It sounds like you’re doing a lot of things right to optimize aromas in what should be “aromatic” white varieties. I would recommend you make sure your full process includes the following (some of which you describe that you’re already doing):
Pick/harvest cool
Pick at night or in the early morning if you can. Cool grapes retain their aromatic compounds better upon pressing than warm grapes do. Warmer grapes also tend to grow spoilage organisms more readily, which can easily lead to “funky” aromas in all stages of the winemaking process from pressing to fermenting to aging. If you want to maintain the purity of your natural grape aromas, avoid inviting too many unwanted microbial friends to the party.
Keep the pH below 3.5
I’ve had the best luck maintaining aromatic freshness when grapes and juices have a pH of about 3.20–3.50. This is somewhat related to the temperature point I make above, because higher pH encourages what could be unwanted spoilage organisms and their unwanted aroma byproducts. Higher pHs can also lead to higher VA (volatile acidity), another wine flaw when in concentrations higher than around
0.5 g/L.
Pitch an aroma-enhancing yeast
Many commercial wine supply houses (Laffort, Scott Labs, AEB, BSG, etc.) sell lots of yeast strains that claim to enhance aromas. Some interesting cultures are actually mixes of Saccharomyces cerevisiae and non-cerevisiae strains. Your choice of Steinberger seems like a good one, but there may be others you want to try. I love VL3 for Sauvignon Blanc and have been known to pitch CY3079 for Riesling and Gewürztraminer.
Ferment in glass or stainless steel
These are clean, inert containers that don’t contribute any of their own character to a fermentation, unlike oak barrels. Even if an oak barrel is “neutral” it can still allow oxygen into the system, which doesn’t help. The nooks and crannies of barrels are also great insulators and won’t cool off as readily as glass or stainless steel, making fermentations more difficult to keep control of.
Ferment cool (50–55 °F/10–13 °C)
A white fermentation much over 60 °F (15 °C) risks losing some brightness. As an example, fresh pear aromas may end up smelling like “cooked pear” as opposed to fresh and bright aromas of pear. It’s hard to describe, but once you’ve smelled enough fermentations over the years like I have, you’ll understand that even a 10 °F (5 °C) difference in fermentation temperature can make a big difference. Another way to think about it is like a rapidly boiling pot rather than a low simmer. A rapid boil (higher temperature) means that you’re volatilizing off many more aromatic compounds into the air rather than keeping them in your fermentation where they belong.
Try enzymes
Most winemaking supply companies sell enzymes that can be added to must in the press, in the pre-settling juice phase, or in settled and racked juices. Some, like Betaglycosidase enzymes, can even (and in fact must) be used after fermentation because they’re inhibited by high sugar levels. These specialty enzymes can cleave terpenes and norisoprenoids off into the finished wine and release them into the “free” state so they’ll be available as aromatics in the wines. Enzymes can be sold in liquid or powdered form and are extremely useful in breaking down skins so that the maximum amount of aromatic compounds are released into the juice. Pectinases are great added to the crushed fruit or directly in the press as a skin-contact enzyme. They break down skins and pectin, allowing more aromatic compounds to be extracted during pressing. Beta-glycosidase enzymes act upon bound aroma compounds, converting them into the “free” form. Whichever enzyme you choose, it’s always good to follow instructions and to use recommended amounts. Where possible, do bench trials first to see if you like the results!
