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Extrusion conditions key to sensory profiles of legume based snacks: Study

By Nathan Gray , 06-Jan-2011

Varying the extrusion conditions of snacks made with lentil flour may help to create more acceptable sensory attributes in new product development, according to a new study.

The study, published in Journal of Sensory Studies, suggests that the flavour, texture and appearance of legume and corn extrusions may be improved by differing extrusion conditions. The authors said that knowing more about the relationship between extrusion conditions and the sensory properties of a product “provides a basis for effective product development.”

The research, led by Dr. A. Lazou from the National Technical University of Athens follows on from a previous study by the same research group published in the Journal of Food Engineering , which investigated the textural and structural properties of corn and legume extrusions.

“Sensory characteristics of corn and corn–lentil extrudates developed in this study could be used by the snack industry to understand the similarities and differences of extruded snacks produced at different extrusion conditions and feed compositions and to select the appropriate ranges of processing conditions to meet consumers’ expectations,” said the researchers.

Protein source

The authors said that grain legumes are an important source of food proteins and dietary fibres, which often represent “a necessary supplement to other protein sources.”

They said that extrusion cooking technology has been used to develop various types of snack foods, mainly from corn meal, rice, wheat flour or potato flour – in many shapes and a variety of textures. However they noted that the application of extrusion to legume flours is a relatively new area.

“Sensory evaluation is important in product development, product improvement and optimization. Extrusion conditions, as well as raw material properties affect the sensory characteristics of products,” said the researchers.

The new study investigated the sensory attribute changes (appearance, flavour, texture and overall acceptance) of corn and corn-lentil extrudates as affected by differing extrusion conditions using a twin screw extruder

Study details

Lazou and colleagues reported the sensory characteristics of the corn and corn–lentil extrudates produced depended both on the process conditions and the raw material characteristics.

The addition of lentil flour resulted in darker products, which were reported to be “not very appealing”.

The overall acceptability of the extrudates generally decreased with the addition of lentil flour, with the exception of the 30 per cent material ratio in addition to an increase of feed moisture content and extrusion temperature, said the authors.

“The correlation of sensory properties showed that crunchiness can be related with appearance attributes of the extrudates and overall acceptability,” said the researchers.

“The hardness of the extrudates was correlated with mealy flavour and negatively correlated with crispness, melting and burnt flavour,” they added.

“Furthermore, all the above characteristics were correlated with the overall acceptability of snacks. This fact means that, the higher the porosity, crunchiness and diameter of the extruded snacks, the more acceptable the products will be.”

Desired attributes

The authors said the quality characteristics of extruded snacks that are critical for consumer acceptance are mainly the sensory characteristics, which “may include crisp and well expanded texture, homogeneous structure, good taste, attractive appearance, colour and aroma.”

“From these findings it is evident that the interaction between process conditions and raw material characteristics plays an important role in the formation of the sensory attributes of extruded snacks,” said Lazou and co workers.

“By manipulating the process parameters and feed composition during extrusion cooking, one can tailor a product of any desired attribute,” they said.

Source: Journal of Sensory Studies
Published online ahead of print, doi: 10.1111/j.1745-459X.2010.00308.x
“Sensory properties and acceptability of corn and lentil extruded puffs”
Authors: A. Lazou, M. Krokida, C. Tzia

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