Yeast is a single-celled living organism that is widely used in baking, brewing, winemaking and other industries.

Yeast

也称为面包师的酵母或酿酒酵母

什么是酵母？

酵母是一种单细胞生物，广泛用于烘焙，酿造，酿酒和其他行业。

酿酒酵母can ferment and metabolize a variety of sugars under anaerobic conditions with preference for glucose, fructose and maltose. As a result, it produces carbon dioxide, ethanol and other organic compounds.1,2In baking, the most common forms used are:

  • Compressed
  • Cream
  • 活性或无活性

起源

Various classes of yeasts can be found in many ecosystems and food processing environments. They can be isolated from the nectar of flowers, skins of fruits, honey, surfaces of leaves and plants. In addition, they occur in the soil or can be found in the air.

功能

This ingredient serves many functions in bakery products. However, the two most pronounced ones are:3,4

  1. Dough rising:Carbon dioxide production, which essential for dough rising to build bread volume and improve crumb grain and overall texture.
  2. 面团成熟和风味开发：乙醇和少量有机化合物的产生，例如酮和醛。这是为了使面团融化，并为面包提供口味和香气。

Commercial production

Bakers’ yeast comes in a number of different forms, including compressed, dried/granular, cream or liquid, instant, encapsulated and frozen.

Block diagram for the production of Baker’s yeast

Manufacturers are developing strains that can tolerate and thrive in certain environments. Also, they can perform additional functions that are beneficial to bakers. Here are some examples:

  • 丙酸钙耐受性
  • Freeze-tolerant
  • Osmotolerant
  • 高的vitamin D
  • 麦芽糖酶negative
  • Antimicrobial
  • Acrylamide-reducing
  • Aromatic

应用

酵母是根据满足面包店需求的能力，烘烤面包，面团系统，加工条件和设备的能力选择的。评估该成分的适用性基于：

  • Gassing power
  • Vitality
  • 保质期
  • Form (dry or liquid)
  • Operational conditions at bakery

Forms used in bakeries:

Form 含水量 （％） 固体内容*（％） 处理和应用
Compressed 70.0 30.0
  • 保质期: 2–3 weeks at refrigeration temperature
  • Can be added directly to mixer
  • 应用: medium-sized and high-speed bakeries
  • 活动：尽管比奶油酵母低，但高
Cream 85.0 15.0
  • 保质期: 2–3 weeks under refrigeration
  • Requires storage in agitated tanks. It can be pumped directly to mixer by a bulk ingredient handling system
  • 应用: high-speed bakeries, easiest and most accurate scaling
  • 活动：最高，不容易发生性能的变化
Active dry (ADY) 5.0 95.0
  • 保质期：1年真空（无氧）包装
  • Must be activated in warm water for 5–10 minutes before adding to dough
  • 应用: retail bake shops, in-store bakeries
  • 活动：最低
Instant dry (IDY) 5.0 95.0
  • 保质期: 1 year at vacuum packaging
  • Can be added directly to mixer without activation
  • 应用: retail bake shops, medium-sized bakeries
  • 活动：高于ADY，但低于压缩

*固体包括蛋白质，碳水化合物，细胞脂质，矿物质和维生素

酵母活动或性能is controlled by the following factors:

  • pH: Yeast performs well in a pH range of 5 to 7.
  • Food supply: Simple sugars in bread doughs are provided by flour, amylase activity, or added as part of formulation.
  • Temperature: Yeast is most active at 104–122°F (40–50°C) and is inactivated at 140°F (60°C).
  • 水含量或面团水合。
  • 渗透压：盐和糖会增加渗透压，从而减慢酵母活性。
  • 时间：酵母需要足够的时间来发酵碳源。

FDA regulation

Baker’s yeast is a natural ingredient that can be added to food products with no limitations other than GMPs. Its dried forms are considered GRAS by the FDA.

The agency regulates that commercial yeast has the proper viable microbial content, and complies with food safety standards such as absence of pathogenic bacteria including Salmonella and E. coli, other recognized microbial pathogens or any harmful microbial toxins.5

参考

  1. Hutkins, R.W. “Bread.” Microbiology and Technology of Fermented Foods, 2nd Edition, IFT Press and Wiley Blackwell, John Wiley & Sons, Inc, 2019, pp. 301–342.
  2. Poitrenaud, B. “Yeast.” Handbook of Food Science, Technology and Engineering, Volume 2, CRC Press, Taylor & Francis Group, LLC, 2006, pp. 69-1–69-18.
  3. Rández-Gil, F., et al. “Yeast.” Bakery Products Science and Technology, 2nd Edition, John Wiley & Sons, Ltd, 2014, pp. 153–174.
  4. Cauvain，S.P。“功能成分”。面包制作技术，第三版，施普林格国际出版瑞士，2015年，第84-95页。
  5. U.S. Food and Drug Administration, CFR – Code of Federal Regulations Title 21, Part 184: Direct Food Substances Affirmed As Generally Recognized As Safe,https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=101.100。2019年5月30日访问。