Canning

Canning | Food Prosessing | Canning - how to canning, for canning, canning jars, canning food - is a method of preserving food by first sealing it in air-tight jars, cans or pouches, and then heating it to a temperature that destroys contaminating microorganisms that can either be of health or spoilage concern because of the danger posed by several spore-forming thermo-resistant microorganisms, such as Clostridium botulinum.Spores of C.Botulinum(in a concentration of 104/ml)can resist boiling at 100°C(212°F)for more than 300 minutes; however, as temperature increases the times decrease exponentially, so at 121°C(250°F)for the same concentration just 2.8minutes are required.

From a public safety point of view,foods with low acidity(i.e., pH 4.3)need sterilization by canning under conditions of both high temperature(116-130°C)and pressure. Foods that must be pressure canned include most vegetables, meats, seafood,poultry,and dairy products. The only foods that may be safely canned in a boiling water bath (without high pressure) are highly acidic foods with a pH below 4.6,such as fruits, pickled vegetables, or other foods to which acid has been added.

Cans / Tins

During the early Civil Wars, the notable French newspaper Le Monde, prompted by the government, offered a hefty cash award of 12,000 Francs to any inventor who could come up with a cheap and effective method of preserving large amounts of food. The massive armies of the period required regular supplies of quality food, and so preservation became a necessity. In 1809, the French confectioner Nicolas François Appert observed that food cooked inside a jar did not spoil unless the seals leak, thus developed a method of sealing food inside glass jars. The reason why food did not spoil was unknown at the time, since it would take another 50 years before Louis Pasteur would confirm the existence of microbes. However, glass containers presented many challenges for transportation.

Glass jars were replaced with cylindrical tin or wrought-iron canisters (later shortened to "cans") following the work of Peter Durand (1810), which were both cheaper and quicker to make and much more resilient than fragile glass jars. Tin-openers were not to be invented for another 30 years—at first, soldiers had to cut the cans open with bayonets or smash them open with rocks. The French Army began experimenting with issuing tinned foods to its soldiers, but the slow process of tinning foods and the even slower development and transport stages prevented the army from shipping large amounts around the French Empire, and the war ended before the process could be perfected. Unfortunately for Appert, the factory which he had built with his prize money was burned down in 1814 by Allied soldiers invading France. Following the end of the Napoleonic Wars, the canning process was gradually put into practice in other European countries and in the United States. Based on Appert's methods of food preservation, Peter Durand patented a process in the United Kingdom in 1810, developing a process of packaging food in sealed airtight wrought-iron cans. Initially, the canning process was slow and labor-intensive, as each can had to be hand-made and took up to six hours to cook properly, making tinned food too expensive for ordinary people to buy. In 1824 meats and stews produced by the Appert method were carried by Sir William Edward Parry in his voyage to find a northwestern passage to India. Throughout the mid-nineteenth century, tinned food became a status symbol amongst middle-class households in Europe, becoming something of a frivolous novelty. Early methods of manufacture employed poisonous lead solder for sealing the tins, which had disastrous consequences for the 1845 Franklin expedition to the Arctic Ocean.

Glass jars

Increasing mechanization of the canning process, coupled with a huge increase in urban populations across Europe, resulted in a rising demand for tinned food. A number of inventions and improvements followed, and by the 1860s, the time to cook food in sealed cans had been reduced from around six hours to only 30 minutes. Canned food also began to spread beyond Europe-ThomasKensett established the first American canning factory in New York City in 1812, using improved tin-plated wrought-iron cans for preserving oysters, meats, fruits and vegetables. Demand for tinned food greatly increased during wars. Large-scale wars in the nineteenth century, such as the Crimean War, American Civil War, and Franco-Prussian War introduced increasing numbers of working-class men to tinned food, and allowed canning companies to expand their businesses to meet military demands for non-perishable food, allowing companies to manufacture in bulk and sell to wider civilian markets after wars ended. Urban populations in Victorian era Britain demanded ever-increasing quantities of cheap, varied, good-quality food that they could keep on the shelves at home without having to go to the shops every day for fresh produce. In response, companies such as Nestlé, Heinz, and others emerged to provide shops with good-quality tinned food for sale to ordinary working class city-dwellers. The late nineteenth century saw the range of tinned food available to urban populations greatly increase, as rival canning companies competed with each other using novel foodstuffs, highly decorated printed labels, and lower prices.

Demand for tinned food skyrocketed during World War I, as military commanders sought vast quantities of cheap, high-calorie food to feed their millions of soldiers; food which could be transported safely, would survive trench conditions, and which would not spoil in between the factory and the front lines. Throughout the war soldiers generally subsisted on very low-quality tinned foodstuffs, such as the British "Bully Beef" , pork and beans and Maconochies Irish Stew, but by 1916 widespread boredom with cheap tinned food amongst soldiers resulted in militarily purchasing better-quality food, in order to improve low morale, and the first complete meals in a tin began to appear. In 1917 the French Army began issuing tinned French cuisine, such as coq au vin, whilst the Italian Army experimented with tinned ravioli and spaghetti bolognese. Shortages of tinned food in the British Army in 1917 led to the government issuing cigarettes and even amphetamines to soldiers to suppress their appetites. After the war, companies that had supplied tinned food to national militarily improved the quality of their goods for sale on the civilian market.

