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Technology improves tradition
Article taken from "Automazione Industriale", issue 122 - February 2005

Immagine 1
"Misshaping" of the Pandoro during the product cooling stage

Thanks to Automa's Super-Flash, Gamba Automazioni has made a reliable and state-of-the-art supervision system for Panettone (Italian Christmas cakes with sultanas and with/without candied fruit), Pandoro (plain Italian Christmas cakes with icing sugar topping to be added at the last minute), and Colomba (Italian Easter cakes shaped like a dove) produced by Maina S.p.A.

By Elena Bertillo, Automa marketing

What would Christmas be without unbridled consumption of food, festive tables covered with all sorts of goodies: in every Italian home, but more and more throughout the rest of the world, there's one cake which is never missing - Panettone. Nowadays there are all sorts of this cake - traditional, filled or glazed, and in all sizes, too: tall, stubby, small or large - all you have to do is choose the one you like best. But how can you distinguish one Panettone from another? What are the differences? Panettone is a product subject to rules and it can only be called Panettone when it is made using specific ingredients, such as natural leaven, butter, fresh eggs, and so on, mixed together in certain amounts and following a precise procedure (for example, if margarine is used instead of butter, this cake cannot be called Panettone). Notwithstanding these restrictions, there can be different types. The basic difference is between the traditional kind, only made with sourdough, sometimes known as "mother yeast", and the "untraditional" type, where a mixture of sourdough and beer yeast is used. Both are called Panettone but the production process is very different, as are the organoleptic characteristics of the finished product. "The traditional Panettone, produced following the original recipe, is much tastier, highly digestible and, although it does not contain any preservatives, has a long shelf life", explains Massimo Di Gennaro, in charge of production at Maina.

Immagine 2
Traditional Panettone ready to be packaged

Maina was set up 40 years ago in Turin as a small confectionary workshop. In 1969, with the acquisition of a biscuit factory, it transferred to Fossano (Cuneo, Italy) to face the increasing demand for numerous delicacies (sponge cakes, croissants, macaroons, Panettone, etc.). The new facility was inaugurated in 1974, and this is where the company's head office is today. The range of products offered up to that time was limited in order to concentrate on oven-baked cakes for festive occasions (Panettone, Pandoro and Colomba) so as to ensure large production volumes and, at the same time, be able to guarantee their quality. Nowadays Maina produces about 15 million products a year, thanks to round-the-clock operation, seven days a week of the two production lines in the factory, which give out a mouth-watering fragrance of newly-baked cakes all year round (except for the summer period when the plants are stopped for maintenance).
The two production lines are not at all the same: line 1 is set up for preparation of traditional Panettone made only with sourdough, whereas line 2 was built in 1989 to produce Pandoro and filled Panettone, which require the use of a mix of leavens (sourdough and beer yeast).

Immagine 3
Mimic diagram for dosing the water

The working process of the two lines differs greatly - just imagine, it takes about 50 hours to prepare a traditional Panettone, whereas a Pandoro or a filled Panettone "only" takes 35. The production cycle of the festive season oven products is divided into four distinct stages: kneading, leavening, baking and packaging. The first stage is the most delicate one, where the risks of losing the whole production batch are greatest.
On line 1 the product starts its life when an operator takes "the mother" out of a special chamber. Following kneading with water and flour, after a few hours of resting, this gives rise to the sourdough - the essential ingredient for both Panettone and Colomba, as well as for Pandoro. This initial stage is needed to produce a large amount of leaven, part of which is then removed to become "the mother" on the following day. When this fundamental regeneration process, common to both production lines, has been completed, the kneading machine discharges the leaven produced into a mixing carousel, where the various ingredients (water, flour, sugar, butter and eggs) are dosed and mixed together. From here, the mixture first passes into the vats train, consisting of numerous containers, where it rises for twelve hours and triples its volume, and then into a second carousel, where the mixture is completed by adding further flour, water, honey and fruit (candied fruit and sultanas).

Immagine 4
Screen of the supervision system relative to the first carousel of line 1

The second stage then begins. First of all the mixture passes into a hopper, a piece cutter and a roller, which prepare the individual sizes (500, 750 or 1,000 g), positioning them in the "pirottino" - the typical paper surround for holding Panettone. Each single "raw" product is then put into a leavening chamber for 8/10 hours with controlled humidity and temperature. Following this and after any glazing operations, the cake passes into the oven where it is baked for about 1 hour. The product must then be cooled "upside-down", to keep its typical dome shape, at room temperature for about 10 hours. When the fragrance of newly-baked Panettone has spread throughout Maina and the vicinity, the now cold cake is checked to see that the weight and shape parameters provided by "Vision 2000" have been respected. Finally, the cake is packaged.
The Pandoro and filled Panettone produced on line 2 require slightly different processing from the one for traditional Panettone. During the leavening stage, the dough does not need to remain in the vats train. In fact, line 2 only has two mixing carousels, where the beer yeast, milk, eggs, water, flour, butter, etc. are added to the sourdough. In fact, the traditional Pandoro and filled Panettone recipes require the use of beer yeast, which considerably speeds up the rising process.

