Cooking Time and Temperature

Ingesting the wrong E. Coli bacteria can ruin your picnic. And your kidneys.

As the food we cook is generally meant to be fed to humans, making sure it is safe for consumption is important. Heating food to destroy harmful bacteria is a common way to reduce risk for foodborne illness. Controlling cooking time and temperature allow a cook to maintain acceptable safety while causing minimum damage to food texture and taste.

Background

There are two types of foodborne illness: infection and food poisoning.

Infection occurs when microorganisms directly penetrate the body and grow. Sometimes these organisms can also secrete toxins. Examples include salmonella, trichinella spiralis, E. coli (certain strands), Listeria monocytogenes, and prions like BSE (mad cow). Noninvasive infection primarily involve organisms such as the tapeworm that live inside humans and, while there, secrete toxins that do damage.

Food poisoning is caused by toxins already in the food. This causes the most rapid onset of symptoms (1-6 hours) as toxins are already present and no infection needs to happen. Examples include C. botulinum, Salmonella and Staphyloccus aureus.

The possibility of symptoms from both bacteria and their toxins is why we cannot leave meat sitting in our refrigerator for too long, cook it to a "recommended temperature", and then still eat it. We could kill the active microorganisms but their toxins wouldn't go away. Foodborne illness happens on many different foods, but most people don't cook things like vegetables to make them safe. As a result, this entire guide will focus on the other problem of killing bacteria before they have already contaminated meats.

Time and Temperature

Pasteurization depends on time and temperature. As temperature increases from freezing, bacteria thrive and multiply more rapidly up to a point where they start dying. For example, each 15.2 minutes at 130 degrees Fahrenheit kills 90% of intact Salmonella bacteria. At 140 degrees Fahrenheit, this happens every 2.76 minutes. Each time this 90% killing happens is called a decade reduction. So a 2D reduction is 99%, a 99.99% reduction is 4D, and so on. If that 15.2 minute reduction is 1D, then a 5D reduction would take 15.2x5 or 76 minutes, killing off 99.999% of bacteria.

General FDA recommendations for fresh food are to reach a reduction level of 6.5D, or 99.99997% of pathogens present. When we're cooking on the stovetop or in the oven, there is no way to have this level of control over keeping the food at a particular temperature throughout much less time its holding for pathogen reduction against the guidelines. When we cook sous vide, however, we can estimate the time it takes even the center of the food to reach a temperature, and hold it at a pasteurization temperature to achieve the recommended guidelines.

Cooking Charts and Tables

Extended and Simplified 6.5D Salmonella Reduction Table

°Celsius	°Fahrenheit	Time
52	125.6	5h 14m
52.2	126	4h 46m
52.8	127	3h 48m
53	127.4	3h 28m
53.3	128	3h 1m
53.9	129	2h 24m
54	129.2	2h 17m
54.4	130	1h 54m
55	131	1h 31m
55.6	132	1h 12m
56	132.8	1h
56.1	133	57m 31s
56.7	134	45m 44s
57	134.6	39m 51s
57.2	135	36m 22s
57.8	136	28m 55s
58	136.4	26m 23s
58.3	137	23m
58.9	138	18m 17s
59	138.2	17m 28s
59.4	139	14m 32s
60	140	11m 34s
60.6	141	9m 12s
61	141.8	7m 39s
61.1	142	7m 19s
61.7	143	5m 49s
62	143.6	5m 4s
62.2	144	4m 37s
62.8	145	3m 41s
63	145.4	3m 21s
63.3	146	2m 55s
63.9	147	2m 19s
64	147.2	2m 13s
64.4	148	1m 51s
65	149	1m 28s
65.6	150	1m 10s
66	150.8	58s
66.7	152	44s
67	152.6	39s
67.8	154	28s
68	154.4	26s
68.9	156	18s
70	158	11s
71.1	160	7.1s
72.2	162	4.5s
75	167	1.4s
76.7	170	0.7s
77	170.6	0.6s
79.4	175	0.23s
80	176	0.18s
82.2	180	0.07s
85	185	0.02s

See Also

• Is it done yet? a food safety guide from the USDA.

References

• Mhyrvold, Nathan et al. Modernist Cuisine: The Art and Science of Cooking. Bellevue, Wash.: Cooking Lab, 2011. ISBN 9780982761007. Vol. I pages 110-112, 192-194.
• Baldwin, Douglas E. Sous Vide For the Home Cook. Incline Village, Nev.: Paradox Press, 2010. ISBN 978-0-9844936-0-9