, Clark 30 0.10-0.88
Soybeans, Clark 30 0.10-0.85

Mean Aw range for meats [modified].

PRODUCTTEMPERATUREAw Range
Bacon, 10% fat250.11-0.84
Bacon, 50% fat250.22-0.93
Bacon, 50% fat250.19-0.94
Beef, raw21.10.11-0.99
Beef, raw21.10.05-0.96
Beef, cooked/minced, 9% fat300.10-0.79
Beef, cooked/minced, 32% fat300.10-0.79
Beef, raw, lean200.17-0.99
Bologna210.10-0.89
Bologna380.12-0.88
Cod, freeze dried250.07-0.90
Chicken250.05-0.80
Chicken250.10-0.80
Pork, cooked4.40.10-0.92
Pork, cooked4.40.20-0.90
Mullet Roe, unsalted250.11-0.80
Mullet Roe, unsalted430.22-0.92
Mullet Roe, salted250.15-0.83
Mullet Roe, salted250.15-0.94
Salmon, freeze dried370.11-0.95

Updated: Thursday, September 6, 2007.

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