Milling & Baking News - November 26, 2013 - 21

S P E C I A L E D I T I ON

Nutritional and
Health Beneﬁts
of Yeast
Practical technology from Lallemand Inc.

The Roles of Yeast in Baking, Nutrition, and Health

EAST NOT ONLY leavens dough
and gives it a light, sponge-like texture-yeast also provides ﬂavor and
aroma and contributes to the nutritional
value of bread.
LEAVENING

The carbon dioxide gas produced by yeast
expands the dough as it is trapped within
the dough's protein matrix. This stretching
results in the light, airy structure associated
with yeast-leavened products. The dough
matures or develops through the action of
fermentation on the gluten structure.
Yeasts that are more tolerant and resilient are selected for high-stress processes. The availability of yeasts speciﬁcally
selected for their ability to survive subzero

temperatures has revolutionized the frozen
and parbaked sectors.
As a result of no-time dough processing, volume-processed standard bread has
lost bread's characteristic fermentation
ﬂavor. Consequently, certain yeast suppliers
have turned their attention to yeast strains
that provide excellent and, more interestingly, variable ﬂavor proﬁling in bread.
FLAVOR

Bread's taste and aroma are the result of its
ingredients, the aromas originating from
the yeast's fermentation, and the thermochemical reactions during baking. Yeast
imparts the characteristic ﬂavor of bread
and other yeast-leavened products.
Sugars are metabolized when yeast

produces carbon dioxide. This produces a
spectrum of intermediate metabolites, many
of which are precursors for ﬂavor.
Yeast fermentation products that can
be detected both in dough and in the
ﬁnished bread include ethanol and higher
alcohols, aldehydes, and organic acids,
which are by-products of the yeast's primary metabolic function in dough. Some
of these by-products enhance the rate of
browning reactions and the formation of
melanoids and caramels in the bread crust.
Important substrates for these types of
reactions are sugars and amino acids. By
contributing some of these substrates, the
yeast also inﬂuences the eventual taste and
ﬂavor of the bread.
Continued

THE NUTRITIONAL AND HEALTH BENEFITS OF YEAST
Yeast can naturally contribute signiﬁcant
amounts of numerous nutrients to bread and
baked goods.
VITAMIN D (PHYTOSTEROLS)
Phytosterols are natural plant sterols that have
been shown to effectively lower blood cholesterol, enhance the immune system, and decrease
the risk of certain cancers. The lowering of cholesterol is phytosterol's most documented health
property. When exposed to UV light, ergosterol
is converted to vitamin D. Apart from the prevention of the deﬁciency diseases rickets and osteomalacia, vitamin D is involved in maintaining
calcium balance in the body, normal cell division
and immune system function, a healthy inﬂammatory response, and normal muscle function.
Bakers yeast typically contains 0.5 percent
(w/w) ergosterol, but selected strains can contain up to 1.5 percent ergosterol. The vitamin D
level in yeast can be adjusted to any needs.
B VITAMINS
Soluble in water, the B vitamins found in yeast
are structurally dissimilar yet equally essential
for normal cellular functions, growth, and
development.
Thiamin (B1) acts as a coenzyme in a variety
of critical metabolic reactions related to energy
metabolism. B1 deﬁciency can lead to a variety

of clinical abnormalities, including neurological
and cardiovascular (heart failure) disorders.
Niacin (B3) is involved in glucose and fatty
acid oxidation. It is one of the ﬁve vitamins that
when lacking in human diet is associated with a
pandemic deﬁciency disease called pellagra,
which causes diarrhea, dermatitis, and dementia.
Pantothenic acid (B5) is involved in fatty acid
synthesis and degradation as well as in the synthesis of cholesterol, steroid hormones, heme,
and acetylcholine. B5-deﬁciency symptoms are
similar to those of other vitamin B deﬁciencies.
Impaired energy production, due to low CoA levels, could cause irritability, fatigue, and apathy.
Folate (B9) has a well-established role in the
prevention of neurotubular birth defect (spina
biﬁda). It also has a possible preventative role
against cardiovascular disease, certain cancers,
and neuropsychiatric conditions.
MINERALS
The minerals found in yeast are involved in
growth, development, energy metabolism, and
the reproductive system.
Potassium acts as an osmotic pressure regulator and is involved in the body acid-base balance and muscle contraction. Epidemiological
studies indicate that diets high in potassium can
reduce the risk of hypertension and possibly
stroke.

Zinc is an important constituent of insulin
and the DNA and RNA repair/enzyme function.
It is involved in ﬂavor perception and acts as
vitamin A carrier. Symptoms of zinc deﬁciency
include depressed growth, diarrhea, impotence
and delayed sexual maturation, alopecia, and
eye and skin lesions.
PROTEINS
Proteins are the chief actors within the cell, said
to be carrying out the duties speciﬁed by the
information encoded in genes. The best-known
role of proteins in the cell is as enzymes, which
catalyze chemical reactions. Proteins have
recently been recognized for their role in weight
management and satiety. They represent more
than 50 percent of yeast (w/w).
DIETARY FIBERS
Dietary ﬁbers play a role in maintaining normal
intestinal function and stimulating the immune
system. They are also known to act as prebiotic,
improve insulin resistance, and reduce serum
cholesterol. Yeast typically contains 30 to 40
percent (dry weight) ﬁbers, of which 60% are
beta-glucans.
Beta-glucans, polysaccharides found in
yeast cell walls, have been shown to reduce
blood cholesterol concentrations. Reports have
also been published on the immune beneﬁts of
yeast (Saccharomyces cerevisiae) beta-glucans.

Milling & Baking News - November 26, 2013

Table of Contents for the Digital Edition of Milling & Baking News - November 26, 2013