The Kitchen Formula Calculator v3

Notes On Eggs, And An Egg Test In Thailand

The Composition Of An Egg

• Eggs contain dozens of different proteins, various essential fats, and a wealth of B vitamins, minerals, and vital nutrients such as Selenium and Choline. They are relatively low calorie foods that pack a lot of nutritional benefits.
• Proteins are long-chain Amino acids. Some of these proteins occur mainly in yolks, others only in egg whites (aka albumen), some in both. 
• Egg white makes up about 2/3 of the total weight of a fresh egg, but depending on breed of chicken that laid the egg, this varies. Some references claim the albumen can be as little as 60%, the yolk as much as 40% of the total, but in my experience that is not typical. [see the results of my real world egg testing below.  
• Egg white, aka albumen, contains about 10-12% protein, 88-90% water. It is a little less than 60% of the total protein content of an egg, and consists of 4 alternating layers of thick/thin albumen. The albumen contains dozens of proteins. 
• The composition of egg yolk is about 50% protein, 30% fat, the rest being vitamin and mineral content & water weight. Egg yolk contains 13 different vitamins & minerals, plus Selenium, Choline, and essential fats Omega 3 and Omega 6. Several of the vitamins are fat soluble only. Egg yolk also contains Lecithin, an effective emulsifier, and a rich source of Choline.
• Contrary to popular belief, egg yolk is more likely to extend your life and well being, than to end it. One significant essential nutritional element found in egg yolk is Choline. Choline is good for your brain, among other things. A single egg yolk provides about 25% of the daily requirement for it. Choline can only come from one’s diet. It’s a very good thing not to be deficient in, but most Americans are. You can read for yourself many more details about the wonders of the egg.

What Do Eggs Do In Food Formulations?

• Eggs provide structure, texture and mouthfeel. Eggs also act as emulsifiers because egg yolk contains (and is the best source of) Lecithin, an effective emulsifier.
• Eggs have a coagulative property. They can change from liquid to solid, or semi-solid (gel) states. It is an irreversible phase change, true of all protein cookery, except for gelatin.
• Coagulation is achieved when exposed to heat (protein denaturation), by mechanical means (whipping), in the presence of acids (lowers the temp required for coagulation), or sugar (raises the temp for coagulation). Other factors include alkali (spurs egg white gelation), and enzymes, useful for cheesemaking, can also aid coagulation.
• In short, eggs thicken such stuff as custards, and act as a binder when used in more complex recipes for which it is a lower proportion of the total, e.g. any type of forcemeat.

Coagulation  

• Egg proteins are tightly folded & coiled individual molecular units, held together in a somewhat globular shape by weak chemical bonds. When eggs are heated or whipped, agitation on a molecular level occurs, and these bonds begin to breakdown; the structures unfold. 
• Protein molecules carry an electrical charge of course. Oppositely charged ends of the unfolded protein molecules attract, linking together in a 3d matrix, i.e. they coagulate. 
• What water content within the yolk and white that exists gets trapped in this matrix. During cooking, the matrix expands as water inside turns to steam. As with any baked item, the initial geometrical configuration of the item changes during the process.
• Depending upon the amount of egg protein present in a formulation, and the degree of heat or mechanical action applied, the resulting structure is either semi-solid (e.g. sabayon), or solid of varying degrees of density (Crème Caramel > omelette). 
• If combined in a more complex formulation such as cookie dough, or the aforementioned forcemeat, they simply add structure, and richness, more or less, depending on the part of the egg used. 
• Egg yolks add more richness, less structure; egg whites add less richness, more structure. This is due to the nature of the proteins in each part, as well as, the amount of protein content in each part. Egg whites have more protein than do yolks. Protein is structure. 
• Egg whites have about double the gel power of egg yolk. An egg white has greater capacity to create a stable foam, and greater leavening effect as a result. Egg white can be whipped to a volume approximately 8 times its original volume; egg yolks, perhaps 4 times only.
• Albumen can become rubbery when not carefully cooked. High heat applied will make albumen more so. Egg type matters in this regard as well. Duck egg albumen, for example, is more prone to developing a rubbery texture than a Chicken egg because it has different proteins in it, and different overall protein content. 

