Ebook Guide To Canning And Preserving
Food is canned by heating what goes into the container and then sealing the container to keep out air and microbes. It is then reheated after the can jar is sealed. Like cooked food, canned food is subject to changes in appearance and nutritional content. Heating food often changes its color and texture (see Chapter 20). It also destroys some vitamin C. But canning effectively destroys a variety of pathogens, and it deactivates enzymes that might otherwise cause continued deterioration of the food. A modern variation on canning is the sealed plastic or aluminum bag known as the retort pouch. Food sealed in the pouch is heated but for a shorter period than that required for canning. As a result, the pouch method does a better job of preserving flavor, appearance, and heat-sensitive vitamin C. The technique of canning food in glass containers was discovered (depending on your source) either in 1809 or 1810 by Nicholas Appert, a Frenchman who noted that if he sealed food in a container...
If you live at an altitude of 1,000 feet or more, you may need to cook food longer to kill bacteria. At higher altitudes, water boils at a lower temperature, which makes it less effective for killing bacteria. Most cooking and canning temperatures are based on food preparation at sea level. Avoid using your microwave oven for canning. The pressure that builds up inside the jar may cause it to explode.
. . . if rinsing canned beans reduces the sodium content If you rinse canned vegetables, including beans, in a strainer under cool running water, you can reduce their sodium content by 23 to 45 percent. The rest remains. You also rinse away some nutrients, such as some B vitamins, that leach from vegetables into the canning liquid.
Modern processing methods began in the 1800s with canning, giving perishable food a longer shelf life. People finally could eat a variety of fruits and vegetables year-round. During the nineteenth century, pasteurization a process of heating milk or other liquids to kill disease-causing bacteria was developed.
The continuous-flow heat process is a thermal heat-hold-cool process where the foodstuff to be treated is pumped in continuous flow through heat exchanger systems where it is heated to a desired temperature, held at that temperature for a pre-determined time, then cooled to around ambient temperature. After heat treatment, the product is then packaged in an appropriate manner. This process is different from in-container processes, such as canning or retorting, in which the product is firstly packaged and sealed, and then heat treated.
Derived from hydrolysis of cornstarch employed in numerous foods, for example, baby foods, bakery products, toppings, meat products, beverages, condiments, and confections GRAS additive Derived from cornstarch major users of dextrose are confection, wine, and canning industries used to flavor meat products used in production of caramel variety of other uses beverages with cocoa fat used in production of cane sugar and in canning Derived from dried fish or seaweed
How nutritious are canned and frozen vegetables and fruits Most frozen produce is processed without cooking, so most of the micronutrient content is conserved. But canned vegetables and fruits undergo a heating process that destroys much of the vitamin C and B vitamins.8 Also, minerals leach out of canned food into the water, and unless the liquid in the can is used in food preparation, the minerals will be lost. Large amounts of sodium are added during the processing and canning of vegetables. Canned fruit is often conserved in heavily sugared water. A fresh peach has about 70 calories a canned peach, with the added sugar, contains about 180 calories. When available, fruit that is conserved in its own juice is preferable.
As for foods, you should avoid canned, packaged, and other forms of processed foods. Prepare as many of your meals as possible from fresh ingredients. Resort to canning and other forms of safe food storage. When you buy vegetables and fruits, buy organic. Even better, grow your own vegetables and fruits. If that is impossible, buy them from a farmer's market. Be sure to ask about their use of pesticides and herbicides.
Losses during UHT processing are around 27 ,13 but UHT milk stored for 3 months can lose 35 of this vitamin. Average losses as a result of roasting or grilling of meat are 20 , with higher losses (30-60 ) in stewed and boiled meat. Cooking or canning of vegetables results in losses of 20-40 .
As already discussed, all vitamins exhibit a degree of instability, the rate of which is affected by a number of factors. Naturally-occurring vitamins in foods are susceptible to many of these factors during the harvesting, processing and storage of the food and its ingredients. It is particularly important that the effects of processing are taken into consideration when assessing vitamin stability in foods, as the food may have been subjected to a number of adverse factors during processing. The most common factor during processing is the application of heat, which in some cases, such as canning, can be for a relatively long time. Most of the work on the stability of vitamins in fruits and vegetables during blanching and canning was carried out during the 1940s and 1950s. Although there have since been refinements both in processing and analytical techniques, many of the conclusions drawn from this research are still valid.
Consequently, food irradiation is a tool that supplements traditional methods of food preservation it has already found its niche application. The total volume of goods treated is still small, estimated at about 200 000 tonne per annum, one half of which is spices and dry seasonings. Official statistics are unavailable for other methods such as canning, cooling and freezing. As the development in the US clearly demonstrates, the industrial implementation of radiation processing and its acceptance by the consumer come at the time when awareness for such needs has been established and the product is clearly labelled. This means that a slow but steady growth of the amount of irradiated food is to be expected.