Laminate-vacuum-pouches

Today, tin-coated steel is the material most commonly used.Laminate vacuum pouches are also now used for canning,such as those found in anMRE.

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The Trapezoidal Integration Method for Calculating Fo Values in Fishery Products Canning

A mathematical method in which the time-temperature data are used to measure changes I in lethality during heating and cooling. By using standard time intervals the lethal value: is computed in stages and the cumulative L value for the process is found without the need for graphical representation of the heating and cooling curves.

The Fo value for the process is calculated by summing all the L values and multiplying this value by the standard time interval between readings.

The trapezoidal method also allows simple calculation of the contribution to total process lethality of the heating and cooling portions of the process.

In Table 2 are shown L values and in Table 3 is shown a worked example in which temperature was recorded at 5 minute intervals for a process of 60 minutes at 121.1 °C.

To calculate Fo for the process: Summing the L values gives 2.925 which when multiplied by 5 (the time interval between readings) gives an Fo value of 14.6 min.

To calculate Fo for the heating phase: The sum of L values at time 25 and 60 min (0 and 0.776) is divided by 2 and this value (0.388) is added to the sum of L values from time 30 to 55 min. This gives 1.730 which when multiplied by 5 yields on Fo of 8.6 min for the process lethality at the stage when the steam was turned off.

The Improved General Method which relies on a temperature-time plot. for the entire process is the most accurate of all methods for calculating Fo value and for this reason is frequently quoted as the "reference method". Like the Trapezoidal Method there are no assumptions made regarding product heating and cooling characteristics, however the benefits of accuracy have to be balanced against the lack of versatility. Data from one set of trials cannot easily be used to calculate Fo values when product temperature and/or retort temperature are (is) altered. This means that once process conditions are altered new temperature-time data must be collected under the new experimental conditions.

Table 2. Values of L for temperature ranging 
from 90 ºC to 130.9 ºC in 0.1 ºC intervals

oC	0.0	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
90	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001
91	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001
92	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.002
93	0.002	0.002	0.002	0.002	0.002	0.002	0.002	0.002	0.002	0.002
94	0.002	0.002	0.002	0.002	0.002	0.002	0.002	0.002	0.002	0.002
95	0.002	0.003	0.003	0.003	0.003	0.003	0.003	0.003	0.003	0.003
96	0.003	0.003	0.003	0.003	0.003	0.003	0.004	0.004	0.004	0.004
97	0.004	0.004	0.004	0.004	0.004	0.004	0.004	0.005	0.005	0.005
98	.005	0.005	0.005	.005	0.005	0.005	0.006	0.006	0.006	0.006
99	0.006	0.006	0.006	0.007	0.007	0.007	0.007	0.007	0.007	0.008
100	0.008	0.008	0.008	0.008	0.009	0.009	0.009	0.009	0.009	0.010
101	0.010	0.010	0.010	0.010	0.011	0.011	0.011	0.011	0.012	0.012
102	0.012	0.013	0.013	0.013	0.013	0.014	0.014	0.014	0.015	0.015
103	0.015	0.016	0.016	0.017	0.017	0.017	0.018	0.018	0.019	0.019
104	0.019	0.020	0.020	0.021	0.021	0.022	0.022	0.023	0.023	0.024
105	0.025	0.025	0.026	0.026	0.027	0.028	0.028	0.029	0.030	0.030
106	0.031	0.032	0.032	0.033	0.034	0.035	0.035	0.036	0.037	0.038
107	0.039	0.040	0.041	0.042	0.043	0.044	0.045	0.046	0.047	0.048
108	0.049	0.050	0.051	0.052	0.054	0.055	0.056	0.058	0.059	0.060
109	0.062	0.063	0.065	0.066	0.068	0.069	0.071	0.072	0.074	0.076
110	0.078	0.079	0.081	0.083	0.085	0.087	0.089	0.091	0.093	0.095
111	0.098	0.100	0.102	0.105	0.107	0.110	0.112	0.115	0.117	0.120
112	0.123	0.126	0.129	0.132	0.135	0.138	0.141	0.145	0.148	0.151
113	0.155	0.158	0.162	0.166	0.170	0.174	0.178	0.182	0.186	0.191
114	0.195	0.200	0.204	0.209	0.214	0.219	0.224	0.229	0.234	0.240
115	0.245	0.251	0.257	0.263	0.269	0.275	0.282	0.288	0.295	0.302
116	0.309	0.316	0.324	0.331	0.339	0.347	0.355	0.363	0.372	0.380
117	0.389	0.398	0.407	0.417	0.427	0.437	0.447	0.457	0.468	0.479
118	0.490	0.501	0.513	0.525	0.537	0.550	0.562	0.575	0.589	0.603
119	0.617	0.631	0.646	0.661	0.676	0.692	0.708	0.724	0.741	0.759
120	0.776	0.794	0.813	0.832	0.851	0.871	0.891	0.912	0.933	0.955
121	0.977	1.000	1.023	1.047	1.072	1.096	1.122	1.148	1.175	1.202
122	1.230	1.259	1.288	1.318	1.349	1.380	1.413	1.445	1.479	1.514
123	1.549	1.585	1.622	1.660	1.698	1.738	1.778	1.820	1.862	1.905
124	1.950	1.995	2.042	2.089	2.138	2.188	2.239	2.291	2.344	2.399
125	2.455	2.512	2.570	2.630	2.692	2.754	2.818	2.884	2.951	3.020
126	3.090	3.162	3.236	3.311	3.388	3.467	3.548	3.631	3.715	3.802
127	3.890	3.981	4.074	4.169	4.266	4.365	4.467	4.571	4.677	4.786
128	4.898	5.012	5.129	5.248	5.370	5.495	5.623	5.754	5.888	6.026
129	6.166	6.310	6.457	6.607	6.761	6.918	7.079	7.244	7.413	7.586
130	7.762	7.943	8.128	8.318	8.511	8.710	8.913	9.120	9.333	9.550

