Leavening Yeast: Accounting for Choices
July 01, 2009
by Laurie Gorton
This is not your father’s bakers yeast. Two big changes in this ingredient characterize what’s now available to producers of grain-based foods — not changes in the single-celled organism responsible for fermenting doughs, but in the way it is delivered and in the expanding palette of strain characteristics from which to choose.
“The days of providing a generic ‘off the shelf ’ fermentation solution are long gone,” said Steve Bright, technology manager, AB Mauri Fleischmann’s, Chesterfield, MO.
CREAM OF THE CROP.
In the decade since its introduction, cream yeast now dominates in wholesale production of bread. Dean Modglin, director of sales, wholesale bakeries, Red Star Yeast Co. LLC, Lesaffre Yeast Corp., Milwaukee, WI, estimated that cream yeast accounts for 75% of yeast sold by the company and for good reason. “Cream yeast is consistent,” he said. “Its gassing activity is adjusted at load-out from the manufacturing plant, so it shows increased consistency compared with crumbled or block yeast.
“Cream yeast is a necessity for the big bakers,” Mr. Modglin continued. “It enables them to use a closed-loop ingredient handling system with automatic delivery of the yeast directly to drop points at the mixers.” Sanitation, always a concern with yeast, improves because cream yeast is handled in the bakery by a tank system with automatic clean-in-place capacity, and there are no bags to open and discard.
The huge jump in usage of cream yeast by larger bakers was also noted by Scott Miller, National Yeast, St. Louis, MO. (National Yeast is partnered with Minn-Dak Yeast Co., Wahpeton, ND, and USA Yeast Co., Hattiesburg, MS.) “Most of the automated bakeries now use cream yeast,” Mr. Miller said. “Most are conversions, but nearly every new bread bakery is built with automated ingredient handling capability, and that includes cream yeast.”
“Yeast doesn’t always get its due respect,” Mr. Miller said. He noted a current big push to differentiate bakers yeast products by increasing their value to the customer and gave as examples the highly specific needs for yeasts suitable for frozen dough or high-sugar breads.“Such characteristics are driving the changes in baker yeast products,” he stated.
Mr. Bright reported, “Our customers are becoming more sophisticated and their needs more specialized, and our R&D experts spend a consid- erable amount of time and effort to provide for the bakers’ needs.”
“The proliferation of choices for bakers yeast results mainly from a compromise between the costs (in use) and the benefits of differentiation,” said Jan Van Eijk, PhD, research director, Lallemand, Montreal, QC.
Lean-dough yeast strains, cited by Dr. Van Eijk as an example, perform better t h a n regular b a ke r s yeast in f o r mu l a - tions low in sugar and without mold inhibitors, while high-sugar strains suit high-sugar products that also contain calcium propionate.“Most fresh yeast used in North America is a compromise between lean and sweet dough performance using a single yeast strain,” Dr. Van Eijk observed. Additionally, the company supplies Eagle VitaD bakers yeast, an active yeast that is also a natural source of vitamin D, which he described as “a true nutritional benefit for the baker to provide to the consumer.”
Why are there so many bakers yeast choices? Arnaud Deniaud, director, technical services, Red Star Yeast/Lesaffre, answered, “Bakers started to realize yeast could be adapted to specific applications. The choices now answer needs in terms of formulation and production needs such as osmo- and sugartolerant styles. The stresses on bakers yeast are not the same when viewed in light of the baking formula and process, fresh versus frozen, sugarfree versus high-sugar, preservativefree versus preservative included.”
For example, sugar tolerance is a quality needed in the Hispanic market, particularly for production of sugarrich conchas, the signature bread offered by most panaderias. “You can use regular bakers yeast, but you’ll get more consistent results with a sugartolerant variety,” Mr. Deniaud said.
Flavor plays a role, too. Mary Fitzpatrick, director of sales, bakery and food service, Red Star Yeast Co., said that customers in the fresh pizza market prefer the yeasty flavor contributed by active dry yeast (ADY). Because of the way ADY is made, it contains a percentage of dead yeast cells. “These give the yeasty flavor that is so highly desired by that customer base,” she said.
The newest style is an instant active dry yeast (IADY) with improved gassing powers, SAF-Instant Premium, introduced a few weeks ago. Ms. Fitzpatrick explained that the product is a new strain of bakers yeast that allows the baker to use about 30% less yeast than other IADY products yet achieve proper fermentation and leavening action.
“This yeast has more activity, more gassing power,” Mr. Deniaud added. “With it, we have tried to solve some of the issues with IADY, one of these being sensitivity to cold
water.” In making doughs that will be retarded or refrigerated to make items such as Danishes and croissants, bakers want to use the coldest water possible, opting for ice-cold temperatures. The strain chosen for the new product shows more resistance to cold than regular bakers yeast, including other IADY and active dry yeast forms.
Tolerance of bakers yeast to the presence of mold inhibitors takes on increasing importance. “The baking industry is increasingly raising the bar of shelf-life expectance,” Mr. Bright said. “As a result, we have seen higher levels of preservatives being used, and it is critical that the yeast activity is constant, regardless of preservation levels.”
“Consistency is key,” Mr. Miller stated.“Desired performance level can be customer-specific, but the common thread is consistency.”
“The industry expects consistency,” Mr. Bright said. “This has never been more true than today where tolerance and timing are critical.”
Consistency starts with the manufacturing process, and managers at Lesaffre called attention to a significant change in their company’s methods. “The greatest move to achieving improved consistency from our Red Star products happened when we switched to corn sugar as a pure source of carbohydrates at our Cedar Rapids plant,” Mr. Deniaud said. “Molasses is a raw material that varies a lot. At our other plants, we use a blend of cane, beet and corn sugars, but Cedar Rapids is 100% corn sugar. Because that raw material is very consistent, it allows us to make a consistent product.”
Consistency also refers to how the yeast handles at the bakery, as Dr. Van Eijk observed, noting that compressed yeast must be easily crumbled without being gummy and that all forms of yeast must be easily dissolved in water without leaving grit or producing foam. Other desired characteristics depend on application and include stability in refrigerated storage as well as in dry mixes, expected taste and flavor, cryo-resistance in frozen doughs, dough relaxing effect and nutritional benefit. With so many qualities sought, no wonder there are so many styles of bakers yeast available today.
All yeast suppliers work diligently to assure consistent performance from their products. As Mr. Bright explained, “Globally, we developed a proprietary testing system that allows us to look at the gassing activity under very controlled conditions. Our plants all over the world take part in audits whereby each plant tests a standard sample of flour, yeast, salt and sugar for analysis and comparison.”