Stabilized pasta: characteristics and production technologies29 March 2010
This article is devoted to stabilized pasta, with a presentation of the product features and technologies of production.
by Giuseppe Ciccarone
The Italian market for prepared pasta dishes has held a privileged position for thirty years already, in the distribution of a wide variety of fresh pasta products, all of which share the same need: satisfactory means of preservation. This category of products is defined as semi-perishable, and needs a controlled temperature from production plant to consumer, of about +4°C; the Italian legislator allows a tolerance due to possible fluctuations along the distribution chain.
How to extend the shelf life of fresh pasta
Food technologies permit many pasta producers to guarantee an ever and longer shelf life for their food products, obtained through the combined effect of many factors, influenced by techniques and technologies that come into play from the beginning of the production chain: control of the microbiological characteristics of the raw materials; processing technologies that ensure the reduction of contaminants, first among these pasteurization; packaging in modified atmosphere; the use of microfiltered air and control of the humidity and temperature in the processing sites, particularly in the post-pasteurization areas that precede packaging; optimum management of the operations to sanitize the premises and surfaces in contact with the products; and many other aspects. This “alliance of factors” is defined “the hurdle effect”.
“Stabilized” means pasta that can be stored at room temperature. To produce stabilized pasta, the producers must organize and optimize the processes, following parameters of prevention and elimination of well-defined microbiological contaminants, in order to make the pasta an unsuitable terrain for the development of pathogenous and degenerating microorganisms.
Everyone is familiar with and enjoys fresh pasta, but stabilized pasta products are not nearly as well known, as defined from the legislative standpoint and obviously different from the merchandising standpoint.
It is not easy to find them in our grocery stores and supermarkets, often tucked away in a remote corner, sometimes displayed next to the flour, rice and dry pasta. We are talking about pasta that can be stored outside the refrigerator, at room temperature and for this reason – as we have said – defined as “stabilized”.
From the standpoint of Italian legislation, according to Presidential Decree no. 187 of 2001, what differentiates fresh pasta from stabilized pasta are the values of humidity and activity of the water: fresh pasta must have a humidity content of more than 24% and a water activity between 0.92 and 0.97, while stabilized pasta must have a humidity content of more than 20% and a water activity below 0.92%.
Why choose these products
We are not interested here in exploring the reasons for the lack of interest in Italy for pasta products that can be stored for many months at room temperature; we are interested, however, in this brief article, in talking about the methods and production technologies of a type of pasta, which could be an interesting factor of corporate diversification and, for some producers, an opportunity for expansion worth considering. But we have to warn the reader: it is far from simple to produce excellent stabilized pasta, capable, that is, of competing, quality-wise, with fresh pasta.
From the consumer’s standpoint, a definite advantage of this product is the long shelf life and ease of storage: it is possible to reach as much as twelve months of shelf life. This can be particularly important also in consideration of the fact that consumers tend more and more to reduce the frequency of their food purchases, and consequently store as much as possible at home: and why not have good pasta in the pantry, without having to check the expiration date all the time?
The cooking time is also an interesting feature: for products of the same size and with the same ingredients, the cooking time is between that of the fresh product and that of dry pasta.
A microbiological aspect
Although the pasteurization temperature is not able to eliminate spores of Clostridium botulinum, it is known that these do not cause any problems if the product is stored at temperatures below +8°C; if this temperature is exceeded, however, the risk increases and toxins that are extremely dangerous for the human organism may be produced. Most agree that cooking the pasta immediately inactivates them, and in any case in stabilized pasta the reduction of the moisture and water activity (as well as the other integrated factors we have mentioned) inhibits and delays germination of the spores and production of the toxin within limits that guarantee a high degree of food safety. We can add that any deteriorating microorganisms that survive the production process under these conditions of water activity are unable to achieve an intense microbial activity capable of reducing the shelf life of the product.
But just what is the technology used to “stabilize” pasta?
