Bread is a fermented food and it may boost your colon

Bread is a staple food in most developing countries and the consumption in Morocco is estimated to 210.44 Kg/per/year as equivalent grain. The use of baker's yeast is being now used more than the traditional ferment and some nutritional properties of bread are being lost because of the substitution of the traditional ferments with the baker's yeast. Sour-dough bread is the most popular food in many african and Arab countries and the traditional method of bread making is still adopted. Rural populations have long prepared their own leavens or traditional ferments. After each kneading operation, a portion of dough is retained for starting the next batch the following day. This ferment may vary widely in its microflora because of the non controlled traditional kneading procedures adopted. No commercial cultures or leavening material is used in the preparation of bread, so every family may have its own ferment or traditional starter.

Moroccan bread is usually round shaped and can vary widely in volume. Home baked bread tends to be very flat when prepared from barley or corn flour. This type of bread and many related products are widely consumed in North Africa and in the Middle Eastern countries. Several species of lactobacilli interact with Candida krusei in fermentation of sour-dough rye bread. The contribution of yeast-lactic acid bacteria interaction to some fermented foods was also reported.

The origin of bread as one of the first technologies known to man is not precisely known. The texture and flavour resulting from fermentation would have been most attractive in comparison with unleavened breads and thus the use of fermentation for bread making had persisted.

The earliest method of obtaining reliable leavens or fermenting materials was to keep back a loaf of fermenting dough to be used in the new dough the following day. The loaf of dough kept for the next day is called the sour ferment and bread obtained after a long fermentation (one night) is characterized by a distinguishable acidic taste and agreeable flavour due to the close conjunction of yeasts with lactic acid bacteria (LAB)

In our research we demonstrated that the micro-organisms associated with the traditional Moroccan sourdough bread were represented by Candida milleri and Saccharomyces  cerevisiae for the yeasts and by Lactobacillus plantarum and L. brevis for the LAB. 

It is assumed that most of the minerals are binded by phytates in cereals due to the high chelating reaction of the molecule of myo-inositol hexakis-dihydrogeno phosphate (IP6). The bioavailability of some important minerals is lowered by the phytates as well as the reduction of the digestibility of proteins, starch and lipids, and since we showed that the traditional sourdough ferments in Morocco may contain two kinds of microorganisms lactic acid bacteria and yeasts, these microorgansims were isolated and studied for their phytase activity. We could obtain the same characteristics as the traditional sourdough ferment, with the  selected strains of lactic acid bacteria and yeast strains isolated from the traditional sourdough ferment.

Nutritional properties related to the traditional sourdough ferments and concerning the destruction of phytates and to increase the bioavailability of minerals were studied for elucidating the role of a mixed fermentation in bread making by yeasts and lactic acid bacteria.

 Phytate biodegradation activity in traditional bread starters.

Nutritional properties related to the natural sourdough starters and concerning the destruction of phytates to increase the bioavailability of minerals need be studied deeply for elucidating the role of a mixed fermentation in bread making by yeasts and lactic acid bacteria.

Phytase activity in sourdough bread started with traditional starters and some selected isolates of lactic acid bacteria and yeasts were studied. Phytase activity was studied in natural sour-dough bread starters. Physico-chemical characteristics including phytic acid hydrolysis, dough rising capacity and pH were determined in the flour and during the sourdough fermentation. In parallel, microorganisms involved in the fermentation (yeasts and lactic acid bacteria) were also determined and characterized. Results showed a net decrease of the phytic acid contents in sour-doughs started with traditional starters. A wide variation in the phytase activity was observed (23.4 to 84.7 %) among the samples. The pH was decreased to low levels and values ranged from 3.49 to 3.80. The dough rising capacities could reach high levels in some samples due to the yeast strains activities, and values varied also widely from 20 mL to 115 mL. The microorganisms counts showed high levels at the end of the fermentation indicating a higher fermenting activity of the starters. Yeasts populations showed a wide variation between 3.4x10⁶ and 2.6x10⁸ cfu/g. Lactic acid bacteria had also high counts in the sourdough fermentation with a maximum of 7.7x10⁸ for cocci and 5.8x10⁸ cfu/g for rods. The phytase activity was also demonstrated in starter cultures made of lactic acid bacteria and yeast isolates. The most interesting activity was found in the starter made of Saccharomyces cerevisiae combined with Lactobacillus plantarum and Leuconostoc mesenteroides.