Note:

z = 10 ºC
T = product temperature

Table 3. Trapezoidal method for integration of 

lethal rate data to calculate Fo value

Time (min)	Temperatur (oC)	L	L/t	Fo (min)
0	24	0
5	24.5	0
10	34	0
15	54	0
20	72.5	0
25	87	0
30	98	0.005
35	105	0.025
40	110.5	0.087
45	114.5	0.219
50	117	0.389
55	119	0.617
60	120	0.776	1.730	8.6
* STEAM OFF
65	120	0.776
70	106	0.031
75	88	0	2.925	14.6

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Calculating Fo Values in Fishery Products Canning: The improved general method

A plot of temperature versus time is made on specially constructed lethal rate paper which has on its left-hand vertical axis product temperature (on a log scale) while on the other vertical axis is drawn lethal rate (on a linear scale). Thus for each temperature can be shown the corresponding lethal rate. Time is plotted along the horizontal axis, using a convenient scale.

The area under the graph which represents the product of exposure time at all lethal rates throughout the process, is then divided by the area equivalent to that of an Fo value of unity. This yields the total sterilising effect, or the Fo value, for the process. In Figure 3 is shown a hypothetical heat penetration curve for a semi-solid product processed for 40 min at 120 ºC.

Figure 3. Heat penetration lethal rate curve

The temperature profile shown is that of the slowest heating point. By counting squares or using a planimeter the area under the graph is found to be 71 cm², while the area corresponding to one unit of lethality (Fo = 1) is 4 cm². Therefore the total process lethality can be calculated,

 
This means the total sterilising effect of the process is equivalent to 17.5 minutes at 121.1 ºC, assuming instantaneous heating and cooling. We have now expressed the severity of sterilisation, as experienced at the slowest heating point of the can.

In the worked example, the retort was not operating at the reference temperature (121.1 ºC) nor did the product reach retort temperature. It is important not to confuse the specification for the process (40 min/120 ºC) with Fo for the process. A process specification alone indicates little about the total process lethality. It would be possible to have a process specification of 60 min at 121.1 ºC and Fo values of, say, 6.2 min and 11.5 min for 450-g and 225-g cans respectively, the different process severity in this case reflecting can size. Similar mode of heating (convection/conduction), pack weight and fill temperature can all affect the Fo value even though retorting conditions may be constant.

To Summarize:

• The improved general method takes account of the entire heating and cooling effects including any changes in heat penetration rates caused by product gelation or liquefaction.
• The thermal characteristics of the product need not be known. While this makes Fo calculation simple it limits the versatility of the technique .
• Theoretically the thermal centre of a conduction heating can is at the geometric centre, while that for a convection heating product is slightly below this on the vertical axis. It is important to locate thermocouple tips at the thermal centre for solid packs heating by conduction but less so for convection heating, as the rapid heat transfer caused by convection currents prevents any significant heating lags.

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The Principles of Canning for Fishery Products: Calculating Fo Values

Thermocouple probe

To be sure of commercial sterility the Fo value at the SHP, the thermal centre of the container, must be sufficient to kill all Clostridium botulinum and reduce survival probabilities for other more heat resistant bacteria to an acceptable level. It is assumed that bacterial spores will randomly contaminate the fish and that therefore they may be located at the SHP. Although a pessimistic approach, this caters for the ``worst case`` scenario on which product safety must be based.

