Juice from a grape berry comes from three different zones. The composition of the juice is different in each zone. Working from the inside of the berry out towards the skin, the three zones are: central, intermediate and peripheral.
Crushing a berry (breaking open the skin) releases the free run juice. This is the sweetest juice, with the most nutrients and the least amount of harsh phenolics (tannins.) This juice comes from the intermediate zone …
Question: I don’t recall if bubbles in Riesling are considered a flaw or not. Also, are the bubbles produced as a result of fermentation in the bottle?
Answer: In Riesling, bubbles are not considered to be a flaw, although for most high-end Riesling ($30+) they will naturally be eliminated by bottling later or using a permeable vessel (ie: Alsace). If the wine is to be bottled young and bubbles are not desired, a producer can sparge the wine with a neutral gas to remove them.
In general, bubbles are not considered a flaw for white wine. They are most commonly found in …
Question: How important is it to protect a red wine from oxygen during fermentation?
Answer: Oxygen is a dual edged sword. It can be both detrimental and beneficial to wine.
As long as the must is actively and aggressively fermenting, the CO2 being produced will keep the yeast in an oxygen deprived state (so it will produce alcohol) and protect the must/wine from oxygen ingress. Typically punch downs, pump overs, delestage (if they are going to occur) occur with the highest frequency, and without too much worry, during active fermentation. This is a key bit though …