Pasta Manufacture
– From Plant Breeding to the Cooking Pot
A Case-Study in
Food Waste Reduction (Minimization)
A One-Day Seminar,
Sunday, September 9, 2001
Industry knows “how” to manufacture pasta. It is a knowledge that has been developed over the years by trial-and-error and has been passed down from one generation to the next via an apprenticeship process. Often, however, industry does not know “why” things happen the way that they do. Without this knowledge, one can only achieve an efficiency that a trial-and-error approach and intuition allows. Only by understanding and explaining scientifically the “why” will one have capacity that allows one to improve the “how”. The goal of the “Waste Reduction in Pasta Manufacture” Project was the accumulation of the knowledge necessary to explain “why” pasta might crack during manufacture and, thereby, identify new ways in which to perform the manufacturing.
Under the terms of the agreement with the NSW Government’s Waste
Planning and Management fund, this project was undertaken at the Vetta plant,
Green’s General Foods, in Leeton, with an understanding that the generic
results of the investigation must be made public at the end of the project. In
part, the purpose of the One-Day Seminar is to fulfil the latter undertaking.
Because of the importance of durum wheat to the Australian economy, it also
represents an opportunity to discuss the full spectrum of issues connected with
the production of pasta.
In order to focus on the drying of the pasta and the associated
“checking” (cracking and crazing) that can occur, it is first necessary to have
a basic understanding of the phenomenology of pasta manufacture from plant
breeding through to the cooking pot. This is the motivation behind the way in
which the One-Day Seminar has been organized.
The Seminar will commence with a welcome by the organizations funding
the Project and the One-Day Seminar. This will be followed by presentations
related to NSW Government’s initiatives in waste management and reduction in
the manufacture of foods. A representative of the NSW Government’s Waste
Planning and Management Fund will discuss that organizations aims and goals
from a general, as well as a food manufacturing, perspective. Next, the
background to the “Waste Reduction in Pasta Manufacture” Project will be
outlined, especially in terms of the waste reduction challenge that this poses
and the complexity of the steps involved in the manufacture of pasta. The final
talk, before morning tea, will be presented by a representative of the Cleaner
Production Unit of the NSW Environmental Protection Agency. It will focus on
the challenges for food manufacture.
In the session after morning tea, the focus will be a review of the
overall process from plant breeding through to the cooking pot. The first talk
will focus on the plant breeding, seed selection, growing and harvesting of the
durum wheat. The quality of the final pasta depends as crucially on the quality
with which these steps are performed as any other of the steps in the path from
plant breeding to the cooking pot. The next talk will discuss the milling of
the pasta and, in particular, examine the quality that must be respected during
the milling in order to meet the specifications required for the subsequent
manufacturing.
The final talk in this session will discuss the mixing, extrusion and
drying of the pasta from an industrial perspective. Among other things, it will
stress the role and importance of each of these steps in guaranteeing the
quality of the product as it is packed and when it goes into the cooking pot.
In the session after lunch, the focus will be a review of some of the
key scientific aspects connected with the manufacture of pasta as they relate
to the quality of the product that comes from the cooking pot (assuming that it
is cooked correctly), the physical and chemical changes that occur to the pasta
during its drying. The first talk will discuss the durum proteins in terms of
both the role that they play in giving pasta its strength and shape integrity
during manufacture and its al dente bite after (correct) cooking. The
next talk will examine the durum starches in terms of why high quality pasta is
made with durum semolina, and not durum flour, and the role that they play,
along with the proteins, in giving traditional pasta it slow carbohydrate
release (i.e. glycaemic index). The third talk will address the
physico-chemical basis of the drying of pasta. It will initially establish, on
the basis of published experimental evidence, that the drying of pasta is a “porosity-surface
tension” phenomenon. This conclusion will be utilized to show how the
various stages in the drying of pasta correspond to the surface removal of
moisture, saturated drying, two phase moisture and vapour drying and vapour
drying. The validation of this model against published pasta elasticity data
will be briefly mentioned.
In the final session of the Seminar, the generic results of the Project
are examined. The issues that will be discussed by the various people involved
with the project include
(i)
the measurement (on a high temperature halogen dryer) and
interpretation of weight-loss curves of the pasta at the different stages of
the drying,
(ii)
the use of rehydration to reduce the stress accumulated in the earlier
drying of the pasta, and, thereby, the likelihood of “checking”, and
(iii)
the relationship between the extrusion and the drying including the
effect of the different geometries.