What is “Heat Summation?”

Posted: May 28, 2017

What is “Heat Summation?”

A grape requires a set ‘volume ‘of heat to develop. In a cooler climate the total ‘heat summation’ could take six weeks longer to become ready for picking compared to the same grape variety grown in a warmer climate.  The speed of growth has a huge effect on the grape. The flavour of wine produced from a slowly developed grape will be fine, elegant, lighter bodied, intensely fruity and have higher retained natural acid.  The flavour of the same grape grown in a hot climate that develops quicker produces a wine that is robust, juicy, powerful, full bodied and with a simpler flavour profile.  These grapes often reach sugar maturity before they have time to develop the more complex aroma and flavour compounds achieved with slower maturity. To develop these flavours further, the winemaker often chooses to leave the grape on the vine longer – producing a higher sugar level and ultimately a higher alcohol level.

This is the reason high altitudes and cooler climates generally produce finer style wines like elegant white varietals and pinot noir. These areas include Orange, Adelaide Hills and the Yarra Valley.

These locations are often too cool to produce high quality heavier style red wines, which prefer hotter dryer climes to ripen the fruit – areas like Barossa Valley, Heathcote and Margaret River.  In fact, varieties that have the highest ‘heat summation’ like Cabernet Sauvignon will not ripen at all in some of the cooler climate regions.

Give lighter bodied Shiraz a try!

Over time, we will take you for a journey through every wine region of Australia. Through this, you will get an increased understanding of the different taste profiles and ‘weights’ of wines produced in different terroir and climates. In this subscription we have included some beautiful lighter weight Shiraz from the cooler climates. Try these with your next Sunday roast – lighter bodied wines with lower alcohol are easier on your stomach, will not make you as tired and are just so easy to drink – particularly on a warm day.  ‘Big’ style Shiraz maybe best left for a cold day, by the fire with a big juicy steak. Give these lighter fresher styles a try – and just enjoy the journey!

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