ABSTRACT
H2O/g dried product, g H2O/g dry solids, g rehydrated
product/g dried product, g H2O/g rehydrated product, g
H2O/g fresh product, etc. [3]
Another reason for the commonly encountered discrepan-
cies is soluble solids leaching, which occurs in parallel with
the liquid uptake. Several examples demonstrate the magni-
tude of this issue. The leaching of soluble solids during the
rehydration of dried onions at room and boiling temperatures
was found to be quite significant, and in some cases could
reach more than 70% of the initial dry matter.[4] A higher
solids leaching from air-dried (AD) samples was observed as
compared to explosion-puffed bananas during 20 minutes of
rehydration in boiling water.[5] The medium also has an
impact: more soluble solids were lost during the rehydration
of breakfast cereals in water than in milk (when comparing
their net values, because in milk, solids are also taken up by
the samples). The importance of temperature was illustrated
in another study on cereals: the rate of solids leaching
decreased with temperature for both corn and peanut butter
breakfast cereals.[6] Frosting on puffed breakfast flakes
reduced water uptake, as compared to the unfrosted sam-
ple.[7] On the other hand, the frosted product showed the
highest loss of soluble solids during the soaking process in
semi-skimmed milk. The above-mentioned studies aside, a
great deal of the research into rehydration does not take into
account the leaching of solids to the surrounding solution in
its calculations.