Effective Range For Coagulation 

• With dozens of different proteins dispersed in the yolks, the whites, or both, eggs will coagulate over a range of temps. 
• Egg whites gel at lower temps than do egg yolks. Egg whites begin to gel starting at 62.2ºc (144ºf), and continue to do so to greater densities as the temp approaches 65ºc (149ºf). The gel becomes a more dense structure as its internal temp increases. Yolks do the same, but at higher temps: 65ºc (149ºf) to 70ºc (158ºf). As for whole eggs, the range reflects both extremes of it’s parts. beginning to gel at 62.2ºc (144ºf), and finishing at 70ºc (158ºf).

Factors That Affect Coagulation, And The Rate Of Coagulation

• A number of things affect gelation. As noted, these are heat, mechanical action, acids, sugars, alkali, and enzymes. The actual ratio of egg yolk to albumen matters as well. This ratio will vary from one egg to the next even within the same size grade. 1 cup of eggs is always marginally different from another cup. Even so, the practical effect is likely to be insignificant. Thus my not rigorously tested stipulation about the weight of “1 egg”, and it’s parts has not had a practical affect upon outcomes. For large production volumes such as practiced on industrial scales (hostess Twinkies, McD's, Campbells etc.), variations matter both for the outcome of the formula, and for the costs to produce it. What do serious production concerns do? They do not specify volumes of ingredients, they specify weights of; problem avoided. [And to that point, is partly the inspiration for my recipe transcription project: to rewrite all my old recipes without reference to volume measures.]
• When whipping whole eggs, egg yolks, or egg whites, the ability of the final structure to remain stable depends on the earnestness of the process, and if other ingredients have been added. For example, a simple basic meringue (aka Swiss meringue) can begin to destabilize over time, weeping liquid (Syneresis) from its foamed matrix. This is why a meringue topped pie, if not consumed the same day, might better use an Italian meringue instead of a Swiss meringue. The Italian version is mechanically created by whipping the whites just as for the basic meringue, but it’s also cooked. The sugar called for is added in the form of a syrup cooked to 116.5ºc - 118ºc (240ºf - 245ºf). The same technique is used for making a Parfait Glacé, Bombe Apparel, and other pastry prep. Cooking the egg whites this way adds greater structural stability because the cooked egg foam matrix is more durable than one that’s only been whisked together. as well, it eliminates chances of food poisoning. 
• The degree of mechanical (whisking) action determines the density of the structure (soft peaks / stiff peaks), while whisking to an extreme can cause Syneresis.
• The actual amount of eggs in a solution, or other mixture determines the amount of structure to be expected. More eggs = greater structural stability. By manipulating this, bakers can create more delicate custards, or more sturdy ones depending upon the ultimate uses for them; a delicate custard for Crème Caramel, a more robust custard for Crème Pâtissièr. A single egg, added directly, can add enough structure and richness to a typical home formula for cookie dough because the dough has a sizable amount of flour, whereas more eggs, whipped to a pale lemon colored ribbon stage, are required to create a delicate Genoise batter that holds it shape after baking because there’s a very much lower proportion of flour used.
• Adding liquid ingredients such as broth, wine, milk, or cream obviously delimit the final gel structure and density according to the ratios in which they are added. 
• Adding sugar affects the coagulation point of eggs, increasing it considerably. If tempered eggs are whisked into just heated milk or cream, they will begin to coagulate at the temperature range noted above, but if sugar is added to the liquid ingredients, the coagulation temp of the eggs rises from about 62.2ºc (144ºf) to about 82.2ºc (180ºf), and can be cooked further to about 85ºc (185ºf) without fear of curdling the eggs in the custard solution. 
• In formulations that include starches such as puddings, and Crème Pâtissièr / Crema Pasticcera, the starches not only add their own structural power, they slow down the rate of egg coagulation when cooking such solutions. This is very helpful to eliminate egg curdling. In fact, you need to bring the ingredients to a definite boil to ensure proper thickening.
•  The addition of a very small dose of starch slurry is a common Asian cooking technique for a less rubbery albumen formation, and a moister / creamier result for scrambled eggs, or omelette.
• As noted, a simple meringue doesn’t have a very durable coagulation profile. It will naturally begin to destabilize over time. A cooked meringue such as a French meringue (heated over a Bain Marie prior to final machine mixing), or better yet, an Italian meringue will create a much more stable matrix.
• Lipase is an enzyme frequently used in cheesemaking to help make a more defined curd/whey break. 
• Calcium Chloride is often added to help with the structure of cultured milk/cream products (yogurt, crème fraîche, mascarpone, sour cream etc) if using a pasteurized milk product. While it is not, per se, a coagulant, it restores the natural balance of Calcium and protein in Casein (lost during pasteurization) which is beneficial for coagulation.
• Acidic ingredients will lower the temperature at which eggs begin to coagulate. Depending upon the Ph level of the acid added, the effect will be more or less. This is because acids have a pronounced effect on proteins of any sort. Some scant amount of acid, if added to egg whites, helps when making a meringue due to the tenderizing (denaturation) effect upon the protein in the egg whites.
• Alkali have a similar effect for lowering the coagulation temp when the product is heated, but the effect acts upon egg whites alone. Alkaline ingredients spur the gelation of egg white protein. 