The measure Fo value heat penetration studies are conducted for representative packs of the canned fish filled to the maximum fill weight likely to be encountered. These cans are then fitted with thermocouple probes which must be located so as to measure the temperature at the SHP. (As can-to-can variation in the rate of heat penetration can be significant, it is recommended that at least twelve replicates are tested before data from the slowest heating of all the test cans are used to compute the Fo value for the process).The thermocouples are connected to digital or graphical recorders, some of which indicate the product temperature during the thermal process, while others can be purchased which automatically compute Fo value. Where automatic computation is not possible, the temperature-time data can be used in a number of ways to calculate Fo value.

Figure 2. Thermal death time curve passing through 1 min at 121.1 ºC

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The Principles of Canning for Fishery Products: Lethality of Heat During Heating and Cooling

Clostridium botulinum

Although by convention the sterilising effect of a process is expressed in standard units of minutes at 121.1 ºC (the symbol used is Fo), the product inside a can does not instantaneously reach processing temperature and in some cases of conduction heating, the temperature at the thermal centre of the can never reaches that of the heating medium (which need not be at 121.1 ºC).

This paradox is resolved by making use of a relationship which shows that the rate of change in the thermal destruction of bacteria (i.e. the rate of change in their D values) is logarithmic around temperatures commonly used in heat sterilisation. This means that the lethal rate of destruction at any temperature can be related to that at a reference temperature. This relationship is graphically represented .in Figure 2  which shows a thermal death time curve passing through 1 min at 121.1 ºC. This "phantom" curve shows that relative to the lethal rate of unity at 121.1°C the lethal rates at 91.1, 101.1, 111.1, 131.1, 141.1 and 151.1 ºC are 0.001, 0.01, 0.1, 10, 100 and 1 000, respectively.

The sterilising effect of a thermal process (the process Fo value) can therefore be computed by integrating the combined lethal effect of exposure at all time/temperature combinations throughout the process. This means that a process that delivers an Fo value of 2.8 min (the so called 12D process for Clostridium botulinum) is equivalent in . sterilising effect to heating the contents of the can to 121.1 ºC instantly, holding it at that temperature for 2.8 min, and then cooling it instantly. Similarly, a process for solid style canned tuna packed in 84 x 46.5 mm cans may have a target Fo value of 10 min, which can be achieved by processing for 74 min at 116 ºC or 50 min at 121.1 ºC. With each process, however, the sterilising effect is the same as, and equivalent to, holding the can of tuna at 121.1 ºC for 10 min under conditions of instantaneous heating and cooling.

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The Principles of Canning for Fishery Products: Bacterial Spores Heat Resistance

It is desirable that the test organism in comparative thermal death time determinations be one which grows readily on the ordinary culture medium, with the production of an abundant yield of spores in a minimum time.

It should, furthermore, be an organism which has a characteristic type of growth, or should possess some readily determinable which will serve to differentiate it from contaminants likely to be encountered.

The heat resistance of bacterial spores is specified by the time required to kill 90 per cent of the population at constant temperature; this enables a comparison of heat resistance of spores of many different bacteria. For most spores of importance in canned food spoilage their heat resistance is measured at 121.1 ºC (250 ºF), a common retorting temperature, and is expressed as the D value. A typical plot of the number of survivors against heating time is shown in Figure 1. It can be seen that the time to reduce the population from 1 000 000 to 100 000 is the same as that required to reduce it from 100 to 10. That is, the D value is constant for specific bacterial spores when they are subjected to heat at constant temperature. In Table 1 are summarised the D values of bacterial spores important in canned foods.

Destruction of all spores of Clostridium botulinum is the minimum safety requirement , when thermally processing low-acid canned foods. Canners aim to reduce the probability of one spore surviving the thermal process to such a low level that, for all practical purposes, the contents of the container pose no health risk due to survival of Clostridium botulinum (spores). Experience has shown that a process equivalent in sterilising effect to twelve decimal reductions of the population of Clostridium botulinum is sufficient to protect consumer safety. Such a process is referred to as a "12 D" process and it is equivalent to holding the contents of the container at 121.1 ºC for 2.8 min (12 D= 12 x 0.23 = 2.8 min). A process as severe as this will satisfy requirements (under conditions of good manufacturing practice); however, it will be insufficient to reduce to a commercially acceptable level, the probability of survival for the extremely heat resistant spores (with D values of 2.0 to 5.0 min) of non-pathogenic bacteria. This is why canned fish manufacturers select a thermal process which goes beyond the safety requirements of destruction of Clostridium botulinum.

