How much does homemade mayo differ from store-bought mayo? By Julie Jones

Data whole-heartedly substantiate Dr. Carlos Monteiro’s statement that the obese are at greater risk of contracting COVID-19 and that it increases the risk for more severe illness. Obesity is a factor in other chronic conditions such as type 2 diabetes and heart disease, which also increase COVID risk.  All of these underlying conditions create a state of chronic inflammation. Thus, an already overtaxed immune system is less well able to fight the virus.

This month the site is focused on the NOVA classification of food, championed by Dr. Carlos Monteiro. An earlier post on the site referred to comments he made in a TV interview in Brazil. Julie Jones has been an invited speaker both in the country and around the world pointing out flaws in the concept of ultra-processed foods. She has served as a guest on this site praising processed food and pushing back on warnings about emulsifiers in food. Today she responds to some of Monteiro’s claims and provides some insight into the similarities of homemade and store-bought mayo.

According to the Dietary Guidelines Advisory Committee Report released in the summer, 70 percent of Americans are overweight or obese.  Further, 6 in 10 Americans have one chronic condition and 4 in 10 Americans have 2 or more. No one disputes that poor lifestyle and diet choices contribute to these sobering statistics.  Sadly only 3-8 % of Americans eat according to recommended patterns such as USDA MyPlate or the DASH diet.

I, however, dispute the conclusion that ultra-processed food (UPF) is the cause or avoidance of will help fight COVID. Perhaps, if the term ‘ultraprocessed’ were ‘code’ for foods that are both nutrient poor and calorie dense such as sugar-sweetened beverages, candies, and salty doodles, then I might agree. While the aforementioned UPFs are flagged by dietary guidance worldwide as foods ‘to limit’, under the NOVA classification a number of foods deemed as UPFs are ones that should be chosen if eaten in recommended quantities or under certain circumstances such as infant formula where medical or other extenuating conditions prevent nursing.

Monteiro cites data that diets high in UPFs are related to obesity, heart disease, even some types of cancer and diabetes. These data are from the very same epidemiological cohorts that associate diets of poor quality or high in sugar-sweetened beverages with increased risk for these diseases.  The actual cause is more likely limited intake of recommended foods that populate traditional dietary guidance, eg. not the right number of servings of fruits and vegetables, not the right mix of fruits and vegetables and enriched and whole grains, excessive portions of high-fat meats, and no attention to calories or portion size. Thus, it is about poor consumer choices rather than UPFs.

Having consumers focus on preparing foods, while a noble goal with the potential of improved taste and other advantages such as interest in food etc,, it  may not improve fiber or nutrient intakes, increase the number of servings of legumes, fruits and vegetables, lower calorie intake or spur greater physical activity. The avoidance of UPFs such as commercial breads and cereals especially whole grain ones, prepared vegetable items, flavored milks, to name a few may actually not improve nutrition or health.  Data show that removal of flavored milks from the school feeding programs decreased milk consumption and lowered calcium intake.

Avoidance of commercial breads and cereals will dramatically lower whole grain and dietary fiber intake – both of which are far from recommended levels since under 5% meet either the fiber or whole grain intake.  Half of the fiber intake is from the breads and cereals group, and minimally processed grain foods make up under 5% of the total grain intake.  Reliance on minimally processed grain foods for fiber and whole grains would require a seismic dietary shift. Shifts to home baking of breads require a minimum of 3 hours from a day – a time luxury many single mothers or working families can’t provide.

Monteiro also notes that UPFs have little in common with their home-prepared counterpart.  He states that homemade mayonnaise and UPF mayonnaise are two completely different things. This example explores the validity of that statement. 

Recipes for home-prepared mayonnaise contain the following: egg, oil, vinegars or acid juices, salt, spices and flavorings. Commercially produced mayonnaise has a standard of identity, and it has the same ingredients. Its formulation (like many commercial products) is codified in FDA’s CFR – Code of Federal Regulations Title 21 as follows:

bottle of real mayonnaise
Store-bought mayonnaise

“(a) Description. Mayonnaise is the emulsified semisolid food prepared from vegetable oil(s), one or both of the acidifying ingredients specified in paragraph (b) of this section, and one or more of the egg yolk-containing ingredients specified in paragraph (c) of this section. One or more of the ingredients specified in paragraph (d) of this section may also be used. The vegetable oil(s) used may contain an optional crystallization inhibitor as specified in paragraph (d)(7) of this section. All the ingredients from which the food is fabricated shall be safe and suitable. Mayonnaise contains not less than 65 percent by weight of vegetable oil. Mayonnaise may be mixed and packed in an atmosphere in which air is replaced in whole or in part by carbon dioxide or nitrogen. [See details at the end of the article]*

So, let’s compare commercial mayonnaise and homemade mayonnaise by first comparing ingredients and processing.

Eggs– Commercial mayonnaise is formulated with some form of pasteurized egg products. Pasteurization kills pathogens such as E. coli, Staphylococcus, and Salmonella.

