Japanese “onsen” hot spring eggs 温泉卵

After coming up with, what I thought were reasonably safe conditions for pasteurizing shell eggs at home using Sous vide, the next natural step was to make Japanese "Onsen" eggs 温泉卵. One thing I have to point out is that a Japanese "onsen" egg is not a Western-style soft boiled or poached egg. For Westerners, a  totally cooked but still tender white with a runny egg yolk are the combination that constitutes a perfect soft "boiled" or "poached" egg. Japanese onsen eggs are just the opposite—the white is still loose and a bit slippery but the yolk is congealed to the texture of thickened cream  or custard or "nettori" ねっとりtexture and moist.  To make this combination you exploit the fact that the yolk congeals at a slightly lower temperature than the white. Also another fact to consider is that the "jelling" process of egg proteins occur slowly and progressively and the duration of cooking also make a difference in the end results.



The above is my sous vide "onsen" eggs. I served it cold with cubes of ripe avocado, garnished with finely chopped scallion, and "real" wasabi.  I poured cold sauce which I made over it.  The green is water cress added for color.



The above is how the yolk looks after cutting into it using a spoon. It has a viscous and moist texture but is not runny. The white is not firmly congealed and is very tender still slightly slippery but does not have a "raw" texture. As far as I am concerned this is a perfect "Onsen" egg. You could make this without Sous vide but with it, you can control the temperature precisely to make perfect and safe "Onsen" egg every time.



I consulted the blog by a Japanese molecular scientist and gastronome who described making the "ultimate onsen egg " 究極の温泉卵 using a circulator/water bath with 12 combinations of temperature and duration (in Japanese). I followed his recommendation of 67C (152.6C) for 30 minutes. Again there is no mention of the initial temperature of the eggs in this post. I used eggs directly from the refrigerator (40F or 4.4C) and after 30 minutes were up, immediately submerged the cooked eggs in ice cold water for for 15 minutes, wiped them dry and stored them in the refrigerator.

With this high-temperature of 67C in sous vide, I estimated that the egg yolk will reach 54.4C sometime conformably before 30 minutes, extrapolating from the Dr. Cox's chart at 60C. The fact, also, that the egg yolk was homogeneously congealed  indicates to me the temperature of the egg yolk was way above 54.4C*, probably near or at 67C, without significant temperature gradients. Although I used Pasteurized shell eggs this time, I am reasonably comfortable that I can safely used regular shell eggs for this recipe.

*Requires 5 minutes at 54.4C to accomplish "lethal" kill of salmonella, reportedly.

Sauce: I had leftover dashi broth which I made from a "Dashi pack" (kelp and bonito). I added mirin, sake and light colored soy sauce 薄口醤油 and let it come to gentle boil for few minutes, let it cool to room temperature and then refrigerated. You could use diluted "Mentsuyu"noodle dipping sauce 麺つゆ from a bottle as well.

To serve, I could have just seasoned with soy sauce or salt and used it as a topping for salad, noodles or a rice dish. The way I served the eggs is a good one if you just want to enjoy onsen eggs. I was a bit worried my wife might reject the looser texture of the egg white but she said although soft it was cooked not raw. She really liked the dish especially the custard-like texture of the egg yolk.

Compared to soft boiled or poached eggs, onsen eggs are easier to keep and serve.  Once made, they can be kept in the refrigerator safely for, at least several days, and, since the white is not attached to the shell, the eggs slip out easily by just cracking the shell open (No more struggling to get the shell off soft boiled eggs).

Sous vide and home pasteurization of shell eggs スービイと自家製滅菌卵

Please also see the second version of home pasteurized eggs.

Salmonella contamination of hens eggs and chicken meat doesn’t appear to be a big problem in Japan. Raw and undercooked eggs and chicken meat are frequently consumed on such items as raw egg on rice (卵かけ御飯), moon-gazing soba noodle (月見そば) and "tataki" or " sashimi" of chicken tenderloins (とりわさ). In the US, salmonella food poisoning is a serous problem. Eating any product with raw egg in it is risky. Common sources of salmonella food poisoning are home-made mayonnaise, Caesar salad dressing, and raw cookie dough as well as sunny-side-up and soft boiled eggs with runny yolks, Some states (New Jersey being one) even outlawed restaurants from serving sunny-side-up eggs for a while. Certainly nobody in their right mind would consume raw or under cooked chicken meat.

If we want a dish with raw eggs or runny yolks, we use pasteurized shell eggs which we posted before. Low temperature pasteurization for shell eggs is a patented process by Dr. and Mr. Cox. Only one producer (Davidson's safe eggs) is using this patented method.

Recently I acquired a very reasonably priced home sous vide machine. There are at least three products in this category and after reading the review I settled for "Anova" sous vide machine (see below).