Fig.1. Survivor curve for bacterial destruction at constant temperature

Although the probability of survival for spores of non-pathogenic heat resistant bacteria may be several thousand times that for Clostridium botulinum spores, their presence is of no great concern to canners for two reasons:

1. Should they lead to spoilage, there is no associated health risk
2. They only grow at temperatures above 40 ºC (i.e., they are thermophilic) and their optimum growth temperature is around 55 ºC, which is above that in most warehouses ) and retail outlets

Table 1. Decimal reduction times (D-values) of bacteria

important in low acid canned foods

Organism	D value (min. at 121.1 ºC)
B. stearothermophilus	4.0 - 5.0
C. thermosaccharlyticum	3.0 - 4.0
D. nigrificans *	2.0 - 3.0
C. botulinum (A & B)	0.1 - 0.23
C. sporogenes (P.A. 3679)	0.1 - 1.5
B. coagulans	0.01 - 0.07

* Formerly C. nigrificans

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The Principles of Canning for Fishery Products: Selection of Thermal Processing Conditions

The purpose of sterilizing cans of fishery products is to rid the container and the contents of all pathogenic micro-organisms and to prevent. spoilage by non-pathogenic contaminants under normal storage conditions. Selection of processing conditions necessary to fulfill these criteria is based upon experimental studies in which the rate of heat penetration to the slowest heating point (SHP) of the container is measured during simulated retorting cycles.

The data from these trials (or from suitable reference sources) are .used by fish canning technologists to determine the processing temperatures and times necessary to render the canned product commercially sterile. Manufacturers of canned fish (and all low-acid canned foods) can specify their thermal processes in terms of target Fo values, where the Fo value is a measure of thermal processing severity.

Having selected an appropriate Fo value (which may be far in excess of that required to reduce to an acceptably low level, the probability of survival of Clostridium botulinum spores as may be the case when the process is designed to bring about bone softening) the canner then adopts a time and a temperature for the thermal process which will ensure its delivery at the SHP of the container.

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The Principles of Canning for Fishery Products Preservation

What is Canning?

Canned fish

Canning is a method of preserving food in which the food is processed and sealed in an airtight container, providing a typical shelf life ranging from 1 year to 5 years and under specific circumstances a freeze dried canned product can last as long as 30 years and can still be safely consumed. The process was first developed as a French military discovery by Nicolas Appert in 1810. The packaging prevents microorganisms from entering and proliferating inside.

The Principles of Canning
The purpose of thermal processing during manufacture of canned fishery products is the destruction of bacteria by application of moist heat. Only having satisfied the safety requirements of protecting consumer health, and the commercial requirements of preventing non-pathogenic spoilage, does the canner set about choosing a thermal process schedule that will optimise the sensory quality of the finished product.

Of the bacteria contaminating fishery products, some (the pathogenic bacteria) cause food poisoning while others only spoil the food. Of particular concern to fish canners is the possibility of there being contamination by Clostridium botulinum which, if present, can form heat resistant spores capable of withstanding a mild thermal process. As this micro organism can grow at the pH of fish flesh it is important that the processor ensure that all his cans have received a process that is sufficiently severe to kill spores and vegetative forms of the bacterium. Survival of Clostridium botulinum, after the thermal process, is an extreme health risk as low-acid canned foods (pH > 4.5) support growth of the organism, and under certain conditions will also favour formation of the neurotoxin responsible for outbreaks of botulism.

Sterilization is a heat treatment given foods capable of supporting the growth of heat resistant spore forming bacteria. Sterilization processes destroy all pathogenic contaminants and all other micro organisms capable of growing under normal storage conditions; survivors of the process will be extremely heat resistant spores which pose no health risk and only grow at elevated temperatures (= 40 ºC). Rather than make canned foods absolutely sterile, canners aim for "commercial sterility" which means that the contents are safe (as all pathogenic microorganisms have been destroyed) and shelf-stable at normal storage temperatures. Were the thermal process designed to make all cans absolutely sterile, there would be unnecessary loss of sensory and nutritional quality without there being any increase in the safety of the product.

The higher the temperature of sterilization the greater is the rate of thermal destruction, which is why canners process their canned fish in steam under pressure rather than in water at atmospheric pressure. The rate of thermal destruction is also affected by the nature of the product (liquids heat faster than solids) and the container size (large cans of fish packed in brine take longer to reach lethal temperatures, than do small cans containing the same product). The total sterilization effect of a thermal process can be expressed as the sum of all the sterilization effects achieved by all the time-temperature combinations throughout the entire thermal process. By convention, sterilizing effect is expressed in standard units of minutes at 121.1 ºC, so that. an entire processing cycle is expressed as being equivalent, to holding the product at 121.l ºC for a given time. The unit of sterilization is the Fo unit, where an Fo value of one minute is equivalent to holding the product at 121.1 ºC for one minute and then cooling it instantly.

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A Guide for Canning Vegetables

A Canned vegetables

As all we known that all agricultural products is perishable. This perishable characteristic is all because of a high water content level consisting in them. This condition happened to vegetables as one of agricultural products that need time to reach to the consumers. 

Therefore, it's need a technique to preserve vegetables to not defect when it's ready to be consump by the consumers. One of the preservation techniques that reliable for vegetables is canning.

All vegetables, except tomatoes, require processing in a pressure canner with a weighted control or dial gauge. Because tomatoes are more acidic, they can be safely processed in a boiling water bath.

Food Safety Concerns

A deadly form of food poisoning, botulism, can occur when low-acid foods are improperly processed. The higher temperatures of the pressure canner are necessary to ensure that any Clostridium botulinum spores are killed. If the organism is present in canned low-acid vegetables, botulism toxin can be produced. Even sealed containers without any visible sign of spoilage can contain botulism toxin.

