Canning Of Fruits And Vegetables

Canning of horticultural products like Fruits & vegetables, process of Canning, and the factors that affects Canning process and the effect of microorganisms and chemicals in the canned products.

1. HOR 311 POST HARVEST MANAGEMENT AND VALUE ADDITION OF FRUITS & VEGETABLES CROPS (1+1) PROCESSING OF CANNED PRODUCTS Pesented By… Guhan.C , B.Sc.( Hons ). Agri , Id no : 2018033029 , JKKMCAS , Erode , TN .

2. CANNING Process of sealing food stuffs hermetically(airtight) in containers and sterilizing them by heat for long storage. FATHER OF CANNING - Appertizing In 1804, Appert in France invented Canning. Principle: Destruction of spoilage organisms within the sealed container by means of heat.

3. General Process Of Canning… Selection of fruits/vegetables Grading Washing Peeling Cutting Blanching Cooling Filling and Syruping (or) Brining Exhausting Sealing Processing Cooling Storage

4. Selection Fresh and free from dirt. Fruits should be ripe, but firm and uniformly mature. Over ripe fruits should be rejected. Unripe fruits should also be rejected. Vegetables should be tender except tomatoes. Tomatoes should be firm, fully ripe and deep red in colour . Free from blemishes, insect damage or mechanical injury.

5. Grading Graded according to size and colour to obtain uniform quality. D one by hand or by machines such as screw grader and roller grader. Washing To remove the dirt, dust etc., by water. Root crops - washed - soaking in water - 25 to 50 ppm chlorine. Others washing may be done by spray washing, steam washing, etc. Washing in running water is preferable .

6. Peeling Peeling – removal of outer layer . Hand peeling - F ruits of irregular shape. e.g. mango, papaya. Steam peeling - Potatoes and tomatoes are peeled by steam. Mechanical peeling - Apples, peaches, pineapples, for vegetable like carrot, turnips and potatoes. Lye peeling- P eaches, apricots, sweet oranges & vegetables like carrots and sweet potatoes are D ipping in 1 to 2% boiling lye solution( NaOH ) for 30 sec to 2 min. Then alkali is removed by running water or by dipping in 0.5% citric acid solution. Flame peeling - G arlic and onion which have a papery outer covering. The skin is burnt off .

7. Cutting & Blanching Cutting Fruits and vegetables are cut into uniform pieces for canning. Blanching E xposing f&v to hot or boiling water as a pretreatment before drying. Blanching also known as scalding or precooking. Fruits are not blanched generally. V egetables are blanched in boiling water or steam for 2 - 5 min followed by cooking.

8. Cooling Cooling after blanching, the vegetables are dipped in cold water for keeping them in good condition. Filling B efore filling cans are washed and sterilized. In developing countries - done by jet of steam . In developed countries - large scale filling machines automatically do this sterilization and filling of syrup or brine with fruits or vegetables. India – Hand filling is common. Cooling & Filling

9. Syrupping A solution of sugar in water is called as syrup. Sucrose syrup is used in canning. Syrup is added to improve the flavour and it is serving as heat transfer medium. Syruping is done only for fruits . 20 to 55°Brix concentration is used in syrup. Strained hot syrup is poured on the fruit pieces. The syrup should be filled at about 79 to 82°C by leaving a head space of 0.3 to 0.5 cm. Sometimes citric acid and ascorbic acid are also mixed with syrup to improve flavour , shelflife & to enrich.

10. Brining A solution of salt in water is called brine. Only vegetables are brined. Common salt, free from iron should be used. Hot brine of 1 to 3% concentration is used for covering. Vegetables are placed in the can & filled with brine at 79 - 82°C , leaving head space of 0.3 to 0.5 cm.

11. Exhausting T he process of removal of air from cans is known as exhausting. This is done after lidding or clinching . Advantage Minimizes discoloration. R etention of Vitamin-C. Reduces chemical reaction. Prevents excessive pressure.

12. Sealing & Processing Sealing Immediately after exhausting the cans are sealed air tight by means of a sealer. T emperature should not fall below 74°C. Processing Heating & cooling of canned foods to inactivate bacteria . Bacterial spores are destroyed at pH 3.0 (fruits) than at pH 5.0 to 6.0 (vegetables except tomato). Bacterial spores do not grow below pH 4.5 .

13. Cooling After processing the cans are cooled to about 39°C to stop cooking process and to prevent stack-burning. Cooling is done by, dipping or immersing the hot cans in tanks containing cold water. Exposing the cans to air. Storage After labeling, they should be packed in strong wooden cases or corrugated card board . Stored in cool and dry place.

14. Containers for packing T in and glass containers are used T in containers are mostly preferred . The inside of the can is to be coated with some material (lacquer), which prevents corrosion and discolouration but does not affect the flavour . This process is known as “ Lacquering ”. Lacqer Types… Acid-resistant : C ans coated with it are called R- enamel or A.R. Cans meant for acid fruits . Sulphur -resistant : C ans coated with it are called C- enamel or S-R-meant for non acid foods.

15. Causes of spoilage By 2 reasons… Physical and chemical changes Microorganisms . 1. Physical and chemical changes Swell : Can become bulged . Bulge is due to positive internal pressure of gases. Under-exhausting : Cans suffer severe strain during heat processing due to the large internal pressure of the gas present in it. Paneling : T he body is pushed inward due to the high vacuum inside. Rust : Rust of the cans should be thoroughly examined. Foreign flavour : Under unhygienic conditions products develop foreign or off- flavours .

16. Microbial spoilage Mesophilic organisms Spoilage by mesophilic organisms such as some species of Clostridium bacillus , yeast and fungi is also indicative of under processing. Thermophilic bacteria C ans are stored without adequate cooling , the contents remain at a temperature favourable for incubation with the result that bacteria multiply and spoil the product . Clostridium Thermoplilic