Eggs in a recipe are, generally speaking, fairly critical elements, but there’s some leeway. For the past few years in Thailand I've been using the eggs I normally buy from the local market for all purposes, including baking. The egg size I buy is one step up from the Thai equivalent to the USDA size Large egg that is the standard in American kitchens and recipe writing. In the ideal kitchen, all ingredient quantities would not be specified as “pieces”, nor in volume measures, but as a gram weight value. Specifying the weight of egg in a recipe makes better sense, but it’s testimony to the leeway that exists in recipes that the typical instruction for 1 egg, or 2 yolks, or 10, works just fine. This practical fact, however, doesn’t suit my needs for the ongoing recipe transcription project I'm doing. Using a different size egg means there will be marginal changes, and effects. What will vary is ultimate volume, density of structure, and richness of the product. As these are not absolutes, they are acceptable as a range which the average diner will not be able to note the difference. Thus, the ambiguous quantity “1 egg” persists.

So What Does “1 Egg” Really Mean?

In American kitchens, when a number of, or volume of eggs is given for the quantity required for some formulation, the number/volume always means “number/volume of USDA size Large eggs”. Size Large is taken for granted, and it is what is meant by “1 egg”. Regarding American kitchens and eggs, that much i knew, but i did not know how the eggs I buy in Thailand correspond. I mean, I know I’ve been buying a larger egg than the American standard for recipes, but I didn’t know the specifics about Thai eggs, Thai grading standards, or how they match up to the American grading standards. 

A quick check with the Thai Agriculture Standard showed that the corresponding egg to the USDA size Large egg is the Thai number 2 egg. Knowing this was not the end of things however. If you want to stop using volume, and by-the-piece measures for writing your recipes, then a weight value in grams is the data you require. According to my not-so-very-laboratory-scrupulous-but-real-world-of-cooks-in-kitchens test (see below), “1 egg” means 50.3 grams. Rounding that, then 50 grams is the answer. 

This is corroborated by the very reputable website www.aquacalc.com. That site’s much more scrupulous testing procedures reports that the volume to weight conversion for 1 cup of whole eggs requires 4.86 eggs, and that 1 cup of whole eggs weighs 243 grams. if 243 is divided by 4.86, the result is 1 egg = 50 grams. You can stop reading here if that’s all you needed to know, or read on if curious.

Egg Grading 

In America, the USDA regulates egg grading for quality and size. Size grades for shell eggs are: Jumbo, X-Large, Large, Medium, Small, and Peewee. Each has a designated minimum weight per dozen; Jumbo 30oz / dozen, X-Large 27oz, Large 24oz, Medium 21oz, Small 18oz, Peewee 15oz.

https://www.ams.usda.gov/sites/default/files/media/Shell_Egg_Standard[1].pdf

USDA egg grading also specifies different quality grades. These refer to the visual condition of the egg, both the exterior and interior, and also to the characteristics of the yolk and white. Grade AA is the highest quality, then Grade A, Grade B. Grade AA indicates the whites are the firmest, contain the least amount of loose white, the yolks stand the highest, and shell appearance and cleanliness is the best.