The submersible part contains a heating coil and agitating propeller under a metal cover with vertical slits and the  top has a good sized touch sensitive color LED screen for setting the temperature and time. It does quite well heating up the water, maintaining the temperature and providing good circulation. I double checked the temperature using a digital thermometer and found the temperatures registered in the water with the sous vide was within 0.7 F of the temperature registered on the thermometer so it was quite accurate. I am not sure, however, which one is more accurate. In addition the temperature was even thorough out the water bath.



The first thing I wanted to try was to pasteurize shell eggs at home. This has to be done at a  temperature low enough that the egg white and yolk don’t coagulate but high enough and long enough to reduce the salmonella to safe levels. I read about low-temperature pasteurization of shell eggs including the patent filing of Dr. and Mr. Cox and Food Lab's guide to slow-cooked. sous-vide-style eggs. Some suggestions regarding "home pasteurization of shell eggs" I found on the web appear to have no scientific basis and did not sound like they would accomplish adequate pasteurization at all.

I determined that  at 130F for more than 2 hours (2 hours 20minutes to be exact in the eggs I “pasteurized” but 3 hours will be on the extremely safe side) would be the most reasonable to accomplish the goal of pasteurization. But I do not have any microbiological proof to confirm this. So I have to add a word of caution that the results of this method are not guaranteed--use at your own risk.  If you are interested how I came up with this conclusion, please read below*.

I sous vided shell eggs directly out of the refrigerator for 2 hours and 20minutes at 130F. I thought that the long time at low-temperature would eliminate possible temperature gradient issues. I immediately soaked the sous vide eggs in ice cold water for 10-15 minutes, dried the surface and placed them in the refrigerator. My wife suggested that I mark the eggs before putting them with the others in the fridge. She helped me to write "P" for "pasteurized" on the eggs using a pencil (below). (She told me that when she was young this was a method her mother used to distinguish hardboiled eggs from raw ones—its no fun cracking the last egg in the house to make a cake only to discover it is hardboiled!)



When I cracked open the home pasteurized eggs after a few hours of refrigeration, the yolk and white were liquid and looked about the same as an unpasteurized egg.



The second egg (front) had a very slight cloudiness (Which I see occasionally even in the commercial pasteurized shell eggs) but was still liquid.



I scrambled these two eggs and made a stuffed omelet. It cooked exactly like any un-pasteurized egg but I did not have to worry about having undercooked egg in the omelet. Its texture and taste were fine as well.

* Sous vide low-temperature pasteurization of shell eggs.

Dr. and Mr. Cox patent application is a good example of lawyers writing a scientific/technical article. It is next to impossible to figure it out. This patent  contained not just pasteurization of shell eggs but other egg products, scrambling eggs in their shells (why do you need to do this is beyond me),  and a method of replacing naturally occurring gasses in shell eggs with mixture of  sterile air and gasses to prolonged the shelf life. This is a chart they included in the application.



I interpreted this chart this way; at 129.5F (54.4C), the egg white did not coagulate ("irreversibly damaged") at least up to 120 minutes but the yolk temperature reached 54.4C after 105 minutes and maintaining this temperature for 5 minutes would be "lethal" (for salmonella, I assume). At 140F (60C), eggs can be sterilized a bit shorter than 30 minutes  but before this happens "irreversible damage" of egg white will happen. Any other temperatures in between, pasteurization can occur before the egg white starts to "thicken before irreversible damage" but you need to stop heating before 120 minutes to accomplish pasteurization without "irreversibly damaging" the white. To my dismay, the document did not specify the initial temperature of the eggs in this experiment.The initial temperature could make a difference in the amount of time needed to eliminate a temperature gradient and have the yolk achieve a temperature high enough to be lethal to salmonella.

In any case, from this chart and Food Lab's guide to slow-cooked. sous-vide-style eggs, I concluded at 130F, you could keep the shell eggs for a long time (at least 2 hours to be safe) without coagulating the egg white or egg yolk and obtain the adequate pasteurization at the center of the egg yolk. I think that low temperature and long heating time should eliminate any variables stemming from the initial temperature of the eggs and temperature gradient.

Now that I think I can safely produce pasteurized eggs, I will still buy Davidson's Pasteurized eggs but, just in case, we now have a back up plan. More sous vide cooking is coming.

P.S. After receiving a comment from an anonymous reader, I am adding the new references below. Dr. Schuman's article has soild microbiological proof, albeit only 57C and 58C were tested in details. As per this paper, to be absolutely safe (non-detectable salmonella or total bacteriocidal level), 57C (134F) for 75 minutes is recommended. I am not sure if egg white will become cloudy at this temperature,  butI will try and let you know. The below is from the reference 2 below.

