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grapegrowing Sugar per berry (mg/berry) The plateau is reached when the speed of sugar loading is ≤ 3 mg/berry/day. The Brix value at the beginning of the plateau is an important criteria. Slope = the speed of sugar loading (mg/berry/day) Ripening Duration of the plateau (number of days after Day 0) allows the scientist to determine the level of ripeness from fresh to mature fruit for the red cultivars. Day 0 Ripeness Over-ripeness Figure 1 — Berry sugar loading concept: This theoretical curve is based on data obtained over five years with at least 20 different grape varieties in different countries, principally France, Spain, Argentina and Chile. This curve has been recently calibrated for some South African viticulture areas and cultivars (in collaboration with Distell). Please take into consideration that this calculation is only an approximation of sugar loading into berries. This is due to many reasons, among others: seed volume and number, sugar distribution between skin and pulp. Despite the calculation being an approximation with shortcomings, it nevertheless is a useful indicator, and its use is becoming more common. NEW Practical Winery Library! Single-subject articles on a wide range of topics Profiles of sugar loading It is possible to distinguish three principal sugar loading profiles: 1. Continual and rapid loading — This type of sugar loading occurs from véraison and is related to the active functioning of carbon production sources (leaves) that supply plant sinks (berries, secondary shoots etc.) during their growth phases. It is therefore often associated with significant vegetative growth and greater berry volume. Phenolic maturity is not affected. This type of loading is often considered beneficial for production of rosé, fresh fruity red wines or pleasant aromatic white wines. 2. Slow sugar loading/inhibition of ripening — Low sugar content per berry, associated with a slow loading rate, can be considered to "block" ripening, and this could be indicative of vine imbalance. If major physiological problems such as mineral deficiencies, viral diseases, etc., are excluded, blocked ripening can often be related to excessive water deficit, heat waves or an excessive crop load in relation to the exposed leaf surface.5 In all grape varieties, this type of situation is far from ideal in terms of standard vinification practices in white and dry red wine production. Furthermore, in relation to red and black grapes, this situation may be associated with blocked technological and phenolic maturities. Ultimately, it may be necessary to adapt the fermentation procedure to this type of grape, with thermovinification and short maceration with limited extraction being preferred options. Don't scrape the bottom of the barrel From the archives of Practical Winery & Vineyard Choose the best wine testing available from Randox Food Diagnostics • 170 Wine tests per hour • Improved eflciency • Reduced costs • Reduced cost per test • Easy to Use • 1 Calibration per harvest Wine Testing Kits Available Acetic Acid • Ammonia • Copper • Ethanol • Glucose/Fructose • Iron • Lactic Acid Malic Acid • Potassium • Total Antioxidant Status • Total S02 PracticalWineryLibrary.com FOOD DIAGNOSTICS Randox Food Diagnostics 515 Industrial Boulevard, Kearneysville, West Virginia, 25430 T +1 304 728 2890 F +1 304 728 1890 E enquiries@randoxfooddiagnostics.com I www.randoxfooddiagnostics.com pr actica l win ery & vin eya rd MAY 20 13 59