The production process for stabilized pasta is the same as the normal procedure for fresh pasta, with the difference that, in general, pasteurization and drying are more intense, and generally speaking, a second pasteurization stage takes place after packaging. These are the steps in the process:
• preparation of the dough and shaping of the product;
• pasteurization of the product in bulk;
• drying of the product in bulk;
• cooling and packaging;
• second pasteurization of the packaged product;
• cooling to room temperature.
Among the many variations in the technological processes to reduce contamination of the pasta, we would like to stress the use of microfiltered air in the rooms that follow pasteurization of the bulk pasta and precede the packaging process. This makes it possible to perform the second pasteurization after packaging with lesser intensity, thanks to the reduced microbial load of the product due to the presence of fewer contaminants of environmental origin on the surface in contact with the pasta and the air. This process has no benefit from the standpoint of contaminants present on the primary packaging, film and trays.
The second heat treatment made on the packaged product is the one that, from the technological standpoint, most differentiates a stabilized pasta product from a fresh one. In operating practice, many companies perform this second heat treatment also for fresh pasta, either due to the obsolescence of the equipment or the impossibility (or even, in some cases, the inability) of ensuring the best operating conditions of management and control of the critical stages that affect the duration and safety of the products, or more simply, “just to make sure”.
In this connection, it is not superfluous to note that the second pasteurization does not inactivate all microbial forms, in particular certain spores: for this reason a producer cannot and should never speak of “sterilization”.
For the production of stabilized pasta, in determining the process and microbiological parameters, it is important to obtain the services of a competent, qualified person who can be, for example, a good food technologist. Considering that these pasta products should last several months without being refrigerated, it is very important to evaluate carefully all the process parameters that can directly and indirectly affect duration, safety and the quality of the resulting product. Many companies design, build and install systems for fresh and stabilized pasta, as well as prepared dishes, and are able to construct the required installations according to this logic, with the aid of specialized personnel; among the tests that are necessary, the data-trace test is very important to record and display on a graph and table the temperature and time parameters relative to the pasta subject to pasteurization, drying, cooling and second pasteurization. In this way it is possible to estimate the amount of thermal pasteurization treatment necessary for the bulk and packaged pasta and determine the amount of the total microbial reduction, without overlooking the goal of reducing damage to the organoleptic characteristics of the products. With the same heat treatment, the heating curve of the packaged product depends, in addition to the characteristics of the product itself, on the size and shape of the pasta, the quantity and the design and size of the package. Effectively, by changing the size of the package and thus the position of the pasta inside it, it is possible to reach the desired heating temperature at the heart of the package with different timing, thereby causing heat damage to the product and its quality as a whole.
In short, what are the factors that determine the long “shelf-life” of stabilized pasta? The goal of durability and organoleptic quality can be achieved only with careful attention to the many factors involved. Let us list the most essential ones: quality of the raw material (semolina/flour, water, eggs, other characterizing ingredients like powdered spinach, squid ink, etc.) and any fillings (meat, deli meats, cheese, vegetables, nuts, etc.), the construction and technological features of the processing system, the layout of the production plant, the management and control of the production and sanitizing systems in the plant and rooms in which it is installed, definition of the process parameters for each separate step, special recipes for every package size related to the study of the processing parameters, and characteristics of the packaging materials. These latter considerations may escape control if not supported by a real expert in materials: a high oxygen and humidity barrier effect is indispensable to guarantee that all the work is not in vain due to the undesired penetration inside the package of moisture and oxygen during the product’s shelf life. Moisture would tend to facilitate the start of development of possible latent microorganisms and spores; the presence of oxygen in the package would enable aerobic microorganisms in the package to become biologically active.
Attainment of the best organoleptic quality possible, as close as possible to that of the freshly made product, is surely the goal to pursue for high quality stabilized pasta. If on the one hand there can be no doubt that thermal damage connected with the Maillard reaction leads to the formation of brown compounds with alteration of the appearance and flavor of the product, the reduction of certain nutrients and the deterioration of the sensorial characteristics of the pasta, on the other, the use of high temperature treatments makes the glutinous network of the pasta more compact and tenacious: this ensures a better level of cooking with reduced release of starches in the water. Perhaps this is one of the main differences between fresh pasta and pasta subject to intense heat treatments.