For both purchasers and knowledgable cooks, a range of recommended uses apply to each grade. Grade AA is not always the right choice. Grade AA does not indicate better organoleptic quality, i.e. it doesn’t mean it tastes better. Grade AA only implies it offers specific benefits depending upon ultimate use. Smart operators ought to consider a lower quality grade based on the ultimate use for the product. Taste and nutritionally, all grades are equal. Keeping two different grade specifications on hand for many food inventory items can make sense after taking into account considerations such as storage space, and inventory turnover ratio. For example, if a perfect looking sunny side up or poached egg is required, then Grade AA is the go-to, Grade A being also acceptable, but for general cooking purposes, Grade B (omelette, scrambled eggs, sauce making, use in pâtissèrie and baking) is a better choice; tastes as good, functions the same, costs less. Capable purchasers will specify the correct size and grade, or sizes and grades required to produce the entire range of products for their operation. It is my experience that small operations too often, either don’t understand the importance of matching product specs to the range of various actual uses in their kitchens, or they are under informed about purchasing strategy in general.

Grading Standards Compared

Here in Thailand, egg grading is much like the USDA system, but eggs are graded not as Jumbo, Extra Large, Large, Medium, Small, Peewee. Egg grading is designated not by dimension, but as a numerical value; number 0 being the largest, 1 being next largest, then 2, 3, 4, and 5. Nevertheless, to illuminate the number value, the Thai Agricultural Standard cross references the number value to the same dimensional verbiage used by the USDA. Number 0 is also designated as Jumbo, number 1 is X-Large, 2 is Large, number 3 is Medium, number 4 is Small, number 5 is Peewee.

https://www.acfs.go.th/standard/download/eng/hen egg_ENG.pdf

Just as in USA, the Thai standard has specified minimum weights, but it’s a bit different. Whereas the USDA standard gives a minimum weight per dozen eggs for each weight spec, in Thailand the weight spec applies per egg, stating both a minimum, and maximum weight in grams. According to the Thai Agricultural Standard, the  number 0 egg is >70 grams, the number 1 egg is a range from >65-70 grams, number 2 is >60-65 grams, number 3 is >55-60 grams, number 4 is >50-55 grams, and number 5 is >45-50 grams. As in America, these refer to the weight of shell eggs.

To see how the two systems compare, determining a Thai weight per dozen must be done. For Thai number 0 eggs, simply multiply 70 grams times 12, then divide by 28.35 (grams per ounce). You will arrive at a the equivalent Thai weight grading standard per dozen number 0 eggs of >29.63oz/dozen. This is virtually the same as the USDA size Jumbo egg standard of 30oz. Do the same for the Thai number 1 minimum weight spec, and the value is 27.5oz/dozen. very slightly more (.5 gram is less than 1/56th of an ounce) than the USDA minimum per dozen for size Extra Large. Again for the Thai number 2 egg, and the value derived is 25.4oz/dozen minimum weight. 

You can see that the Thai Agricultural Standard has copied the USDA standards, only changing the qualifier for eggs from dimensional to numerical. It is unsurprising that what the US government agencies set up as standards are mimicked widely throughout the world. Not every country has the financing to conduct, and design their own standards for the wide range of daily commercial, health, and safety of their populations. Nevertheless, if you go to any market in Thailand, it’s the grade number that you need tell the vendor you desire. Otherwise you’ll just get a curious look. 

When the two standards are compared, it’s clear that what most closely approximates the egg size used in American kitchens (size Large), is in Thailand the number 2 egg, 60-65 grams.

What Does The Egg Size Grade Get For The Cook?

What a baker, or cook gets when they crack eggs for recipes, either whole, or separated is variable because eggs are not lightbulbs. They are organic elements, and no two eggs, even in the same size grade, are the same. Even if they weigh precisely the same, the actual process of cracking them for use in a formulation means there is loss. For most cooks, separation is done by hand, and more or less egg is lost with each cracking. The weight of the yolks will vary, as will the weight of the whites. 

How much egg white, or yolk is lost during the handling? Since kitchens are not laboratories, and cooks have other things going on, the actual yield of a USDA size Large, or Thai number 0 egg minus its shell will not be consistent. More or less white remains in the shell, or is lost on the fingers of the cook, yolks get busted; loss occurs. The amount of loss will not practically affect the outcome. The relevant point is, what is the weight of an egg? We want to write recipes in metric weight measures, not volumes.

