Mellow​ ​Cooling​ ​Mode
A​ ​Food​ ​Safety​ ​Statement
Mellow abides by the FDA food safety guide to make sure ingredients are always safe to
consume. Immediately after inserting your food packet in the water bath, the water begins to
cool​ ​down​ ​to​ ​a​ ​safe​ ​temperature.​ ​The​ ​water​ ​will​ ​remain​ ​in​ ​this​ ​Cold​ ​Zone​ ​until​ ​it​ ​is​ ​time​ ​to​ ​cook.
Why​ ​Mellow’s​ ​Cooling​ ​Feature​ ​is​ ​safe

1) Mellow takes into consideration pathogenic growth safety according to FDA food code
for​ ​our​ ​unique​ ​Cooling​ ​system:
a) Even though it may take a few hours to reach the 40ºF mark, it reaches 70ºF and
consequently 50ºF quickly enough to maintain the ingredient safe until it reaches
40ºF​ ​and​ ​below;
b) At temperatures below 50ºF, bacterias start approaching lag phase [1] and their
reproduction rate is almost deactivated - meaning the food is safer for much
longer​ ​then​ ​if​ ​you​ ​leave​ ​it​ ​in​ ​your​ ​counter​ ​top.
2) Our cooking algorithms take into account full pasteurisation times for most ingredients;
for fish, because it is cooked in the considered danger zone, we don’t allow user to keep
the food in water bath for more than 20 minutes after cooking is done (even though the
considered​ ​dangerous​ ​range​ ​is​ ​for​ ​a​ ​few​ ​hours​ ​of​ ​exposure).
How​ ​does​ ​Mellow​ ​Cooling​ ​system​ ​work
Depending on several factors, like the amount of water in the container and the room
temperature, Mellow may take a few hours to cool down. However, even in the most extreme
cases, it still reaches the FDA recommended temperature within the prescribed time limit to
keep your food safe. The following table depicts the maximum holding times from 30ºF to 125ºF
based on FDA code time-temperature controls [1], using the Ratkowsky bacterial growth
prediction​ ​equation​ ​[2]:

 Table​ ​1​.​ ​Maximum​ ​Holding​ ​Times​ ​and​ ​Temperatures

These times are derived from the growth of pathogenic microorganisms in food. They are based
on the cold holding standard established in the FDA Food Code that food at 41°F can be held
for 7 days. These times at specified temperatures are based on the assumption that the food is
of​ ​average​ ​quality​ ​when​ ​obtained​ ​from​ ​the​ ​food​ ​market​ ​or​ ​supplier.
The​ ​published​ ​FDA​ ​2013​ ​Food​ ​Code​ ​also​ ​dictates​ ​that:
“If time without temperature control is used as the public health control up to a maximum of 4
hours, the food shall have an initial temperature of 5ºC (41ºF) or less when removed from cold
holding temperature control, or 57ºC (135ºF) or greater when removed from hot holding
temperature control. (...) If time without temperature control is used as the public health control
up to a maximum of 6 hours, the food shall have an initial temperature of 5ºC (41ºF) or less
when removed from temperature control and the food temperature may not exceed 21ºC (70ºF)
within​ ​a​ ​maximum​ ​time​ ​period​ ​of​ ​6​ ​hours.”​ ​[3]
According to V.K. Juneja - who is a researcher of Residue Chemistry and Predictive
Microbiology for the USDA’s Eastern Regional Research Center, Pennsylvania - as storage
temperature decreases, the rate of growth of pathogens decreases. For example, the growth of

 pathogenic strains of ​listeria monocytogenes ​in fish at temperatures between 71-86ºF (22-30ºC)
becomes an hazard after 3 hours, but if the fish is kept under 70ºF (21ºC) the maximum
cumulative exposure times increases to 7 hours. These maximum exposure time can be
extended to 1 day, if the fish is kept under 50ºF (10ºC) or even 7 days, if the temperature is as
low​ ​as​ ​31.3.-41ºF​ ​(-0.4​ ​-5ºC).​ ​[4]
Deeper​ ​scientific​ ​approach

This is a common kind of info-graphics (figure 1) that is too general, for a consumer with no
food​ ​safety​ ​background​ ​and​ ​that​ ​has​ ​no​ ​motivation​ ​to​ ​go​ ​deeper​ ​into​ ​the​ ​subject.

