Improved nutrient bioavailability

Tempeh fermentation may increase the bioavailability of proteins, lipids, carbohydrates and minerals such as iron and zinc (Steinkraus et al., 1983 Nout & Rombouts, 1990 Hachmeister & Fung, 1993 Rodriguez-Burger et al., 1998 Astuti et al., 2000). The growth of the fungus reduced the concentration of low molecular carbohydrates and increased the dietary fibre content (Nout & Rombouts, 1990). Broiler chickens fed with barley tempeh gained more body weight than those fed with unfermented...

Removal of antinutritional compounds

Legume seeds contain a variety of anti-nutritional factors 1) flatulence-producing factors, such as tri- and tetrasaccharides, raffinose and stachyose, verbascose 2) protease inhibitors, such as trypsin and chymotrypsin inhibitors 3) tannins 4) phytic acid 5) haemagglutinins or lectins 6) favism-inducing factors (Nout & Rombouts, 1990). Cereal grains contain several anti-nutritional factors such as 1) phytic acid, 2) tannins, and 3) polyphenols (Sandberg & Svanberg, 1991 Svanberg et al.,...

Production of volatile compounds

Flavour changes during tempeh fermentation could be due to the formation of volatile compounds. A headspace diffusion method was used to collect volatile compounds from several strains of R. oligosporus grown on malt extract agar (MEA) plates, soybean tempeh, and barley tempeh (II). The ten R. oligosporus strains tested on MEA had very different colony morphologies, but still produced similar volatile profiles, except for slight variations among the minor volatile compounds (e.g....

Mathematical modeling of fungal growth

Many mathematic modeling methods have been developed for predicting fungal growth in solid-state substrate fermentation. Mitchell et al (1991a) developed a method for describing the growth of R. oligosporus in a model solid-state fermentation system. Equations were presented for the release of glucoamylase, the diffusion of glucoamylase, the hydrolysis of starch, the generation and diffusion of glucose, and the uptake of glucose and conversion into new biomass. A cellular automata method was...

Indirect methods for fungal quantificationhyphal length and ergosterol content

Quantification of mould biomass in SSF remains difficult. A direct gravimetric biomass determination would provide the most accurate estimate, but this is almost impossible due to the difficulty in separating fungal biomass from the substrate (Harris & Kell, 1985). Therefore, many indirect methods have been used to determine fungal biomass in SSF, such as CO2 evolution (Steinkraus et al., 1983), determination of hyphal lengths (I Olson, 1950 Schn rer, 1993), ergosterol (I Seitz et al., 1979...

Abstract

Microbial dynamics during barley tempeh fermentation. Doctoral dissertation. Tempeh is a traditional staple food in Indonesia mainly made from soybeans. Barley tempeh has been developed by adapting the soybean tempeh process. During soybean tempeh fermentation, the filamentous fungus Rhizopus oligosporus is dominant. However, other fungi and bacteria also occur, which may influence tempeh quality or even constitute a health risk. Introduction of food-grade lactic acid bacteria...

What is tempeh

Tempeh production (especially soybean tempeh) has been extensively reviewed (Ko Swan & Hesseltine, 1979 Steinkraus et al., 1983 Nout & Rombouts, 1990 Hachmeister & Fung, 1993 Astuti et al., 2000 Nout & Kiers, 2005). In general, fresh tempeh of good quality is defined as a compact and sliceable mass of cooked particles of raw materials covered, penetrated and held together by dense non-sporulated mycelium of Rhizopus spp. (Nout & Rombouts, 1990). Tempeh is considered as the...

Microbial diversity in tempeh fermentation

Traditional tempeh is the result of a mixed culture fermentation by a diverse group of microorganisms including moulds, yeasts, lactic acid bacteria and different gram-negative bacteria (Steinkraus et al., 1983 Nout, 1995). Rhizopus oligosporus is the dominant tempeh fungus (Sharma & Sarbhoy, 1984), although some other moulds, such as R. oryzae and Mucor spp, may also contribute to the flavour, texture or nutritive value (Wiesel et al., 1997). Lactic acid bacteria may contribute to the...