1. Schuman JD, Sheldon BW, Vandepopuliere JM, and Ball HR Jr. Immersion heattreatments for inactivation of Salmonella enteritidis with intact eggs J Appl Microbiol. 1997 Oct;83(4):438-44.
   
2.  USDA Document "Pasteurization of Liquid Egg Products and Shell Eggs"
   

Octopus salad 蛸のもろ味味噌サラダ

The last time I went to the Japanese grocery store, I could not resist buying a leg of boiled octopus. We had a thick portion of leg thinly sliced and we enjoyed it dressed in mustard miso and vinegar dressing 芥子酢味噌.  I cut the remaining portion into small chunks or "Butsu-giri" ぶつ切りand made this sort-of Japanese-Italian salad.  The dressing was made of "moromi miso" 諸味味噌, yuzu juice and extra virgin olive oil (EVOO). We had this with a red wine and it went Ok.



I sprinkled on Japanese one flavor red pepper flakes.



Ingredients:
Boiled octopus leg, cut into small chunks (amount arbitrary).
Japanese cucumber , one cut into small cubes (cut into 4 long pieces along the length and then cut across).
Celery, two stalks, veins removed and cut into small cubes.
Daikon, one 1/3 inch slice, peeled and cut into small cubes (I think Jicama will also work)

Dressing:
Moromi miso, about 1 tbs
Yuzu juice, about 1 tsp (I used one from the bottle)
EVOO, about 1 tsp

I just dressed the above ingredients in the dressing. After tasting I added a bit more moroni miso. I placed the salad on the water cress and sprinkled Japanese on one flavor red pepper flakes 一味唐辛子.

The combination of moromi flavor with cucumber and celery works well. The addition of EVOO adds an interesting "Italian flavor". This is an interesting small salad to start the evening. This probably would go better with sake or beer.

Stir fried squid and celery イカとセロリの炒め物

This is an example of my “quickly-make-something-as-we-savor-sake” routine style. Actually, this is the quick magical transformation of a sashimi drinking snack to a warm snack with just the application of heat (plus some other stuff) . The particular evening I did this we had three drinking snacks, and reached the point when we decided squid sashimi was enough. I decided to change what we did not eat into a new dish. Again, this is a variation of the sautéed squid with celery dish. I served it on a scallop shell.



The squid is from frozen squid sashimi in a package which was already dressed with wasabi and soy sauce.

I obliquely sliced celery and minced garlic. I melted butter in a frying pan and sautéed the garlic and then the celery. When the celery was mostly done I added the squid (including water cress which I had served under the sashimi).  When the squid became opaque (it took only 10 seconds or so), I seasoned it with soy sauce.

I served this on a scallop shell (I stabilized the shell which rolled a bit because of its rounded shape by adding a mound of Kosher salt on the plate under it. I again sprinkled on Japanese one flavored red pepper flakes 一味唐辛子.

For quick conversion dish, this was not bad. The combination of soy sauce and butter cannot go wrong.

Three otoshi #2 続お通し３品

We really like multiple "otoshi" drinking snacks. This is another example which I made one weekend. From left to right are: "Nattou, marianted chiai tuna with egg york" 卵黄入り鮪の血合い納豆, "Crab and cucumber dressed in vinegar" かにと胡瓜の酢の物 and "squid sashimi dressed in soy sauce and wasabi" イカ素麺.

"Chiai" is the very dark portion of tuna which I removed from the blue fin tuna toro block we got. I marinated the chiai in equal amounts of soy sauce and sake in the refrigerator. As before, I just mixed nattou, marinated chiai tuna, and egg yolk (Pasteurized shell egg). I garnished it with thinly cut perilla. Chiai usually tastes gamey and strong but this preparation makes it much more palatable.This dish is pretty high on the slime factor scale so it is not for the faint-hearted or for consumption by “J-Q public” particularly in the United States but Yamada Taro 山田太郎 (equivalent to John Q. Public in Japan) may like it.  But we (including my wife) certainly like it.

The second is a very standard "sunomono" 酢の物. The crab meat came from Catalina Offshore products. We have never tried this before but, again, because some items we wanted such as sea urchin or amaebi were not available, I decided to try this cooked crab meat. This was a great disappointment.  It was all claw meat of stone crab but it was not easy to remove the hard shell (only tip of the claws) and thin cartilage. It all came out as small pieces. We can get much better packaged lump crab meat at our local grocery store. In any case, we had a Japanese cucumber for a change and made this crab and cucumber sunomono. As usual, I thinly sliced the cucumber, salted it and let it stand for a few minutes and then wrung out the moisture. I dressed it with sushi vinegar with splashes of yuzu juice (from the bottle).

The below is another version I made the day before with addition of tomato and daikon threads which was dressed in ponzu (leftover from garish I used for tuna sashimi).

The below is a packaged and frozen sashimi of squid I got from our Japanese grocery store. I simply dressed it with soy sauce and wasabi and served on the top of water cress.