The egg size grade isn’t always the final word on the weight of one egg to another, even if both eggs weigh the same in shell. Disregarding loss due to handling after cracking, the liquid weight might vary simply because shell weight can vary, and the actual binding power of an egg, or its ability to foam can vary marginally because within each egg the actual ratio of egg white to egg yolk varies, thus does its weight, and it’s processing characteristics. These marginal variations are not to a degree that make a practical difference. Only the weight of significance for doing volume to weight conversions.

• Various other factors that can affect the relative liquid weight of an egg include the breed of bird, the housing system (free range, or caged), the age of the bird, and the mineral content, and density of the egg shell, and so, the porosity of the shell.
• Younger hens lay lighter eggs, Older ones, near 1 year of age, lay the heaviest. 
• The effects of the housing system show mixed results. Some studies show free range eggs to be heavier, others show it for caged hen eggs. 
• Structure of the shell, and shell porosity undergo changes after laying. A 21-day-old egg can lose up to 5% of its total weight due to the carbon dioxide content of the albumen dissipating through the shell as its Ph rises with age. Water loss through the shell occurs simultaneously. 
• One chicken breed isn’t the same as another. The color of the shell is not a factor, but different breeds may produce a range of color in the yolks from pale yellow to almost red. 
• Chicken eggs have different characteristics from duck eggs, even if they taste the same. 
• The size of the egg itself has an effect on the ratio of the weight of the shell to its liquid content. Obviously, bigger eggs have more shell weight, but not necessarily more as a percentage of the total weight of the egg. On the other hand, size Medium eggs are known to have thicker shells than sizes larger than medium, thus the ratio of shell weight to liquid weight of an egg is greater in medium size eggs. This is not necessarily a reason to avoid medium size eggs. Choosing a USDA size Medium egg (or its Thai equivalent, number 3) makes sense if you are cooking them in shell. The thicker shells are easier to peel without scarring the surface of the cooked egg white.
• The ratio of egg yolk to egg white in one cup of eggs can vary. Albumen (egg white) is predominantly water weight, while yolks have much less water, and more solids. As a consequence, there is no absolutely accurate volume to weight conversion for an egg. One cup of whole eggs might weigh more or less. This cup of eggs vs that cup can vary.
• Freshness of the egg matters because changes occur to the proportions of egg yolk to egg white as they age. Loss of water occurs from the albumen. Egg yolks are unaffected. An older egg still tastes the same; it cooks differently. Not a big issue unless you are making poachers, or sunny side ups.
• “Freshness” can be interpreted as the ratio of loose white to firm white. This, as well as, the appearance of the yolk is affected by storage conditions. Stored at room temperature, which is how eggs in Thailand are stored and displayed, will insure the whites are almost always predominantly loose, and yolks become less proud. 
• In Thailand it is very hard to find eggs that look good when poached. When cracked, the more viscous part of the albumen is almost non-existent. Loose white predominates. Consequently, the looseness of the whites make the poached egg look very raggedy. Much of the white is useless, floating freely and unattached. The only way around this issue is to par cook the shell eggs sous vide, then finish in poaching liquid on the order, or at service time.

For all the considerations mentioned above, and for accuracy and convenience, many kitchens buy cracked eggs not whole eggs. Cracked eggs are usually frozen, and come either whole, or separated. There are other benefits such as uniform nutritional profiles, and sanitary handling and packing. Practically speaking, frozen egg whites foam better than unfrozen ones. Freezing ruptures the albumen matrix, making the whites more runny. They whip up faster, and to greater volumes. Frozen eggs have other benefits including being pasteurized. If used to make cold preparations the frozen egg is safer. 

Why The Egg Test?

I've long used 55 grams as my standard for the volume to weight conversion of 1 cracked egg because I buy the Thai number 1 egg, and use it for all purposes. I stipulated 18g for the weight of 1 yolk, and 36g for the white. Based on my real world egg test results, those assumptions will need be revised for reasons described below.

For a small commercial kitchen operation, or a home kitchen, whether the cook uses a large egg (Thai number 2), or an extra large egg (Thai number 1) won’t have a noticeable practical difference. Nevertheless, it became more important to know more precisely what size of Thai egg corresponds closest to the USDA size Large egg because the USDA size L is the given for recipes in America. 