Figure​ ​1​.​ ​Fallacious​ ​“Danger​ ​Zone”​ ​graph:​ ​40ºF-140ºF

FDA food codes and Hazards and Controls Guidance are more explicit about the danger zones
than popular fallacious graphs. ​Some temperatures included within the commonly cited
“danger zone” are not dangerous, and others not included within this “zone” are dangerous
under​ ​some​ ​conditions.
“​This guidance represents the Food and Drug Administration’s (FDA’s) current thinking on this
topic. It does not create or confer any rights for or on any person and does not operate to bind
FDA or the public. You can use an alternative approach if the approach satisfies the
requirements of the applicable statutes and regulations​. If you want to discuss an alternative
approach, contact the FDA staff responsible for implementing this guidance. If you cannot
identify the appropriate FDA staff, call the telephone number listed on the title page of this
guidance.​”​ ​[4]

 Given this example of pathogenic growth (table A-2), the popular “danger zone” (between 40ºF
to 140ºF) is not factually accurate. In fact, food pathogens can multiply between 29.7ºF and

 126.1ºF, while spoilage bacteria begin multiplying at 23ºF [3, 5, 6]. The available info is often
generalized and we are taught that food pathogens do not multiply below 40ºF because it takes
days​ ​for​ ​food​ ​pathogens​ ​to​ ​grow​ ​to​ ​a​ ​dangerous​ ​level​ ​at​ ​this​ ​temperature.
Another​ ​expert​ ​approach

Frank L. Bryan [​president of Food Safety Consultation and Training1], discusses and analyses
how pathogenic bacterial growth is not as linear as suggested by the fallacious “Danger Zone”
graph​ ​shown​ ​above.​ ​He​ ​also​ ​suggests​ ​to​ ​update​ ​info​ ​for​ ​a​ ​more​ ​realistic​ ​model​ ​such​ ​as:

1

​ ​in​ ​Lithonia,​ ​GA,​ ​which​ ​specializes​ ​in​ ​conducting​ ​HACCP​ ​system​ ​evaluations​ ​in​ ​food​ ​processing​ ​plants,​ ​food​ ​service
establishments​ ​and​ ​food​ ​markets,​ ​identifying​ ​CCPs,​ ​and​ ​recommending​ ​control​ ​criteria​ ​and​ ​monitoring​ ​and​ ​verification
procedures.​ ​Internationally​ ​known​ ​for​ ​his​ ​work​ ​in​ ​food​ ​safety,​ ​Bryan​ ​served​ ​as​ ​a​ ​scientist​ ​director​ ​at​ ​the​ ​Centers​ ​for​ ​Disease
Control​ ​and​ ​Prevention,​ ​Public​ ​Health​ ​Service​ ​from​ ​1956-1985,​ ​where​ ​he​ ​focused​ ​on​ ​foodborne​ ​disease​ ​epidemiology,​ ​control
and​ ​training,​ ​and​ ​was​ ​an​ ​active​ ​member​ ​of​ ​the​ ​International​ ​Commission​ ​on​ ​Microbiological​ ​Specifications​ ​for​ ​Foods​ ​from
1974-1996.​ ​He​ ​served​ ​as​ ​chairman​ ​of​ ​the​ ​Committee​ ​on​ ​Communicable​ ​Diseases​ ​Affecting​ ​Man,​ ​International​ ​Association​ ​of
Food​ ​Protection​ ​(IAFP)​ ​from​ ​1970-1999,​ ​and​ ​as​ ​consultant/advisor​ ​to​ ​the​ ​World​ ​Health​ ​Organization,​ ​Pan​ ​American​ ​Health
Organization,​ ​Food​ ​and​ ​Agriculture​ ​Organization​ ​of​ ​the​ ​United​ ​Nations

