Yeast performance testing encompasses various procedures for determining either the time required for dough to reach a certain volume or the volume of dough at a given proof time.

酵母表现测试

Also known as yeast activity or gassing power

What is Yeast Performance Testing?

Yeast performance testing encompasses various procedures for determining the time required for dough to reach a certain volume, or the volume of dough at a given proof time. This can be evaluated using standardized procedures.

Yeast performance tests allow bakers to:

  • Adjust yeast levels in dough for optimum volume
  • 在发酵和打样期间预测酵母表现
  • Adjust proofing/fermentation conditions like temperature or humidity
  • Adjust formulation and evaluate the effects of sucrose, water and salt on yeast activity
  • Evaluate the impact of freezing/thawing on yeast tolerance
  • Detect excessive or insufficient levels of starch damage and/or α-amylase activity

它是如何工作的？

Yeast performance tests assess the production of CO2 gas during the发酵or打样of a dough sample under standardized formulation, temperature and humidity conditions. The Cereals & Grains Association (AACC International) provides a method for assessing the activity (gas production) of yeast in dough. The method determines:

  • Total or cumulative gas production during a fixed time at a controlled temperature, expressed in mL, or any other equivalent unit such as gauge pressure on a sealed container
  • 在标准气压下，气体生产率（毫升气体也在每分钟进化）。

The method is applicable to the following yeast forms:

  • 压缩酵母(CY) with approximately 30% solids
  • 活性干酵母(ADY) with approximately 92% solids
  • Instant dry yeast (IDY) with approximately 95% solids

Formulas containing 0, 8, and 20% sugar (based on flour weight) can be used for different tests. Dough formulations must be prepared so that equal weights of dough contain equal weights of yeast solids (0.70 g of yeast solids per 100 g of dough). The higher the sugar level, the lower the yeast activity.

应用程序

The yeast performance test using the AACCI Official Method 89-01.01 below is for compressed and active dry yeasts:1

  • Pretreatment of yeast
    • For CY: 5 min before mixing, weigh 0.01 g of compressed yeast, crumble it into a beaker and soak in distilled water at 70°F (21°C) for yeast rehydration. See formulas in the table below.
    • 对于Ady：在使用前将酵母温热至室温至少30分钟。用水制备3％糖溶液，用于烧杯中的酵母再水合（参见配方）（再水化水为酵母重量的4-5倍）。然后，重量为0.01g干酵母，加入糖溶液，初始轻度搅拌。在110°F（43℃）下再水化10分钟，充分搅拌以获得酵母的均匀悬浮液。
  • Mixing of dough
    • 重量除酵母外，除了酵母和放入搅拌机碗中。面团温度可在86±2°F（30±1°C）。
    • Add yeast suspension to mixer bowl. Use the rest of water for dough hydration to rinse in yeast (see formulations). Mix dough in a pin mixer to full development and to 86 ± 2°F (30 ± 1°C).
    • Give dough 5-min bench rest while measuring temperature.
  • Determination of gas production
    • Any instrument for measuring pressure or volume of gas evolved during dough fermentation can be used.
    • 将面团件（适当的尺寸）放入燃气测量装置的每个腔室中。允许5分钟的温度平衡。然后在86±2°F（30±1°C）时开始气体测量。水浴可用于保持恒定的面团温度。
    • Measure gas evolution over 90-min period.
    • 报告每小时总量的总量（90分钟后进化）。如果使用压力单元，则必须使用完美的气体法则将值转换为标准气压的气体体积。

Dough formulas for compressed and active dry yeast

Ingredient 0.% Sugar 8.% Sugar 20％糖
CY. ad CY. ad CY. ad
Bread flour 10.0. 10.0. 10.0. 10.0. 10.0. 10.0.
糖（蔗糖，精制，结晶） - - 8. 8. 20. 20.
Nonfat dry milk - - 4. 4. 4. 4.
Shortening 3. 3. 3. 3. 3. 3.
盐 2 2 2 2 2 2
水（蒸馏用于酵母再水水） 25 6.25 25 6.25 25 6.25
Water, remainder 4.0. 60 3.8.。75 58.75. 28.。75 48.75
Yeast, wet weight 4.。0.6 1.31 4.。3.2 1。4.0. 4.。3.7 1。4.1
Or, yeast solids 1.218 1.205. 1。296 1。28.8. 1.310 1。297
Total weight of dough (Baker’s %) 174.06 172.56 18.5.07 18.3.。4.0. 18.7.12 18.5.41
Weight of yeast solids/dough, % 0.。70 0.。70 0.。70 0.。70 0.。70 0.。70

Instruments/equipment used for testing yeast performance

  • Risograph
  • Fermentograph
  • Maturograph
  • Rheofermentometer
  • GAROBARM.

Relevant considerations

  • All formulations are based on 100 g of flour. However, amounts can be scaled up or down depending on the test needs. Formulas must always contain 0.70 g of yeast solids per 100 g of dough. This allows comparison of gassing power among different yeast types.
  • Yeast performance and baking quality: Gas production and retention by the dough are directly related to the quality of the finished products. Loaf volume and crumb grain are dependent on yeast activity and gas retention in the gluten matrix.

References

  1. AACC International. Approved Methods of Analysis, 11th Ed. Method 89–01. Yeast Activity, Gas Production. Final approval October 26, 1994; Reapproval November 3, 1999. Cereals & Grains Association, St. Paul, MN, U.S.A.