The traditional sourdough ferments are still used in rural area in Morocco. This fermentation may have some beneficial nutritional properties of bread which is a staple food in Morocco. Wheat bread is not the only bread consummed in this country but also barley and corn. Barley bread is very popular and very frequently recommended for people having digestive troubles. It is also assumed that most of the minerals in cereals are binded by phytates due to the high chelating reaction of the molecule of myo-inositol hexakis­dihydrogeno phosphate (IP6). The bioavailability of some important minerals is lowered by the phytates as well as the reduction of the digestibility of proteins, starch and lipids. In fact, any process that can release iron from the chelating agents mainly phytates would be a very promoting way to increase the iron uptake by people suffering from iron deficiencies.

Nutritional properties related to the natural sourdough starters and concerning the destruction of phytates to increase the bioavailability of minerals need to be studied deeply for elucidating the role of a mixed fermentation in bread making by yeasts and lactic acid bacteria.

In the present work physico-chemical properties as well as phytase activity in sourdough bread started with traditional starters and some selected isolates of lactic acid bacteria and yeasts were studied.

Sourdough ferments were collected from different regions in Morocco and studied for their physico-chemical and microbiological properties in barley dough fermentation. The chemical characteristics included pH, dough rising activity, dough spread test, (farinograph and alveograph). In parallel, the microbial counts of the involving microorganisms (yeasts and lactic acid bacteria) were determined. Results showed that the pH was decreased to low levels and values ranged from 3.49 to 3.80. A wide variation in the phystase activity was observed (23.4 to 84.7 %) among the samples The dough rising capacities could reach high levels in some samples due to the yeast strains activities, and values varied also widely from 20 mL to 115 mL. The microorganisms counts showed high levels at the end of the fermentation indicating a higher fermenting activity of the starters. Yeasts populations showed a wide variation between 3.4x10⁶ and 2.6x10⁸ cfu/g. Lactic acid bacteria had also high counts in the sourdough fermentation with a maximum of 7.7x10⁸ for cocci and 5.8x10⁸ cfu/g for rods. The phytase activity was also demonstrated in starter cultures made of lactic acid bacteria and yeast isolates. The most interesting activity was found in the starter made of Saccharomyces cerevisiae combined with Lactobacillus plantarum and Leuconostoc mesenteroides.

Mycotoxins degradation in sourdough bread fermentation

Mycotoxins are natural food and feed contaminants. These compounds are produced by moulds species such as Aspergillus flavus, Aspergillus flavus subsp parasiticus and Aspergillus nomius. The most studied mycotoxins are

aflatoxins (AFB1, AFB2, AFG1, AFG2, AFM1 and AFM2). Aflatoxins are of great concern because of their detrimental effects on the health of humans and animals, including carcinogenic, mutagenic, teratogenic, and immunosuppressive effects.

In 1997, the joint FAO/WHO Expert Committee on Food additives provided qualitative and quantitative information on aflatoxins and concluded that aflatoxins should be considered as carcinogenic food contaminants. Some studies showed a correlation between dietary exposure to aflatoxins and the incidence of Human liver cancer in some areas, especially in Africa and Asia.

Several works were carried out on the removal and/or the detoxication of aflatoxin and some microorganisms were reported to be capable of degrading aflatoxins such as Flavobacterium aurantiacum, the degradation of AFB1 by this strain would be enzymatic.

Some strains of lactic acid bacteria were found to be active in removing AFB1 from contaminated media by the contact method without further incubation.

Lactic acid bacteria (Lactobacillus, Lactococcus and Pediococcus species) are used extensively for the manufacture of many fermented products. In Morocco, Sourdough bread fermentation is still used especially in the rural area where the baker’s yeast is not found because of the lack of refrigeration. This fermentation is due to lactic acid bacteria and yeasts. Theses microorganisms are not only involved in the flavour characteristics through the acid and aroma production but they have also some nutritional and detoxicant properties.

In the present work the activity of four sourdough ferments (L1, L2, L3 and L4) on AFB1 and AFG1 was studied as well as the microbiological and physico-chemical characteristics of the dough.

Wheat flour was contaminated with aflatoxins B1 and G1 in the concentration of 240µg/kg. 4 trials (and a control) were carried out which were inoculated with traditional sourdough ferments in the proportion of 10%. The control was inoculated with the baker’s yeast. All the assays were kneaded and introduced in plastic boxes and incubated for 6 hours at 30°C. Aflatoxins B1 and G1 were determined before incubation just after kneading and after 6 hours incubation. Results showed a drastic removal or degradation of the two mycotoxins with a reduction of 92 % for AFG1 and 79.16 % for AFB1 by the ferment L1. All the ferments used in this study were characterized for the microorganisms involved in the fermentation and also the physico-chemical properties. The former concerned the yeasts and lactic acid bacteria while the later included pH, Dough rising capacity. Results showed high counts of lactic acid bacteria, which correlate with the pH decrease. Yeasts reached also high numbers in all the trials, which lead to a high dough risintivity.