• To avoid the risk of botulism, make sure your pressure canner is in good working order; check the gauge yearly for accuracy; follow all canning recommendations exactly.
• Since the rate of heat penetration and acidity is affected by the combination of foods used, do not can vegetable mixtures such as vegetable soup or chili sauce unless you have a laboratory tested recipe.
• Never thicken vegetables prior to canning. For mixed vegetables look up the processing time for each vegetable in the mixture. Use the processing time for the vegetable that requires the longest processing time.
• Always check home canned vegetables carefully for signs of spoilage before and after opening. When opening, watch for spurting liquid, an off odor, or mold.

If there is any doubt in your mind whether home canned food food is spoiled, don’t use it. Burn any spoiled food or dispose of it so that it will not be eaten by humans or animals. Also, be sure to boil low-acid vegetables for 10 minutes before tasting or serving.

Select and prepare vegetables carefully

• Choose only fresh, young, tender vegetables. Wash thoroughly, small amounts at a time, under running water or through several changes of water. Lift the vegetables gently out of the water so dirt washed off will not settle back on the food. Rinse the pan or sink between washings.
• The number of quarts of canned food from a given amount of fresh vegetables depends on quality, condition, maturity, and variety of the vegetable; the size of pieces packed; and the way the vegetable is packed-raw or hot pack.
• Generally, the following amounts of fresh vegetables (as purchased or picked) make 1 quart when canned:
• Asparagus: 2 to 4 pounds
• Beans, lima, in pods: 3 to 5 pounds
• Beans, snap or green: 1 to 3 pounds
• Beets, without tops: 2 to 3 pounds
• Carrots, without tops: 2 to 3 pounds
• Corn, sweet, in husks: 3 to 6 pounds
• Peas, green, in pods: 3 to 6 pounds 
• Pumpkin or winter squash: 1 to 3 pounds
• Spinach and other greens: 2 to 6 pounds 

Use standard jars and lids

• Use only jars and two-piece lids made especially for canning. Check jars and lids for cracks, chips, dents and rust; these defects cause sealing failures. Commercial jars such as those for mayonnaise are not recommended for home canning because they are not designed for use with two-piece lids and because the glass is more likely to break during processing. Wash jars in hot, soapy water; rinse well. Prepare lids and bands according to manufacturer’s directions.
• Mineral deposits or hard water film on jars can be removed by soaking the empty jars for several hours in a solution of 1 cup vinegar per gallon of water. To avoid mineral deposits on jars during processing add 1⁄4 cup vinegar per gallon of water used in the pressure canner.

Fill jars and adjust lids

• Vegetables can be packed raw, or preheated and packed hot. See Table 1 (released in next posting) for specific directions.
• Most raw vegetables should be packed closely because they shrink during processing. Corn, lima beans and peas absorb liquid and expand when processed so should be loosely packed. To ensure proper heat penetration, do not pack vegetables too tightly. Vegetables packed hot should be at or near boiling temperature and should be packed loosely.
• Use the hot cooking liquid and add boiling water, if needed, to fill the jar and cover the food for both raw and hot packed vegetables. If the vegetables at the top of the jar are not covered they may darken.
• Salt is not needed for preservation in canned products but can be added for flavor. Use 1 teaspoon per quart or 1⁄2 teaspoon per pint.
• The space between the packed food and liquid and the top of jar is called headspace. The amount of headspace required is given with details for canning each vegetable. Too much or too little headspace will affect jar seals.
• Slide a non-metallic spatula between food and side of jar to remove any air bubbles. Wipe jar rims to remove food particles that might interfere with sealing. Adjust lids.

Check altitude

• As altitude increases, water boils at a lower temperature (below 212° F). Lower temperatures are not as effective for destroying organisms. Therefore, when using a pressure canner, the pressure must be increased as altitude increases.

Process in a pressure canner

• Partially fill canner with 2 to 3 inches of water. Place jar rack and sealed jars in canner. Fasten lid. Heat on high. After steam exhausts for 10 minutes, add weighted gauge or close petcock. Allow canner to reach designated pressure. Start timing when designated pressure is reached. Regulate heat to maintain a constant pressure.
• Process for the time recommended in Table 2 (released in next posting). Do not reduce the processing time.
• When processing is complete, remove canner from the burner.
• Allow the canner to cool at room temperature until it is fully depressurized.
• This will take 30 to 60 minutes depending on the type of canner. Do not rush the cooling by setting the canner in water or by running cold water over the canner.
• Do not open the vent or lift the weight to quicken the reduction of pressure.
• When the pressure has dropped to zero, carefully open the petcock or remove the weighted gauge. Wait 2 minutes, then slowly release and remove the canner lid.

