Balsam is the resin that leaks out of trees when they are cut. Several plants with a fragrant resin are referred to as balsam. Balsam, oak, mulberry, and terebinth are not even superficially similar and are unrelated.

Resin was added to wine, as we learn from ancient writers, as a preservative and for medical benefits. It was even used to coat the interior of ceramic vessels, so the wine would not seep out. The Greek historian Plutarch (±46-120 C.E.) observed that resin was used to enhance the bouquet; it improved the taste of wine by Greeks on Euboea, Italians along the Po River and vintners around Vienne in the Rhône Valley.

Pliny the Elder, the famous 1st century C.E. Roman scientist, devoted a good part of one of his books ("Natural History") to the problem of preventing wine from turning to vinegar. Tree resins - pine, cedar, and often terebinth (which Pliny described as the "best and most elegant" resin) - were added to Roman wines for just this purpose. Roman also used resins for medicinal purposes; indeed, modern chemical investigations have proven that resins can kill certain bacteria, thereby protecting organic compounds from degradation.

Analyses of residues in wine amphorae from ancient shipwrecks and storage jars excavated on land have made it possible in recent years to trace the trade and consumption of resinated wines through antiquity to the dawn of winemaking in the Neolithic Near East. The earliest evidence, reported in 1997 by Patrick McGovern and his colleagues at the University of Pennsylvania, comes from Hajji Firuz Tepe in Iran, where wine mixed with terebinth resin was stored in vessels dating to between 5.400 and 5.000 B.C.E.
Hajji Firuz Tepe is a tell, or settlement mound, an archaeological site located in West Azarbaijan province in northwestern Iran. Excavations revealed a Neolithic village that was occupied in the second half of the sixth millennium B.C.E. where some of the oldest archaeological evidence of grape-based wine was discovered in the form of organic residue in a pottery jar.
The plain in which Hajji Firuz Tepe is located lies in the northwestern part of the Zagros Mountains at an elevation of 1,300–1,350 metres. The Gadar River flows through it toward the east to eventually end in marshes bordering Lake Urmia.
The Gadar River valley falls within both the modern and ancient distribution zones of the wild grape (Vitis vinifera subsp. sylvestris) and of the terebinth.
The evidence for winemaking consisted of six 9-litre jars that were embedded in the floor of what archeologists suspect was a kitchen area in a mudbrick building that was inhabited some time between 5400–5000 B.C.E. Inside was yellowish deposits that chemical analysis showed contained residue of tartaric acid and calcium tartrate. As well, analysis found deposit of resin, identified as from the terebinth tree (Pistacia terebinthus) that grew wild in the area. It is possible that the resin was used as a preservative, in a manner similar to the Greek wine Retsina still being produced today, suggesting that winemaking in Hajji Firuz Tepe was deliberately taking place over 7,000 years ago.
Resin has had a long history of being used as ancient sealant and preservative, even before it became associated with winemaking by the ancient Greeks.
Those of us who drink retsina, therefore, are following one of the oldest winemaking traditions in the world.

Bible resources:

1. Genesis 2:12
   That land’s gold is pure, and the land also has sweet-smelling resins and gemstones.
2. Genesis 37:25
   When they sat down to eat, they looked up and saw a caravan of Ishmaelites coming from Gilead, with camels carrying sweet resin, medicinal resin, and fragrant resin on their way down to Egypt.
3. Genesis 43:11
   Their father Israel said to them, “If it has to be, then do this. Take in your bags some of the land’s choice produce, and bring it down to the man as a gift: a little medicinal resin, a little honey, gum, resin, pistachios, and almonds.
4. Exodus 30:34
   The Lord said to Moses: Take an equal amount of each of these spices: gum resin, onycha, galbanum, and pure frankincense.
5. Numbers 11:7
   The manna was like coriander seed and its color was like resin.