PRODUCTION OF DICED TOMATOES WITH SEMI-CONCENTRATED TOMATO JUICE
|The tomatoes undergo the same technological process as peeled tomatoes up to the peeling stage, after which the product is cut into cubes using a dicer, dejuiced by using a vibrating screen, graded manually or electronically (like the peeled tomatoes). It is then sent for the final packaging with juice. Yields are almost the same for peeled tomatoes or slightly higher.The packaging can be in cans or in bags in box. In case of can the process is similar to the one of whole peeled tomato. In the case of bags in box there is a previous mixing of hot juice with diced tomatoes.For mixing usually three tanks are required to ensure continuous processing (one is always on loading phase, one is always full for product stabilisation, and one is always on discharge phase for aseptic sterilization). All the diced product is mixed with the tomato juice with a suitable holding time to allow maximum heat exchange and optimal diced/juice osmosis. The tanks agitators are designed for mixing without damaging the cubes.
Some countries require and/or allow 900 ppm of calcium chlorine (CaCl) to be added to the mixture, though this must always be indicated on the label. Adding this substance causes the diced product to harden, thereby making it firmer and consequently easier to pump.
Having carried out the preparation stage inside the tank, dices and juice are sent to the aseptic sterilizing-cooling system via large diameter tubes, special valves and pumps which do not damage the dices. Inside the tubular sterilizer, the product is gradually sterilized up to a temperature of 115°C (depending on the product’s pH value), kept at this temperature for at least 8 minutes and then quickly cooled to about 30 – 35°C in a tubular exchanger, using cold and/or refrigerated water. The aseptic diced product can now be filled inside special 200 or 1000 litre bags, via a 2” opening instead of the 1” one used for tomato concentrate. It goes without saying that the aseptic filler must be especially equipped with a 2” opening.
The following are the basic processing steps for the production of good quality crushed tomatoes:
• suitable tomatoes are conveyed by flotation to the manual sorting table;
• washing and manual sorting on roller belt by personnel;
• skin elimination by means of specific skin-removing devices;
• manual sorting of whole peeled tomatoes on inspection belt by personnel
• dicing of whole peeled tomatoes by continuous dicer;
• draining (de-juicing) of diced tomatoes through a vibrating screen unit;
• manual or automatic sorting of dices;
• recovery of wastes from optical and manual sortings, from skin removers and from the peeler by a screw-type chopping pump and delivery to a heat exchanger;
• heating of all recovered wastes up to 90°C in a tubular heat exchanger;
• refining of hot wastes with the pulper-finisher;
• concentration of the juice to 8 / 11°Brix;
• blending of diced tomatoes with semi-concentrated juice as indicated by customer.
ASEPTIC FILLING INTO BAGS
Normally in Europe aseptically packed chopped tomatoes are made from whole peeled tomatoes chopped into 17 x 17 x 12 mm dices while the North American market prefers larger dices (up to 1” cut); the final composition is obtained from an average of 60% – 70% dices and 40% – 30% sauce at 8/11°Brix. Filling process shall respect the following steps:
• sterilization at a temperature of 106°C;
• holding time: approx. 10 minutes at 106°C;
• cooling at a temperature of 40°C;
• suggested equipment: tube in tube heat exchanger with a product passing section of at least 60 mm;
• aseptic filling by twin-head filler in order to avoid product re-cycling which would damage the integrity of the tomato dices.
HOT FILLING INTO 3 & 5 KG CANS
In Italy a common type of container for chopped tomatoes are 3 and 5 kg cans, with a net weight respectively of 2500 gr. and 4200 gr. (net weight = dices + semi concentrated sauce without the container). These containers are especially produced for caterers such as pizzerias, restaurants, schools etc. and are not normally intended for family use.
Chopped tomatoes produced for cans is made from whole peeled tomatoes chopped into 14 x 14 x 12 mm pieces, while the North American market prefers larger dices (up to 1” cut); the final product is obtained from 65% dices and 35% sauce at 7/8°Brix.
The filling process shall respect the following steps:
• volumetric dosing of dices into cans;
• topping of cans with hot tomato sauce at 90°C ;
• Seaming of full cans with adequate cover;
• sterilisation of full cans in a belt type continuous sterilizer at about 96 – 98°C for approx. 40 – 60 minutes (the sterilisation time depends on the quality of product and containers; these data are only approximate and do not give any warranty of any kind; the sterilisation time shall be sufficient to obtain a F100 sterilisation value higher than 20). Rotating cans sterilizer and/or retorts may also be used;
• cooling of full cans by means of cold water sprays in order to reach a product temperature measured in the centre of the can (can centre temperature) of about 40°C;
• palletization of full cans on wooden pallets to be stored in a warehouse for approx. 20 days in order to carry out quality controls prior to final packaging and delivery.
HOT FILLING INTO 0.5 KG CANS
There are several kinds of chopped tomatoes produced for family-sized packaging: from 6 x 6 x 6 mm dices up to 20 x 16 x 14 mm dices, with different final solids mix from 4.5 to 10°Brix (measured on the shaken/milled product). Aromatic herbs and various spices may also be added to the finished product according to specific brand recipes.
The packaging and sterilisation phases are the same as above.