These are nothing special or new but good drinking snacks to start with your cold sake.

Barbequed pork fried rice バーベキューポークの焼き飯

We used to make fried rice チャーハン炒飯 all the time but it’s been a while since I last made it. The last time I posted fried rice was in 2009. I am sure many people have their own secret recipe for making the best fried rice such as mixing a beaten egg into the rice before frying etc. Some consider it important to keep the rice from not sticking together but, in my opinion, if that is what you want, just use long grain rice. I am inclined to stick to my old-tried-and-true method of making fried rice. One innovation I have made is to use frozen rice. (I keep any left over rice in Ziploc bags in the freezer). Freezing reduces the moisture and making it much easier to make fried rice.


Today, we had an end piece of hot smoked pork loin which we barbecued last weekend in the Weber grill. Since I also had blanched broccolini, I added that, too.



Since this was a lunch, I also quickly made "nameko" mushroom なめこ and tofu miso soup.



Ingredients (2 small servings):
Rice: about 1 cup, previously frozen, thawed by microwaving for 40-50 seconds, crumbled.
Barbecued pork: This is the end piece of hot smoked pork loin. I sliced and then cut into half inch squares (amount arbitrary).
Onion: Half of large onion, finely chopped
Garlic: 3 fat cloves, finely chopped
Ginger: Tip of pinky sized, sliced and finely chopped
Shiitake mushroom: 2 large fresh, cut into small pieces.
Broccoini" 4 stalks, blanched, the stalks cut into small pieces, the flowering end just separated.
Egg: one beaten and seasoned with salt and pepper for scrambled egg.

In a non-stick frying pan on medium flame, I added vegetable oil (2 tsp) and dark sesame oil (1 tsp). I added garlic and ginger and slowly fried until fragrant and added the onion. I kept sautéing for a few more minutes. I then added the shiitake mushrooms, the stalk of broccolini, and the pork, sautéed for a few more minutes and seasoned with salt and pepper. I set it aside on a plate, wiped the pan clean, added vegetable oil (1/2 tsp) and made scrambled egg and set it aside.

I again wiped the pan clean, added vegetable oil (2 tsp) and dark sesame oil (1/2 tsp) on high flame. I added still cold but thawed  (kernels separated) rice into the pan and started stir frying. After all the rice kernels got coated with oil, I flattened the rice to have some browning on the bottom and then stir fried again until rice was thoroughly hot and cooked, I added the vegetable/pork mixture and the flowering end of the broccolini, seasoned with salt and pepper. At the last moment, I added soy sauce along the edge of the pan (so that the soy sauce first hit the hot metal surface of the pan before getting mixed into the rice, which adds more flavor from the soy sauce) and stir fried some more.

I put the fried rice on the plate, garnished with roasted white sesame seeds, fried "aonori" 青海苔powder and the scrambled egg. For the miso soup, I used granulated instant "dashi", canned nameko mushroom, chopped scallion and tofu. Although "akadashi" 赤出し味噌 is most proper for this soup, we do not particular like akadashi (too bitter) and I used regular "awase"miso 合わせ味噌 (between red and white miso).

For a weekend lunch, this was pretty good. I particularly enjoyed the miso soup with the fried rice.

Decadent breakfast with caviar, scrambled egg and creme fraiche キャビアと卵の豪華版朝食

Caviar is  not an "Izakaya" item but we tend to get carried away sometimes. Since the last time we had real Beluga caviar was ions ago, we decided to get both American Sturgeon as well as Beluga for a taste comparison and to refresh our memories. As before we got these from Fine Caviar.

This is American sturgeon. According to the fine caviar web site;

"Hackleback Sturgeon - (Scaphiryhnchus platoryhnchus) is indigenous to the Missouri and Mississippi River systems"



So this one is from wild-caught sturgeon. As you can see the grain of the caviar is fine and the color is black. The flavor is very subtle but not fishy with a nice salinity. The crunch and pop are great.

This is imported Beluga caviar which appears to come from "farm raised" sturgeons in "Eastern Asia" (which ever country that may be). Again quoting form the website;

"The eggs of the Huso Dauricus Sturgeon are raised in advanced farms located in Eastern Asia."



As you can see the grain of the caviar is much larger and the color is gray. In terms of the flavor, the difference is very subtle. We are not sophisticated enough to say one is better than the other or Beluga is worth the extra expense.



In any case, here is Beluga caviar on blini, with homemade creme fraishe and chives, which was wonderful.



Next morning, we decided to go past just a scrambled egg breakfast. So we put the eggs on blini and added American Sturgeon caviar.



Fish eggs for breakfast may not be everybody's idea of a good breakfast but this combination was quite good and luxurious, at least, to us.

I think we had enough caviar to last us for a while.