Antimicrobial effects of R oligosporus

R. oligosporus can inhibit the growth and aflatoxin B1 accumulation of Aspergillus flavus and A. parasiticus (Nout, 1989). R. oligosporus has been reported to produce 4 to 5 anti-bacterial compounds during soybean tempeh fermentation (Anon, 1969 Wang et al., 1969 Nowak & Steinkraus, 1988). The fungus also produces phenolic compounds that inhibit the growth of pathogenic bacteria such as Helicobacter pylori (Berghofer et al., 1998 McCue et al., 2003 Correia et al., 2004a Correia et al, 2004b...

Characteristics of barley

The gross composition of barley varies notably between varieties, consisting of 49-66 starch, 14-28 dietary fibre and 9-22 crude protein (Oscarsson et al., 1996). Consumption of barley products may elicit lower metabolic responses (i.e. lower blood glucose and insulin responses) and induce a greater feeling of satiety compared with white wheat bread (Granfeldt et al., 1994) and could therefore decrease the risk for type 2 diabetes (McKeown, 2004). Consumption of barley products may also reduce...

Enzymes produced by R oligosporus

During tempeh fermentation, the substrate is degraded by R. oligosporus enzymes, such as carbohydratases (e.g. polygalacturonase, endocellulase, xylanase, arabinanase and small quantities of a-D-galactosidase, -B-galactosidase, -D-xylosidase, a-L-arabinofuranosidase and a-D-glucosidase), lipases, proteases and phytases (Nout & Rombouts, 1990). In contrast, Rehms and Barz (1995) found that R. oligosporus did not produce a-galactosidase and consequently can not degrade flatulence-causing...

Potential online fungal biomass measurement capacitance and image analysis

The above-mentioned methods for determination of fungal growth during tempeh fermentation are not rapid enough to follow tempeh production on an industrial scale. Instead, online measurement is needed. A technique for measuring fungal growth based on the biomass-dependent changes in electrical capacitance at 0.30 MHz has been developed (Davey et al., 1991 Penaloza et al., 1992). However, with this technique, an electrode is inserted into the substrate, which increases the risk of contamination....

Methods for quantitative determination of microorganisms during tempeh fermentation

From microbiological investigations of tempeh, we know that traditional tempeh fermentation is a mixed-culture fermentation with R. oligosporus as the dominant species. LAB and yeasts might improve the safety and nutritional value. Specific quantification methods are required to investigate the interrelationships and effects of different microorganisms during barley tempeh fermentation. Tempeh fermentation is a solid-substrate fermentation process (SSF) (Fig. 11), which makes quantification...

Papers IIV

This thesis is based on the following papers, which will be referred to by their I. Feng, X. M., Eriksson, A.R.B., Schn rer, J., 2005. Growth of lactic acid bacteria and Rhizopus oligosporus during barley tempeh fermentation. International Journal of Food Microbiology 104 (3), 249-256. II. Feng, X. M., Larsen, T. O., and Schn rer, J., 2006. Production of volatile compounds by Rhizopus oligosporus during soybean and barley tempeh fermentation. International Journal of Food Microbiology, III....

Contents

Microbial fermentation and world food supply 7 The basic process of tempeh production 9 Substrates used for tempeh production 9 Barley for tempeh production 13 Comparison of barley tempeh with soybean tempeh 14 Microbial diversity in tempeh fermentation 18 The tempeh fungus Rhizopus oligosporus 19 Enzymes produced by R. oligosporus 20 Anti-microbial effects of R. oligosporus 20 Application of R. oligosporus in other fields 21 Effects of inoculum concentration of R. oligosporus on tempeh Effects...

Vitamin production by bacteria during tempeh fermentation

Vitamin Bi2 is one of the most frequently studied vitamins produced by bacteria. It is normally present in insufficient amounts in vegetarian foods, while it is found in high amounts in animal food sources (Murphy & Allen, 2003). Bacteria such as Klebsiella pneumoniae, Kl. pneumiae spp. ozenae, Kl. terrigena, Kl. planticola and Enterobacter cloacae can produce vitamin B12 during tempeh fermentation (Okada et al., 1985b). Especially Kl. pneumoniae (formerly Aerobacter aerogenes), is...

