The science of vinegar. Part 3. Sensory analysis.

Review.

First of all, we needed to develop a comparison mechanism that would allow us to determine whether certain vinegars are worth further study. In this part of our posts on the science of vinegar, we will describe in detail the process of sensory analysis, which included the collection of a trained jury, the creation of taste descriptions, the development of standards and repeated series of tests that we used not only to determine the specific characteristics of vinegar, but also to select the cooking processes that give the most delicious results.

As a result, we came to the conclusion that the taste of vinegar with some residual sugar, passed a greater number of fermentation stages, more intense and interesting.

Although we are trying all the results of our experiments, in the case of this project we decided to use descriptive analysis to compile the exact profile of each vinegar. This would allow us to obtain dry, measurable data for further processing, as well as explore the best ways to incorporate sensory analysis into our research. We conducted a descriptive analysis of our vinegars At the faculty of Natural Sciences of the University of Copenhagen at Frederiksberg. We were assisted by a specially trained jury of ten volunteers from the Department of food Sciences. The purpose of this analysis was to identify specific tastes, to link their descriptions to real reference points and to determine the saturation of each of them.

The key components of a descriptive analysis are:

• Samples in the experiment set: are they similar or different? Small differences can be difficult to isolate, but can provide more accurate and less obvious taste information. Our samples were somewhat similar, they were all vinegars, the differences in flavors which originate from the differences in the basic ingredients.

• Jury: People are analysts who can give an account of the present tastes and their saturation.

-Creation of tools for the description of taste: the Jury also allows you to determine what flavors are present and prevail in a particular set of samples. First, the jury members try the samples blindly, thinking about their perception and discussing it with each other, which leads to:

• Terminology and reference points: for each taste that was recognized by the jury, it was necessary to create a description that fixes the unanimous definition of each flavor. For example, when a jury member says “citrus”, does he mean lemon skin or orange skin? Or something that exists only as a combination of several fruits? We needed to develop an optimal combination that would serve as a single standard and allow to keep all the jury members within a single olfactory dictionary.

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Along with the classic “sweet”, “sour”, “salty”, “bitter” and “minds”, we have narrowed the list of flavors to “red berry”, “strawberry”, “acetic acid”, “rotten fruit”, “chemical”, “green Apple”, “liquorice”, “yeast” wine“,” tropical fruit “rhubarb”, “celery”, “earthy”, “green vegetable”, “citrus”, pine and blue cheese. Finding a common language for some of them was quite simple. Everyone agreed that the descriptor "strawberry" is perfectly represented by ripe strawberries, cut in two. But what about less accurate descriptors? "Rotten fruit", according to our jury, the groin is not completely rotten Apple, and more oxidized and fermented Apple than just beaten.

As a result, we agreed that this flavor is perfectly transferred to the cut into cubes, slightly dented, sprinkled with yeast apples and pears, left on the table for a day. Dry yeast seemed too weak to the jury, while the fresh yeast cube was spot on (the Danes use exactly this type for baking,and apparently it was just better known to our local jury). For the "red berry“, which differs from the” strawberry" jury insisted, neither red currant nor raspberry were not good enough separately, but in combination were satisfactory. The “chemical” flavor that the jury noticed was most likely ethyl acetate, a frequent byproduct of acetic fermentation originating from the reaction of ethyl alcohol and acetic acid; a nail Polish remover came up perfectly for this descriptor. For “pine” and “earthy flavor” I collected the samples in the Assistens cemetery in Nørrebro. Who knows, maybe they even contained a few molecules of Hans Christian Andersen buried there.

When reference samples were agreed and prepared, we started our descriptive analysis.

For three days, our jury members sniffed reference samples to remind themselves of their flavors and corresponding descriptors, and then went to isolated booths, where they in turn tasted vinegar and evaluated the strength of each of the reference flavors in each of them.

Put together an estimation of saturation included the data about the taste profiles that we used for analysis of sensory characteristics of the vinegars. Some statistical techniques we applied to determine which flavors and descriptors are most effective in distinguishing samples from each other, while other techniques we used to look at the data integrally and compare them with odor-active molecules in each of the vinegars to describe sensory and molecular taste engines across the data set.

The sensory and chemical analyses we performed on our vinegars gave us a fresh look at how their taste components interact. By continuing to borrow analytical techniques from academic laboratories studying perception and taste chemistry, we hope to form molecular intuition about tastes, in addition to the intuition of our receptors. However, when it comes to the answers we are looking for and the related questions, the scientific process is limited in its capabilities. To fully understand food, we need to listen to our receptors in a more aesthetic, less measurable way. For example, some of us, as well as members of the jury, discussed differences in balance, complexity and depth of taste, which are difficult to measure analytically. We can develop our culinary empiricism to cope with such ideas faster and better, not only taking into account the dry data that we have available, but also contemplating and making decisions about the most interesting areas, based on our feelings.

Many of the most interesting questions that arose during the development of vinegar, had little to do with naturalistic, analytical ideas about the ins and outs of taste chemistry and more to do with practical concerns about what to do with these ingredients, how to work better with them and how to produce something new, interesting and better than what we already have.

For example, it seemed that the most delicious vinegars — the most complex, passed through a series of fermentation (for example, yeast fermentation, followed by acetic fermentation). At the molecular level, this theory is logical: each stage of fermentation produces more variety of volatile molecules as secondary reaction products, which leads to a larger set of potential flavors. Moreover, if you start with a sweet mixture and ferment it into alcohol with yeast, the residual sugar will partly balance the acid, adding the body and improving the overall taste. At the same time, some vinegar-based teas have an interesting taste potential, but sags in complexity. We were also wondering if the “aerator” approach to vinegar fermentation, which has helped us in particular in the accelerated prototyping of vinegars in less than a week, led to some changes in taste (good or bad) relatively slower, passive fermentation over months.