Beginner perfumer · 89
Of the 145 records told to refrigerate, 13.8% are carboxylic acids. Among the other records with storage conditions, it is 1.5%
· 11 min read
Last time I found that the storage field holds only four strings across the whole database, and that its strongest instruction — refrigerate — lands on 145 records. This time I went to see what those 145 are. They are not the most volatile: the refrigerate group's median boiling point is 229°C against 214°C for the rest. The real difference is chemical class. Records whose name ends in 'acid' make up 13.8% of the refrigerate group and 1.5% of the others — 9.4 times over. Sulfur compounds run 4.8% against 1.3%. And the other half of the story is that these 145 records are barely fragrance materials at all: 35.2% have 'fragrance' in the category field, against 79.7% for the rest.
About a 4 minute read.
Last time I found that the storage field holds only four strings across the whole database, and that the strongest of them — refrigerate in tightly sealed containers — lands on 145 records.
This time I went to see what those 145 actually are.
Ruling out the obvious explanation first
I assumed refrigeration goes to the most volatile things. It does not.
| Refrigerate (145) | Other storage records (1,087) | |
|---|---|---|
| Median boiling point | 229 °C | 214 °C |
| Median molecular weight | 192.3 | 178.2 |
The refrigerate group boils higher and is heavier. If refrigeration were about holding volatiles down, this runs the wrong way.
The real difference is chemical class
Sorting both groups' names crudely by suffix — a blunt method, but the same ruler applied to both:
| Class | Refrigerate | Other | Ratio |
|---|---|---|---|
| Carboxylic acids | 13.8% | 1.5% | 9.4× |
| Sulfur compounds | 4.8% | 1.3% | 3.8× |
| Lactones | 1.4% | 1.0% | 1.4× |
| Esters | 22.8% | 25.5% | 0.9× |
| Aldehydes | 5.5% | 7.3% | 0.8× |
Acids are 9.4× enriched. I recomputed that one strictly — names ending in "acid": 20 records (13.8%) in the refrigerate group, 16 (1.5%) among the rest. Same conclusion.
The best-supplied acids in the refrigerate group:
| Suppliers | Material | Odour type |
|---|---|---|
| 82 | 2-methyl butyric acid | acidic |
| 67 | Isovaleric acid | cheesy |
| 53 | Propionic acid | acidic |
| 50 | 2-methyl-2-pentenoic acid | acidic |
| 21 | Linoleic acid | — |
The seven sulfur compounds are easy to spot too: bis(2-methyl-3-furyl) disulfide (43 suppliers, meaty), methional (52, vegetable), that family.
Acids esterify and drift; sulfur oxidises into different sulfur. Refrigeration is suppressing reaction rate, not volatility. Which explains why the higher-boiling group is the one that needs it — their problem is not escaping, it is becoming something else.
But there is another half to the story
I thought that was all of it, until I looked at the category field.
| Refrigerate | Other | |
|---|---|---|
| Category contains "fragrance" | 35.2% | 79.7% |
Two thirds of the refrigerate group are not fragrance materials. Its top categories are flavoring agents (36), flavor and fragrance agents (34), natural substances and extractives (19) — and only 7 pure fragrance agents.
The odour-related fields collapse alongside:
| Field | Refrigerate | Other |
|---|---|---|
| Odour type | 41.4% | 80.8% |
| Strength | 24.1% | 62.6% |
| Substantivity | 16.6% | 59.2% |
"Refrigerate" mostly arrived from the food side. It is the food industry's standard handling for acids and sulfur compounds, and it came into this database attached to flavour records.
So for someone making perfume
The 51 records whose category includes fragrance are the ones to read. And they cluster on the same things — acids and sulfur.
The refrigerate records with 40+ suppliers that really are perfumery materials: geranyl acetate (130), α-ionone (115), γ-decalactone (111), ethyl butyrate (102), acetaldehyde (94), (E)-2-hexenal (91), isovaleric acid (67), β-ionone (78), (E)-β-damascone (41).
The ionones and damascone are in there, and they are neither acids nor sulfur. They are a separate line — conjugated ketones that photo-oxidise. The database gives no reason and I am not going to invent one.
Three lines of practice
- If you own carboxylic acids, chill them. Butyric, isovaleric, propionic, 2-methyl butyric — their drift is a chemical change, and room temperature will not hold it.
- Chill the sulfur compounds too. And fill the bottle when you decant.
- Do not assume a high boiling point means room temperature is fine. The refrigerate group's median boiling point is 15 degrees higher than everyone else's.
What this doesn't establish
- The chemical classification is by name suffix, which is blunt. "Other" is 51.7% of the refrigerate group and I did not sort that pile. I recomputed acids and sulfur strictly; nothing else.
- 9.4× is a descriptive ratio with no statistical test, and I did not control for the confound that the refrigerate group skews toward flavour records — acids are more common in flavour work to begin with, so the two findings are partly the same fact.
- I do not know who made the refrigerate call, or on what basis. The field cites no source.
- I have not explained why ionones and damascone are in the group. Photo-oxidation is my guess; the database does not say.
- I ran no storage experiment. This is field statistics.
- The storage field covers only 1,232 records (2.9%), so this comparison describes those thousand-odd, not the database.