Category: Uncategorized

Pasteurization and Sous Vide

Working in the food manufacturing industry, pasteurization is a critical step to ensure food safety. Now I don’t have any industrial ovens or equipment at home but I can get fairly close with home equipment. A follow up to my strawberry compote recipe http://192.168.2.65/strawberry-rhubarb-compote/ I decided to try pasteurizing the drink so I can extend its shelf life as I will be bringing these on a outdoor trip a week from now.

I will not get too deep into thermal death kinetics (but its a great topic for another time). But for pasteurization time and temperature matter most. I can use high temperature for a short time or lower temperature for a longer time. For this case I pasteurized at 90c for 1 hour (plus the startup time). I setup my sous vid for 194F (90c) and a probe along side it and put in my bottles and jars to be pasteurized (picture bellow). In industry I have used Datapaq at few different jobs to confirm the time at temperature which is critical to process and was able to emulate that with my own probe & logger. I was able to confirm exactly 1 hr at 90c and almost 2 hours at 80c which proves sufficient for pasteurization.

This was a fun project and I was very happy to see such a consistent temperature profile, now if only temperature profiles were so “text book” at work :D.

Sous Vide Temperature Accuracy & Reliability

I have purchased a new sous vide machine and as always it has to be broken in and tested. I have found digital temperature sensors to be repeatable but sometimes inaccurate and so offset have to calculated for each of these machines.

I have a master chef unit and the test was controlling water at 132F (55.56 C). I dropped in a logging probe to confirm this. The chart below shows a very tight temperature grouping but the average is at 55C and not the 55.56 the sous vide was controlling to. So in the end I have a very repeatable and controllable unit but it is 0.5C off which I can alwaysaccount for.

Easter Rum Baba

An Easter classic, the rum baba makes a delicious treat. It is a bit intensive and messy but well worth the effort. One key factor is the raisins themselves have to be soaked for at least 4 hours as when trailed at shorter intervals they weren’t retaining any of the flavor. Additionally the soaking liquid has to be applied hot and can quite literally be squeezed into the cakes.

Zesty Tuna Couscous

A quick and easy lunch. Couscous was cooked in a lemon juice mixture, flash chilled and the tossed with cucumber, feta, tomato and onion. Micro greens and a little tomatoe rose garnish. Nice and appealing.

Understanding Fridge Temperature

Following the basis of http://192.168.2.65/quick-temperature-logging-probe/ I setup a wireless temperature probe to monitor the temperature in my fridge because who knows what the temperature is when the dial is set to 3 😉 (there is a joke about a fridge that goes to 11 somewhere there).

Results were very surprising as the 95% confidence interval was so tight together I though something was wrong. Looking at the trend chart we see that there might be some oscillations if we tracked for longer but this was already a 3-4 day time frame O_o. It would be extremely shocking to me if there were oscillation with a period of 7-8 days.Follow ups.

Follow ups & Notes

  • Trial with different locations as obviously positioning further away from cooling coils will have higher temperatures.
  • Trial with larger battery bank to get large time frame trending
  • This was done on a cheap & old mini fridge so there might be value in testing newer hardware.
  • The fridge was heavily stocked with high heat capacity items so hysteresis may be playing a bit of a part here.
  • Higher polling frequency, though 15s should be more than frequent enough.
  • …

Current Home Dashboard

This is a snapshot of my current dashboard I have mounted in my room. All the key stats for my server and network as well as weather details and time.