Immagine 5
Mimic diagram for dosing flour and sugar

The second notable difference between the traditional Panettone and filled Panettone or Pandoro regards the post-baking cooling stage. Whereas the traditional Panettone is cooled down at room temperature, the filled Panettone and Pandoro are put into the High Speed Cooler - a forced cooling machine which lowers the temperature by about 50°C in one minute. This is a particularly important operation for Pandoro, which has to be removed from its aluminium and teflon mould, where the raw mixture is put to give it its classic eight-pointed star shape. This is only possible with a rapid drop in temperature, otherwise the product would be spoilt. On the other hand, the traditional Panettone would not put up with a treatment like that, which would ruin the product, changing its organoleptic characteristics. In any case, following the initial rapid cooling phase, both the Pandoro and the filled Panettone remain at room temperature for about two hours to cool down further before being packaged.

Immagine 6
Mimic diagram of machinery washing

The process for working festive season oven products is very delicate, especially during the dosing and kneading stage, when the large number of parameters (quantities, temperature, weight, etc.) which allow the cakes to be made following the traditional recipe must be kept under strict control. In 2002 this was exactly the reason why Maina decided to entrust modernisation of the two supervision systems (one per line) of this very critical stage to Gamba Automazioni, a Piedmont company specialised in designing and implementing automation systems and in developing software for traceability.
First of all, in 2003, Gamba Automazioni devoted itself to carrying out maintenance on the control centre of line 2 - the most recent one, replacing any components which had become obsolete and making three new supervision applications using SUPER-FLASH, the Automa development system. Having to operate on an existing system, the company needed to adapt to the characteristics of the old plant and therefore the three pieces of supervision software each communicate with a PLC: one monitors the plant (one leavening and two mixing carousels), one manages addition of liquids (water, milk, butter and eggs) and the other controls the feed and consumption of flour and sugar.
Gamba Automazioni had to make a completely new automation system for line 1 and was therefore able to use more innovative design techniques and technologies. With this new supervision system, built in 2004, using a single application it is possible to monitor and manage the plant as a whole, the individual carousels, the vats train, and feeding and dosing, by means of mimic diagrams, of all the raw materials (liquids, flours and sugar). It is therefore possible to display the path and position of each mixture at any time. First of all the "leavening carousel" - made up of some resting vats and 2 kneading machines - is monitored for addition of water and flour, which freshen up the sourdough.

Immagine 7
The Maina production department

The latter is then tipped out into the first carousel, also called "evening kneading centre" because, when Panettone was made by hand, this initial kneading was prepared in the evening, left to rest overnight and then worked again in the morning. The first carousel consists of a vat, where the first ingredients are added, and of two kneading machines where, whilst the next dosing operation is being carried out, everything is mixed at different speeds and times.
All the ingredients (water, flour, eggs, butter, sugar, etc.) come from secondary lines consisting of: storage bins, piping, valves, pumps, litre counters for the liquids and scales with pneumatic conveyors for flour and sugar. Each dosing operation is carried out in a controlled way. Compared to the previous one, the present system is much more accurate, thanks to dosing coefficients which can be parameterised (given by the specific gravity of the product and the litre counter characteristics) and which are periodically verified experimentally and, if necessary, re-calculated using a "calculator" present in the supervision system. Furthermore, for each dose of liquids or flour, "the flight" has been introduced, a parameter which takes into account the amount of extra ingredients which have been put into the mixture. This phenomenon is due to the time which passes between completion of weighing and the actual closing time of the valve of the storage bin containing the ingredient. Calculation of the flight, present in many automatic systems, has been enriched with a self-learning correction procedure, which allows the dosing valves to close early in relation to completion of the weighing operation.

Immagine 8
Maina advert: "Teocoli as an assistant"

From the first carousel the product is tipped out into the vats train where it will rest for 12 hours. This is a highly delicate stage and for this reason two video cameras have been inserted to "visually" control rising and a sonar which indicates the height of the mixture in mm. Thanks to these controls, it is possible to work on the mixture making small changes to the amounts of ingredients added in the following carousel. Another extremely important variable is the temperature. Temperature control is carried out constantly on the four kneading machines (two of the first and two of the second carousels). In fact, because of the addition of some more or less warm ingredients (such as butter, eggs, etc.) and of the processing in the kneading machines, the mixture tends to increase in temperature; it must therefore be lowered, using doses of CO2 also controlled by the system set up by Gamba Automazioni.
From the vats train the mixture passes on to the second carousel, consisting of a dosing bowl and two kneading machines. Finally, the tipper sends the product into the hopper where the pieces are cut.
The supervision system consists of various mimic diagram pages and of numerous control parameter pages which make it very accurate. Thanks to a precise plan for determining anomalies (about 820, each with a description of the actions to be carried out on the PLCs and on the electric circuit diagram), the system is very secure. Another important plus point of the software is its great flexibility, which means that plants with continuous cycle operation, like those at Maina, can be managed efficiently.
The heart of the whole system consists of the recipes. When the "mother" is taken from the cold storage room to be placed in the first "leavening carousel", the recipe to be followed step by step is selected, where all the parameters linked to production of an excellent traditional Panettone are set.

Immagine 9
Maina advert: "Teocoli as a confectioner"

Finally, although a truly fully automatic product tracing system has not yet been implemented, the one at Maina is already able to trace all the information relative to the individual products, in accordance with what is established under the legal obligations of European Regulation 178/2002 regarding company and production cycle traceability, in force since 1st January 2005. In addition to this, thanks to its supervisor functions, the system at Maina already has the possibility of easily and automatically storing the source of the raw materials, the ingredients used and each single dose, together with all the relative information on each finished product.
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