SPECIFIC MODIFICATIONS OF CELL-WALL HYDROCOLLOIDS IN A NEW TECHNIQUE FOR PROCESSING HIGH-QUALITY CANNED VEGETABLES

Because of the results of many years of extensive research work on pec tin and pectin enzymes in Hohenheim, the idea that pectin plays a very decisive role in any form of processing of raw plant products due to its function in the unity of the plant tissue gained ground. On the ba sis of this knowledge a solution for the prevention of the enormous di sadvantages of Appert's conventional canning method (namely the excess ive softening of the vegetable tissue and the leaching of nutrients) w as searched for and found, which took into consideration the character istic features of the indigenous pectic enzymes and pectic substances in the vegetable tissue. It was realized therefore that one should not - as in the conventional method - indiscriminately inactivate all enz ymes during the pretreatment step. On the contrary, through a specific time/temperature-controlled pretreatment one must utilize those indig enous enzymes which initiate specific changes or alterations in the pe ctic substances which bear relevance to texture. The so altered pectic substances should (in combination with already available or added cal cium salts) be prevented from excessive degradation during sterilizati on - contrary to the conventional method - so that a firming of the ve getable tissue rather results. The product - although well-done - will be crispy in texture. The amount of brine usually used in the convent ional method is decreased drastically. And because the cans are vacuum -sealed, the brine which conventionally serves as heating medium is re placed by steam during the preheating and sterilization steps. Both th ermal processes take place in the same container. Because of the small amount of fluid there are practically no leaching losses, particularl y since this fluid which practically adheres to the vegetable and rend ers it juicy is eaten together with the vegetable. Through the absence of leaching losses (and perhaps because of the lack of reaction mediu m) the aroma, taste and colour were well maintained. The result was a product with excellent sensory quality.