USDA recommends pasteurized, liquid eggs or ‘in-shell pasteurized’ eggs in homemade mayonnaise and warns against the use raw eggs. If pasteurized eggs are unavailable, eggs used in mayonnaise should be cooked with continuous stirring in a pan atop a simmering water bath to 65oC or 150oF to kill any bacteria.

Acids – Both commercial and homemade mayonnaise use vinegars and other acidic juices such as lemon juice.  While both may contain a variety of acid ingredients, commercial mayonnaises must meet the FDA standard for total acidity and amount of acetic acid. The acidity specification creates the high acid environment that, together with pasteurized eggs and sterile technique, maintains the safety of commercial mayonnaise.

Flavors – Both can have a nutritive carbohydrate sweetener. This is usually sugar but could be other sweeteners.  Both usually have salt, spices and herbs, and flavorings. All these ingredients not only add flavor but can inhibit microbial growth.

Shelf Life – Homemade mayonnaise that is unused should be refrigerated and kept only a few days. Even if prepared with pasteurized eggs, bacteria or other components potentially present in herbs and spices or on preparation blades or containers may contaminate the mayonnaise.  Commercial mayonnaise has been pasteurized during processing. Once it has been opened,  refrigerated promptly after use, and not cross-contaminated during use, it should be safe for several months.

Food additives –Citric, malic and acetic acids are considered ‘additives.’  Citric acid, the main acid in lemon juice and malic acid, found in apples and stone fruits, grapes and berries are used to achieve acidity and various flavor profiles of commercial mayonnaise. In like manner, gourmet cooks preparing flavored mayonnaise use a variety of vinegars and acidic juices.

Two other types of additives are used.  One category is sequestrants such as EDTA, which holds the iron from egg yolk to prevent it oxidizing the fat or discoloring the mayonnaise during storage.  Another is fat crystallization inhibitors, which are added to prevent oil in the mayonnaise from solidifying and destabilizing the emulsion if the product experiences low temperature during shipping. Crystallization inhibitors such as lecithin or oxystearin are fatty materials that also function as emulsifiers.  Egg yolk and soy are common sources for lecithin and various food fats for oxystearin. Both are considered to be very safe by regulatory bodies such as the WHO Joint Expert Committee on Food Additives. 

This lengthy discussion about mayonnaise was an attempt to debunk statements that UPFs such as mayonnaise vary significantly from homemade in either ingredients or nutrition. Ironically, UPF mayonnaise would, in most cases, be the safer choice for all, but especially for pregnant women and the immunocompromised.

In terms of storage, convenience and cost. The commercial product is more convenient and lasts much longer. Ingredient costs for homemade are approximately $0.27 per ounce with pasteurized eggs, but this is quite variable because the prices of oils, vinegars and eggs. The nationwide average for commercial is $0.39/ ounce. If time is considered at $ 7.25 /hour for minimum wage, and 20 minutes time for preparation and cleanup (without heating the egg), the cost is ~$.0.70 per ounce.

So, are UPF and homemade mayonnaises the same?  The ingredients and nutrition are, but the cost, effort, convenience, sustainability and safety can be quite different. 

Next Week: NOVA as seen by a cook and a food scientist

back of the mayo jar
Mayo label

*(b) Acidifying ingredients. (1) Any vinegar or any vinegar diluted with water to an acidity, calculated as acetic acid, of not less than 2 1/2 percent by weight, or any such vinegar or diluted vinegar mixed with an optional acidifying ingredient as specified in paragraph (d)(6) of this section. For the purpose of this paragraph, any blend of two or more vinegars is considered to be a vinegar. (2) Lemon juice and/or lime juice in any appropriate form, which may be diluted with water to an acidity, calculated as citric acid, of not less than 2 1/2 percent by weight.

(c) Egg yolk-containing ingredients. Liquid egg yolks, frozen egg yolks, dried egg yolks, liquid whole eggs, frozen whole eggs, dried whole eggs, or any one or more of the foregoing ingredients listed in this paragraph with liquid egg white or frozen egg white.

(d) Other optional ingredients. The following optional ingredients may also be used: (1) Salt. (2) Nutritive carbohydrate sweeteners. (3) Any spice (except saffron or turmeric) or natural flavoring, provided it does not impart to the mayonnaise a color simulating the color imparted by egg yolk. (4) Monosodium glutamate. (5) Sequestrant(s), including but not limited to calcium disodium EDTA (calcium disodium ethylenediamine- tetraacetate) and/or disodium EDTA (disodium ethylenediaminetetraacetate), may be used to preserve color and/or flavor. (6) Citric and/or malic acid in an amount not greater than 25 percent of the weight of the acids of the vinegar or diluted vinegar, calculated as acetic acid.

[42 FR 14481, Mar. 15, 1977, as amended at 57 FR 34246, Aug. 4, 1992; 58 FR 2886, Jan. 6, 1993]”….

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