Remove and store jars

• Take jars from canner and set upright on a rack or folded cloth away from drafts. Do not tighten the screw bands.
• Allow jars to cool undisturbed for 12 to 24 hours, then check for sealing failures. 
• To test jar, press center of lid. If lid is down and will not move, jar is sealed. Remove screw bands carefully. 
• Wash, dry, label, and store jars in a cool, dark place. If any jars have not sealed, place in refrigerator and use within two days. Vegetables can be reprocessed with fresh liquid, new lids and clean jars, and the full processing time, but quality will be affected.

Source: 

• Textbook of Food Science and Technology

Next Post: Guidance for Preparing and Packing Vegetables

Home Canning Meats and Poultry

These recommendations are for West Virginia conditions (maximum altitude, 4,000 feet). For canning directions in other locations, consult your county Extension office.

Fresh or frozen meats and poultry can be canned safely at home. Since these products are low-acid foods, they must be processed in a pressure canner to be sure that spoilage organisms, including those that cause botulism, are destroyed. For a safe product, follow all canning directions exactly.

To get ready for a safe canning season:

• Be sure your pressure canner is in good working condition and that the pressure gauge was checked for accuracy this season at your county Extension office. The weighted gauge—the one that jiggles—doesn’t have to be tested.
• Check the gasket. If it is nicked, replace it.
• Have sufficient jars on hand and discard any with nicks and/or cracks. Use only pint or quart Mason jars made specially for home canning. Straight-sided or wide-mouth jars are easier to work with.
• Buy new lids. Old screw bands can be used if they are not rusted or bent.

Just before canning:

• Be sure your knives are sharp.
• Sanitize all cutting surfaces. (See containers of household bleach for directions.)
• Review directions for using the pressure canner.

Yields of Canned Food from Fresh

The number of jars you can fill with meat or poultry depends upon the size of pieces and the way the meat is packed. For a quart jar, allow about the following amounts of fresh untrimmed meat with bone or ready-to-cook chicken:

After Canning:

• To cool, place hot jars, well separated, on rack or folded cloth away from drafts.
• Cool at room temperature for 12 to 24 hours.
• When jars are cool, remove the screwband and test the seal. If the lid did not seal, you have three options:

Option 1: Use the food the same day or refrigerate immediately and use within several days.

Option 2: Freeze the food in the same jar, if tempered for freezing, by increasing the headspace to 11/2 inches, or freeze it in another freezer container. Mark that the food needs to be boiled in an uncovered container for 20 minutes before using.

Option 3: Reprocess. Remove the lid and check the jar seal surface for tiny nicks. Fully process the jar for the correct time and at the correct temperature.

Before Using:

As an added safety precaution, boil home-canned meat or poultry for 20 minutes in an uncovered saucepan. If the meat smells spoiled during boiling, destroy it without tasting. If, after boiling, the meat or poultry is not to be used at once, or if it’s to be used in salads or cold dishes, refrigerate it immediately. Use within 1 to 2 days.

Canning and Processing Directions

Meat Preparation—beef, veal, pork, lamb, and large game animals.

If meat is home produced, chill it to 40 degrees F or lower immediately after slaughter.

This is to prevent spoilage and allow for tenderizing. If the meat is to be held longer than 2 to 3 days, freeze it at 0 degrees F or lower until ready to can. Then thaw it slowly in the refrigerator.

Keep all meat as cool as possible during preparation for canning. Remove meat from bones, and trim off gristle, bruised spots, and fat. During processing, fat can rise to the top of the jar and keep the lid from sealing. Handle meat quickly and process as soon as the containers are packed.

Cut the meat into convenient sizes for your needs—strips, cubes, chunks, slices, chops, or larger pieces.

If desired, strong-flavored wild meats can be soaked for 1 hour in brine water (1 tablespoon salt per quart of water) before cutting it into pieces. Rinse before heating. Then process according to the following directions.

Strips, Chunks, or Cubes of Meat (beef, pork, veal, venison, bear, and lamb)

Procedure: Choose quality chilled meat. Remove excess fat. Remove large bones.

Hot Pack

Precook meat until rare by roasting, stewing, or browning in a small amount of fat. Add 1 teaspoon of salt per quart to the jar, if desired. Fill jars with pieces and add boiling broth, meat drippings, water, or tomato juice (especially with wild game), leaving 1-inch headspace.

Raw Pack

Add 1 teaspoon of salt per quart to the jar, if desired. Fill jars with raw meat pieces, leaving 1-inch headspace. Do not add liquid.

Wipe mouth of jar with a clean cloth; adjust lids and process.

Dial Gauge Pressure Canner

Process at 12 pounds of pressure for 75 minutes for pints and 90 minutes for quarts.

Weighted Gauge Pressure Canner

Process at 15 pounds of pressure for 75 minutes for pints and 90 minutes for quarts.

Stock (Broth)

Beef: Saw or crack fresh trimmed beef bones to enhance flavor. Rinse bones and place in large stock pot or kettle, cover bones with water, add lid, and simmer 3 to 4 hours. Remove bones, cool broth, and pick off meat. Skim off fat, add meat removed from bones to broth, and reheat to boiling. Fill jars, leaving 1-inch headspace. Adjust lids and process.

