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Advisor(s)
Abstract(s)
The quality of dehydrated products is a concern
because, due to their very low moisture content, they tend to
rehydrate quite easily, thus compromising the chemical,
enzymatic or microbial stabilities, as well as the nutritional
and sensorial properties. Having this in mind, this study was
undertaken to evaluate the effects of storage in walnuts, under
certain conditions of temperature, relative humidity and
different types of packaging. The fruit samples used were
from Chile, Portugal, Romania and United States. The storage
of the walnuts lasted for 90 days, and the conditions tested
were: room temperature; a stove at 30 and 50 °C without
control over relative humidity of the air; refrigeration and
freezing. The two types of plastic package tested were low
density polyethylene (LDPE) and linear low density
polyethylene (LLDPE). The water activity was measured by a
hygrometer; moisture content by oven drying until constant
weight and colour with a colorimeter. From the results
obtained it was concluded that the samples from the different
origins are different with respect to moisture content, water
activity and colour, regardless of the storage conditions and
type of package. Furthermore, it was verified that to assure the
good preservation of the walnuts the storage at 50 ºC should
be avoided, since it caused an extensive dehydration of the
product and a high change in colour in comparison to the
unstored samples. Finally, regarding the type of package, it was observed that the use of plastic bags did not really
improve the products characteristic in relation to the unpacked
samples.
Description
Keywords
colour walnut moisture content water activity
Citation
Guiné RPF, Almeida CFF, Correia PMR (2015) Influence of storage conditions and type of package on some properties of walnuts. Millenium, 48, 185-193.
Publisher
Instituto Politécnico de Viseu