Main findings of the thesis

Several lactic acid bacteria, including Lactobacillus plantarum, Lactobacillus fermentum, and yeasts, including Saccharomyces cerevisiae, S. boulardii, Pichia anomala and Kluyveromyces lactis, could grow together with R. oligosporus without influencing the growth of R. oligosporus when inoculated at 4 log cfu g moist barley (I and III) 2. Yeast co-inoculation enhanced the ergosterol contents of barley tempeh by 7.1-17.5 g g dry tempeh (III) 3. R. oligosporus produced different volatile profiles...

Comparison of barley tempeh with soybean tempeh

Although the basic fermentation process is similar, there are still several differences between the barley and soybean tempeh processes (Fig. 3). R. oligosporus strains, which can produce soybean tempeh of good quality, do not always produce barley tempeh of good quality (Berg et al., 2001). Barley is pearled before soaking, while soybean is dehulled before or after soaking. For barley tempeh production, the times for soaking, boiling or incubating are shorter than for soybean tempeh (II)....

Application of R oligosporus in other fields

Due to the wide range of enzymes produced, the ability to grow rapidly at high temperature and the production of anti-microbial compounds as above-mentioned, R. oligosporus has recently received attention in other fields of applied microbiology, such as sufu production (Han et al., 2003), agro-industrial solid waste treatment (Christen et al., 2000), the production of phenolic compounds from agricultural wastes (McCue et al., 2003 Correia et al., 2004b Vattem et al., 2004) and bioremediation of...

Vitamin production by fungi during tempeh fermentation

Many vitamins, such as niacin (B3), riboflavin (B2), pyridoxine (B6), pantothenic acid and thiamine, can be produced by the tempeh fungus R. oligosporus (Nout & Rombouts, 1990 Mugula, 1992 Shurtleff & Aoyagi, 2001 Nout & Kiers, 2005). Rhizopus oryzae, another important fungus frequently found in tempeh products (Samson et al., 1987), has also been reported to produce niacin, vitamin K, ergosterol, and tocopherol, pyridoxine, riboflavin and biotin (Mugula, 1992 Wiesel et al., 1997). The...

Effects of yeasts on tempeh fermentation

Yeasts are considered to be the oldest domesticated microorganisms, and have been used to produce alcoholic beverages and leaven bread dough for millennia (Walker, 1999). Certain yeasts have probiotic potential (van der Aa Kuhle et al., 2005), prevent the growth of moulds in storage (Druvefors, 2004), inhibit the production of mycotoxins (Petersson et al., 1998), or bind mycotoxins to the cell wall and consequently reduce the risk of occurrence of mycotoxins in foods (Yiannikouris et al., 2003...

Realtime PCR quantification

Value Amplification Efficiency Graph

In real-time PCR, PCR amplification is linked to a detection process of the PCR products. Thus, amplification and product detection are performed at the same time, which makes it possible to follow the reaction kinetics. Several PCR products detection methods have been developed, including labelled oligonucleotide probes oligoprobes and fluorescent dyes that bind to dsDNA and enhance their fluorescence while binding Mackay, 2004 . Real-time PCR quantification has been used to detect and...

Origin of tempeh

Tempeh, also called 'tempe kedele' in Indonesia, is traditionally made from soybeans Steinkraus et al., 1983 . Tempeh originated in central and east Java Indonesia at the beginning of the 18th century, and is now Indonesia's most popular soy-protein food Astuti et al., 2000 . Tempeh-like products have also been produced in China, such as soybean koji Shurtleff amp Aoyagi, 2001 or Douchi Li-Te et al., 2003 Li-Te et al., 2004 . Douchi Fig.1 is made from black or yellow beans fermented by Mucor...

Potential human health risks of tempeh

No cases of food poisoning have ever been reported after consuming tempeh Ko Swan amp Hesseltine, 1979 . However, there is still a risk due to the potential growth of moulds and pathogenic bacteria Table 2 , and the production of mycotoxins and bacterial toxins. Pathogenic bacteria do not grow well in acidified substrates and even if they can grow, they are normally controlled by LAB Table 2 . The only bacterial toxin reported in tempeh hitherto is produced by Pseudomonas cocovenenans in tempeh...

Aims of this thesis

Soybean tempeh fermentation has been extensively documented Steinkraus et al., 1983 Nout amp Rombouts, 1990 Nout amp Kiers, 2005 , but considerably less is known about barley tempeh. For instance, in soybean tempeh it was found that the presence of other microorganisms such as yeasts and lactic acid bacteria LAB could enhance the nutritional value and hygienic safety of soybean tempeh fermented by R. oligosporus Suparmo, 1989 Ashenafi amp Busse, 1991b Nout, 1995 Wiesel et al., 1997 . In this...

