Rhizopus oligosporus and yeast co-cultivation during barley tempeh fermentation-Nutritional impact and real-time PCR quantification of fungal growth dynamics

• Barley tempeh was produced by fermenting barley kernels with Rhizopus oligosporus. The potential of the yeasts Saccharomyces cerevisiae (three strains), S. boulardii (one strain), Pichia anomala (one strain) and Kluyveromyces lactis (one strain) to grow together with R. oligosporus during barley tempeh fermentation was evaluated. All yeast strains grew during the fermentation and even during cold storage of tempeh (P < 0.01). The growth of yeasts slightly increased the ergosterol contents, but did not influence amino acid contents and compositions, and did not reduce phytate contents. Slight increases of vitamins B6 and niacinamide, and slight decreases of B1 and biotin were observed. Quantification of fungal growth is difficult during mixed species fermentations because ergosterol is found in all fungal species, and colony-forming-unit (cfu) estimations are not reliable for R. oligosporus and other sporulating fungi. Therefore, we developed a quantitative real-time PCR method for individually quantifying S. cerevisiae and R. oligosporus growth in barley tempeh. The PCR results were highly correlated with the ergosterol content of R. oligosporus and with the number of cfu of S. cerevisiae. Thus, real-time PCR is a rapid and selective method to quantify yeasts and R. oligosporus during mixed species fermentation of inhomogenous substrate such as barley tempeh. © 2006 Elsevier Ltd. All rights reserved.

Ämnesord

NATURVETENSKAP  -- Biologi -- Mikrobiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Microbiology (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Industriell bioteknik -- Annan industriell bioteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Industrial Biotechnology -- Other Industrial Biotechnology (hsv//eng)

Nyckelord

Barley tempeh

Nutrition

Real-time PCR

Rhizopus oligosporus

Yeast

article

barley

coculture

fermentation

food control

food handling

fungus spore

growth

development and aging

microbiology

polymerase chain reaction

Rhizopus

species difference

Coculture Techniques

Food Microbiology

Food Technology

Hordeum

Species Specificity

Spores

Fungal

Yeasts

Fungi

Hordeum vulgare subsp. vulgare

Kluyveromyces

Kluyveromyces lactis

Oligosporus

Pichia

Pichia anomala

Rhizopus microsporus var. oligosporus

Saccharomyces cerevisiae

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)