Dial Gauge Pressure Canner

Process at 12 pounds of pressure for 20 minutes for pints and 25 minutes for quarts.

Weighted Gauge Pressure Canner

Process at 15 pounds of pressure for 20 minutes for pints and 25 minutes for quarts.

Chicken or Turkey: Place large carcass bones in a large stockpot, add enough water to cover bones, cover pot, and simmer 30 to 45 minutes or until meat can be easily stripped from bones. Remove bones and pieces, cool broth, strip meat, discard excess fat, and return meat to broth. Reheat to boiling and fill jars, leaving 1-inch headspace. Adjust lids and process.

Dial Gauge Pressure Canner

Process at 12 pounds of pressure for 20 minutes for pints and 25 minutes for quarts.

Weighted Gauge Pressure Canner

Process at 15 pounds of pressure for 20 minutes for pints and 25 minutes for quarts.

Ground or Chopped Meat (beef, lamb, pork,sausage, veal, venison, and bear)

Procedure:

1. Select fresh, chilled meat. With venison, add 1 part high-quality pork fat to 3 or 4 partsvenison before grinding. Use freshly made sausage, seasoned with salt and cayenne pepper (sage may cause bitter off-flavor). Shape chopped meat into patties or balls, or cut cased sausage into 3- to 4-inch links.
2. Cook until lightly browned. Ground meat may be sauteed without shaping. Remove excessfat.
3. Fill jars with pieces. Add boiling meat broth, tomato juice, or water, leaving 1-inch head space. Add 1 teaspoon of salt per quart, if desired.
4. Adjust lids and process.

Dial Gauge Pressure Canner

Process at 12 pounds of pressure for 75 minutes for pints and 90 minutes for quarts.

Weighted Gauge Pressure Canner

Process at 15 pounds of pressure for 75 minutes for pints and 90 minutes for quarts.

Chicken or Rabbit

Procedure: Choose freshly killed and dressed, healthy animals. Large chickens are more flavorful than fryers. Dressed chicken should be chilled for 6 to 12 hours before canning. Dressed rabbits should be soaked 1 hour in water containing 1 tablespoon of salt per quart and then rinsed.

Remove excess fat. Cut the chicken or rabbit into suitable sizes for canning. Can with or without bones.

Hot pack

Boil, steam, or bake meat until about two-thirds done. Add 1 teaspoon salt per quart, if desired. Fill jars with pieces and hot broth, leaving 11/4-inch headspace. Adjust lids and process.

Raw pack

Add 1 teaspoon salt per quart, if desired. Fill jars loosely with raw meat pieces, leaving 11/4-inch headspace. Do not add liquid. Adjust lids and process.

Dial Gauge Pressure Canner

With bones (hot and raw pack)---process at 12 pounds of pressure for 65 minutes for pints and 75 minutes for quarts.

Without bones (hot and raw pack)---process at 12 pounds of pressure for 75 minutes for pints and 90 minutes for quarts.

Weighted Gauge Pressure Canner

With bones (hot and raw pack)---process at 15 pounds of pressure for 65 minutes for pints and 75 minutes for quarts.

Without bones (hot and raw pack)---process at 15 pounds of pressure for 75 minutes for pints and 90 minutes for quarts.

Chile Con Carne

• 3 cups dried pinto or red kidney beans 
• 51/2 cups water 
• 5 tsp. salt (divided) 
• 3 pounds ground beef 
• 11/2 cups chopped onions 
• 1 cup chopped peppers of your choice (optional) 
• 1 tsp. black pepper 
• 3 to 6 Tbsp. chili powder 
• 2 quarts crushed or whole tomatoes 
• Yield: 9 pints 

Procedure: Wash beans thoroughly and place them in a 2-quart saucepan. Add cold water to level of 2 to 3 inches above the beans and soak 12 to 18 hours. Drain and discard water. Combine beans with 51/2 cups of fresh water. Bring to a boil. Reduce heat and simmer 30 minutes. During the last few minutes of cooking, add 2 teaspoons salt. Stir and boil for 2 more minutes. Drain and discard water. Brown ground beef, chopped onions, and peppers, if desired, in skillet. Drain off fat and add 3 teaspoons salt, pepper, chili powder, tomatoes, and drained cooked beans. Simmer 5 minutes. Caution: Do not thicken. Fill jars, leaving 1-inch headspace. Adjust lids and process. 

Dial Gauge Pressure Canner 

Process at 12 pounds of pressure for 75 minutes for pints only 

Weighted Gauge Pressure Canner 

Process at 15 pounds of pressure for 75 minutes for pints only.

This publication is adapted from the United States Department of Agriculture’s Complete Guide to Home Canning, 1994, and Kerr Home Canning and Freezing Book, 1996. Reviewed by Amy O’Dell, M.S., Graduate Student, and Guendoline Brown, Ph.D., Nutrition and Health Specialist,

1999.