Microbial food fermentation and world food supply

According to the USA Census Bureau's world population clock, the world population is 6.5 billion in 2006, and will reach 9 billion people in the year 2050. An increased food supply is needed to feed this growing population. To meet the demand, legumes, cereal grains and even some agricultural residues that are presently fed to animals and recovered in the form of milk, eggs, broilers, pork and beef, must be converted to human food. In terms of protein generation, meat production on average...

Effects of inoculum concentration of R oligosporus on tempeh fermentation

The inoculation levels of R. oligosporus strongly influenced tempeh fermentation. When R. oligosporus was inoculated at approximately 104 spores g moist substrate, a barley tempeh cake with dense mycelial growth was obtained after 20 h IV . With inoculation at approximately 102 spores g moist barley, the fungus grew more slowly and a barley tempeh cake with dense mycelial growth was not obtained until after 28 to 32 h IV . This slow growth may increase the risk of contamination with pathogens....

Effects of lactic acid bacteria on tempeh fermentation

Fermentation Tempeh Process

There are no reports of food poisoning caused by consuming traditional soybean tempeh Ko Swan amp Hesseltine, 1979 . Nout amp Rombouts 1990 suggested that this safety is due to 1 inherent properties of Rhizopus spp., 2 presence of lactic acid bacteria LAB , 3 incubation under micro-aerobic conditions, and 4 the customary heating prior to consumption. Table 2. Growth of potential pathogenic bacteria and their inhibition by lactic acid bacteria LAB during tempeh fermentation Growth of pathogenic...

Foods made from tempeh

Meat Fermentation Process

Soybean tempeh can be sold fresh, refrigerated Fig. 5 , frozen or even distributed in cans. This fermented product is remarkably versatile and can be served in hundreds of different Western or Asian-style recipes, such as tempeh burgers and sushi Fig. 6 tempeh, lettuce and tomato sandwiches tempeh chops topped with apple sauce crisp slices or cubes added to salads, soups, pizza toppings, stir-fried rice, casseroles, sauces or tacos. The most popular and simplest way of serving is shallow-fried...

The tempeh fungus Rhizopus oligosporus

Rhizopus Oligosporus

Tempeh has been produced in Indonesia for many centuries. However, it was the Dutch scientist Prinsen Geerligs, who in 1895 identified the tempeh mould for the first time Shurtleff amp Aoyagi, 2001 . Many different moulds are found in tempeh, but species within the zygomycete genus Rhizopus dominate Steinkraus et al., 1983 . Rhizopus Mucorales, Mucoraceae, Zygomycota includes three species groups R. oryzae group, R. stolonifer group, and R. microsporus group Schipper amp Stalpers, 1984 , with...

Barley for tempeh production

Barley is the second most abundant cereal grain after wheat grown in Northern Europe. In Sweden, the average yearly production was about 1.7 million tons during the period 1993 to 2005. This was used in the following way 62.3 for animal feeds, 9.9 for beer production and 0.5 for direct human consumption, with the remainder being exported Euro Stat data, supplied by Christina Wikberger, Swedish Board of Agriculture, Statistics Division . Thus, only 10.4 of barley is used for human consumption in...

Barley tempeh production

Barley tempeh has been fermented through a process similar to soybean tempeh Hesseltine et al., 1963 Hesseltine et al., 1967 . It was found that Rhizopus spp. with highly active proteolytic and lipolytic enzymes, but little or no amylase activity, were suitable for producing tempeh from cereal grains wheat, barley, oat, rye and rice . This early attempt to produce barley tempeh used dehulled and cracked barley Hesseltine et al., 1967 . However, commercial barley tempeh has not yet been...

The basic process of tempeh production

Although different substrates can be used to produce tempeh, the basic fermentation process is similar for all substrates. It includes soaking, dehulling if necessary , boiling and fermenting. The main differences between different substrates used in tempeh fermentation are the selection of optimal pre-treatments e.g. when cereals are used it is sometimes necessary to modify the surface of the grain by cutting, cracking or pearling to obtain good growth of the mold , optimal soaking, boiling...