 Mellow​ ​Summary

In​ ​summary,​ ​there​ ​are​ ​several​ ​things​ ​to​ ​take​ ​in​ ​mind:
1) Mellow’s software will not allow foods to be hold above their maximum holding times
according to the FDA code; fish would hold for a maximum time of 1 day and meat 2
days. Experts in this area (such as Frank L. Bryan) have a wider perspective about this
subject and the scientific tables for holding times are much more detailed than their
simplified​ ​versions.
2) Mellow cooling system performance has all the above pre-requisites into account; it
reaches 40ºF and prior to it reaches 50ºF in safe timings - ​”food shall have an initial
temperature of 5ºC (41ºF) or less when removed from temperature control and the food
temperature​ ​may​ ​not​ ​exceed​ ​21ºC​ ​(70ºF)​ ​within​ ​a​ ​maximum​ ​time​ ​period​ ​of​ ​6​ ​hours”​ [​ 2].

3) Our cooking algorithms take into account full pasteurisation times for most ingredients;
for fish, because it is cooked in the considered danger zone, we don’t allow user to keep
the food in water bath for more than 20 minutes after cooking is done (even though the
considered​ ​dangerous​ ​range​ ​is​ ​for​ ​a​ ​few​ ​hours​ ​of​ ​exposure).
4) Mellow takes into consideration pathogenic growth safety according to FDA food code
for​ ​our​ ​unique​ ​Cooling​ ​system:
a) Even though it may take a few hours to reach the 40ºF mark, it reaches 70ºF and
consequently 50ºF quickly enough to maintain the ingredient safe until it reaches
40ºF​ ​and​ ​below;
b) At temperatures below 50ºF, bacterias start approaching lag phase [1] and their
reproduction rate is almost deactivated - meaning the food is safer for much
longer​ ​then​ ​if​ ​you​ ​leave​ ​it​ ​in​ ​your​ ​counter​ ​top.
5) As food safety is always our priority, we block users to use our Cooling Mode in app if
the initial water temperature is above 29ºC (84.2ºF) since the cooling rate could
compromise​ ​the​ ​ingredient.
In the end, as Mellow cools down the food to reach the Cold Zone (40ºF), the explanation above
demonstrates that the ingredients are safe to consume based on the FDA Food Code. Even
under the most extreme environments taken into consideration, Mellow’s cooling method safely
cools​ ​the​ ​water​ ​down​ ​and​ ​passes​ ​through​ ​70ºF​ ​and​ ​50ºF​ ​within​ ​the​ ​FDA​ ​approved​ ​timeframe.

References

 [1] Snyder, O.P. 1998. Updated guidelines for use of time and temperature specifications for holding and storing food in retail food
operations.​ ​Dairy​ ​Food​ ​Environ.​ ​Sanit.​ ​18(9):574-579.
[2] Ratkowsky, D. A., R. K. Lowry, T. A. McMeekin, A. N. Stokes, and R. E. Chandler. 1983. Model for bacterial culture growth rate
throughout​ ​the​ ​entire​ ​biokinetic​ ​temperature​ ​range.​ ​J.​ ​Bacteriol.​ ​154(3):1222-1226.
[3]​ ​U.S.​ ​Department​ ​of​ ​Health​ ​and​ ​Human​ ​Services,​ ​U.S.​ ​Food​ ​and​ ​Drug​ ​Administration,​ F
​ DA​ ​Food​ ​Code​,​ ​c2013
[4] U.S. Department of Health and Human Services, U.S. Food and Drug Administration, ​Fish and Fishery Products Hazards and
Controls​ ​Guidance​,​ ​2011,​ ​fourth​ ​edition
[5] Snyder, Jr., O.P., 2006. Food Safety Hazards and Controls for the Home Food Preparer. Technical Report. Hospitality Institute of
Technology​ ​and​ ​Management.
[6] Juneja, V.K., Whiting, R.C., Marks, H.M., Snyder,O.P., 1999. Predictive model for growth of Clostridium perfrigens at
temperatures​ ​applicable​ ​to​ ​cooling​ ​of​ ​cooked​ ​meat.​ ​Food​ ​Microbiology​ ​16,​ ​335-349
Mellow​ ​Inc.
Ângela​ ​Chan​ ​and​ ​Filipe​ ​Leonor
17​ ​November​ ​2017