I’m in the long process of transcribing my 45-year-old hand written logbook of pastry shop recipes into The Kitchen Formula Calculator spreadsheet that I devised. As was typical of that era, those recipes were written using a combination of volume measures (teaspoons, tablespoons, cups, quarts, and gallons), and American Standard weight measures (ounces and pounds). My pastry shop formulae are written to produce 7, 8 or even 20 units of flan, torte, or pie; unsuitable for either smaller restaurant operations, or home scenarios. I needed to get these scaled down to realistic home yields. Re-scaling recipes is a daily feature in kitchens that is error prone, and time consuming. Most cooks do it by creating a "multiplier", either a whole number to scale up, or a fractional to scale down. Simply multiply whatever ingredient quantity is specified to re-jigger it according to the need to make more or make less. 

I still use those pastry shop recipes because they’ve been tested, and work well, but every time I wanted to make Croissant dough, or Savarin, Kaiserschmarn, a Paris-Brest, or an Engadiner Nuss Torte, or any of the hundreds of other recipes I had acquired over the years, I had to do volume to weight conversions, or at the very least (and most inefficient) use a fractional multiplier to figure out greatly reduced volume ingredient quantities. My revised needs, meant that I required just enough to produce a single unit of Savarin, or of Croissant dough sufficient to supply my own consumption. Re-scaling recipes is a frequent situation for almost all cooks. I invented a better way.

I’ve posted extensively, and in detail about The Kitchen Formula Calculator that I designed, about it’s virtues, and how to use it. It’s based upon a specific mathematical logic that does for all recipes not bread what Baker’s Math and Baker’s Percentages do for bread formulae. The Kitchen Formula Calculator, and the Cook’s Math, and Cook’s Percentages I devised that the tool is based upon was created specifically to handle this re-scaling problem, but the tool is also an ideal recipe writing and recipe recording platform. For professional chefs, in addition to using it for recipe writing/recording, it becomes a very good, clean, and easy format for recording menus written over the years at various establishments; the menu cycles, station mise en place required, and for recipe costing. The Kitchen Formula Calculator makes it easy to keep an ongoing record of all menus, recipes, mise en place, and inventory requirements: Winter Menu 2024, Harris Foundation Event August 1992, Summer Bar Menu 2003, etc. 

The Test

My test is not meant to be a laboratory quality scientific study. I used the veery accurate digital scale I own at home, and eggs sourced from the corner minimart. I tried carefully to crack and separate the eggs by hand, much like would be done in a real world kitchen. The test is a real world test, and the results reflect the sort of errors and processing mistakes common in kitchens when separating eggs. No doubt that aquacalc.com does a very much more rigorous volume to weight conversion test than can be done at home, but cooks cook in kitchens not in labs; errors, distractions, losses occur.

I wanted to know what size egg in Thailand corresponds to the USDA size Large egg. I suspected this would be the Thai number 2 egg, but I never buy that size, so I decided to do some tests. Would the actual gram weight yield of “1 egg”, or by extension some volume of egg be the same as reported by aquacalc.com? 

I wanted to know what is the meaning, so to speak, of such ingredient quantity specifications as “1 egg” or “1 cup eggs”, or of egg yolk or egg white. The Kitchen Formula Calculator has a built-in re-scaling table that only works using numerical values. You cannot type in “1 egg”, or 2 tablespoons of something. The re-scaling table requires a weight in grams (ounces are possible, but sub-optimal) of the ingredients.

My recipe transcription project is an ongoing thing that is far too much work to manage working out all the ingredient volume to weight conversions in one go. In order to rewrite those old pastry shop recipes using only metric weight ingredient quantity specifications I had long ago started to set up a chart of ingredient conversions by doing my own tests of such stuff as 1 tablespoon of minced ginger = x grams of ginger. Keep in my that an inventory list of food products at restaurants I led might have 600 items listed. So, I referenced both the King Arthur website, and the aquacalc.com site in addition to my own conversion tests. Regarding eggs, both of those sites reference eggs as the USDA size Large egg. How does the data they report correspond to eggs here in Thailand? 

Accuracy for all volume to weight conversions is fraught for reasons I’ve posted on this blog previously, but mainly due to the changing value for density of the ingredients being measured. Ultimately, all converted values in the www.aquacalc.com database (which is the best reference I’ve found) are just very good estimates, reliable enough for rendering food formulations accurately…good enough for government work, as the saying goes. But the important lesson is such efforts as aquacalc.com and others have had to make regarding volume to weight measure conversions ceases to be a way to spend your time once you start writing recipes that reference weights, not spoonfuls.=

Test Results

Bear in mind that both the USDA, and the Thai egg weight standards are for shell eggs. I purchased five each of Thai number 0, and Thai number 1, weighed them individually in shell, and after separating the eggs, weighed the yolks, whites, and shells individually. 

• The number 0 shell eggs I purchased ranged in weight from 69 grams to 71.6 grams. 
• The average egg weight was 70.2 grams (consistent with the Thai standard of >70g). 
• The average usable liquid egg was 59.3 grams. 
• Average shell weight was 8.5g, and average loss from handling was 1.8g. 
• On the basis of this small test, the usable liquid egg weight of a Thai number 0 egg can be said to be 59.3 grams, rounded to 59g.

I repeated the test on the number 1 shell eggs. 

• The number 1 shell eggs I purchased ranged in weight from 64 grams to 68 grams. 
• The average weight of the the number 1 eggs was 64.6 grams. Again, very much consistent with the Thai standard for size 1 eggs >60-65g.
• Average usable liquid egg weight was 54 grams. 
• Average shell weight was 8.6 grams, and average loss from handling was 1.9 grams. 
• On the basis of this test, the usable liquid egg weight of a Thai number 1 egg is 54 grams. 

I repeated the test on the number 2 shell eggs. Since I suspected the Thai number 2 egg is the one to use in my recipe conversions, I bought 15 of these to make it a better sampling. For American readers, keep in mind that a difference of 1 gram is a very small matter. There are 28.35 grams per ounce. The results below show a maximum variation of 4 grams from the smallest of the 15 to the largest. Four grams is less than 1/7th of an ounce.

• The number 2 shell eggs I purchased ranged from 59.1 grams to 63.1 grams.             3 eggs ranged from 59.1-59.5 g;  3 eggs ranged from 60.5-60.9 g;  4 eggs ranged from 61-61.9 g;  3 eggs ranged from 62-62.6 g;  2 eggs weighed 63.1 g
• The average egg weight was 61.2g, consistent with the Thai standard for number 2 eggs of >60-65 grams. 
• The average usable liquid egg weight of the 15 eggs was 50.3 grams. 
• The average shell weight was 7.3g, and average loss from handling was 2.6 grams.
• On the basis of this test, the usable egg weight of a Thai number 2 egg is 50.3 grams. Rounded down to 50 grams, it is precisely the same as the USDA size Large egg. 

To get a direct comparison of USDA size Large vs the Thai number 2 egg one needs to figure out the weight of the Thai egg per dozen since that's how the USDA does things. Therefore, using the tested average shell egg weight of a Thai number 2 egg, 61.2 grams, and 28.35 grams per ounce yields the following: 

                        61.2 grams x 12 = 734.4 grams, and 734.4 ÷ 28.35 = 25.9oz. 

My tested weight results in 25.9 ounces per dozen; very slightly heavier than the 24 ounce USDA size Large weight per dozen. It's likely if more eggs are sampled and the act of separating the eggs is performed more scrupulously, then this 1.9 gram difference disappears. In any case, 1.9 grams is scant difference. 

If the same calculations are made for the USDA size Jumbo and size Large eggs compared to the Thai number 0 and number 1 eggs, the results are very similar; almost identical. It is clear that the Thai Agricultural Standard has simply replicated the USDA standard. The only difference is using a numerical system instead of the dimensional qualifiers, and the very small differences in weights per dozen are due to shifting from ounces (which are not very small measures by comparison) to grams. A USDA size Large egg is a Thai number 2 egg. 

Conclusion 

For the purposes of my transcription project, and to answer the question what does “1 egg” mean, 1 egg means a Thai number 2 egg. “1 egg” also means 50 grams. Whether I buy number 0, number 1, or number 2 eggs makes no practical difference for the small batch recipes I make at home, and since the meaning of “1 egg” is 50 grams I can crack any size egg or eggs, and measure out 50 grams. The only practical procedural difference is I am measuring 50 grams of egg on a digital scale. 

Since the Thai number 2 egg standard is virtually identical to the USD size Large egg, the 50 gram value for “1 egg” applies just as well in American kitchens. Aquacalc.com says so, and so does The Unabaker.