[For further information on the Electronic Forum on Biotechnology in Food and
Agriculture see Forum website.
Note, participants are assumed to be speaking on their own behalf, unless they state otherwise.]
Sent: 01 July 2004 14:55
Subject: 39: Safety of traditionally fermented foods
I am Obadina Adewale Olusegun, a research assistant and a PhD student at the University of Agriculture, Abeokuta, Nigeria. I am a food microbiologist working on microbiological safety of traditionally fermented African foods.
Much work has been done and documented on food fermentation with regard to developing countries but little or nothing has been done on the safety of these fermented foods consumed in the developing countries. I want to contribute to this conference by writing on the need for work and documentation on safety aspects of African fermented foods.
Fermentation is generally considered as a safe and acceptable preservation technology for improving the hygienic quality and safety of foods (Holzapfel, 2002), but there is need to observe the required basic operating programmes such as Good Agricultural Practices (GAP), Good Manufacturing Practices (GMP) and Good Hygienic Practices (GHP) that should be in place before this can be said of fermentation. Fermentation in developing countries is currently done through the age-old traditional methods with little or no concerns for quality and safety of the products. Food-borne diseases are a major global public health problem, with developing countries bearing the brunt of the problem. Although, statistics on the incidence of food-borne diseases in developing countries are not available. But the high prevalence of diarhoeal diseases particularly in African countries is an indication of underlying safety problems.
The contamination of food prior to consumption is a serious problem in developing countries where the need to eat may outweigh concerns about food safety. So there is need to assess and evaluate the safety of traditionally fermented foods in developing countries.
Obadina Adewale Olusegun,
University of Agriculture,
E-mail: obadinaw (at) yahoo.co.uk
[The paper refered to above, is presumably that of Holzapfel WH (2002). Appropriate starter culture technologies for small-scale fermentation in developing countries. Int J Food Microbiol. 25;75(3):197-212. The abstract of this paper is highly relevant to some of the aspects we wished to see discussed in this conference i.e. "Modern food biotechnology has moved a long way since ancient times of empirical food fermentations. Preservation and safeguarding of food are, however, still major objectives of fermentation. In addition, other aspects, such as wholesomeness, acceptability and overall quality, have become increasingly important and valued features to consumers even in developing countries where old traditions and cultural particularities in food fermentations are generally well maintained. Due to limitations in infrastructure and existing low technologies, rural areas in most developing countries have not been able to keep abreast of global developments toward industrialisation. At the same time, fermented foods play a major role in the diet of numerous regions in Africa and Asia. In many traditional approaches, the advantages of some form of inoculation of a new batch, e.g. by back-slopping or the repeated use of the same container (e.g. a calabash) is appreciated and generally practised. Still, the benefits of small-scale starter culture application as a means of improved hygiene, safety and quality control, in support of HACCP approaches, are not yet realised in small-scale fermentation operations. Approaches and considerations for the selection of pure cultures for small-scale, low-tech applications may differ in some respects from the large-scale industrial approaches practised since 100 years. Selection criteria should take account of the substrate, technical properties of the strain, food safety requirements and quality expectations. Lack of experience in the application of starter cultures in small-scale operations and under rural conditions presents a major obstacle but also an exciting challenge to food microbiologist and technologist. Culture preservation, maintenance and distribution demand special logistic and economic considerations. Quality, safety and acceptability of traditional fermented foods may be significantly improved through the use of starter cultures selected on the basis of multifunctional considerations, also taking into account the probiotic concept and possibilities offered for improved health benefits"...Moderator].
Sent: 01 July 2004 16:43
Subject: 40: Re: Traditional fermentation in developing countries // GE microorganisms
I am Sylvia Uzochukwu from the Department of Food Science and Technology, University of Agriculture, Abeokuta, Nigeria. I am also the Acting Director of our Biotechnology Center in my University. I am in food microbiology and biotechnology.
I congratulate the organizers of the conference, especially the moderator for a job well done.
First, permit me to comment briefly on message 4 (June 17) as it concerns palm wine. Olusola Oyewole's table is very informative and useful. However, I wish to add that palm wine does have a starter - the dregs of palm wine, which is a paste containing mainly lactic acid bacteria and Saccharomyces yeasts. Consequently, a pure mixed culture of Sacharomyces cerevisiae and Leuconostoc dextranicum has also been developed for palm wine and its analogues which works very well. The studies are published, and please contact me for information on these publications.
Also regarding message 4, John Nishio says in message 20 (June 22) that he now knows gari is a fermented food. Gari is not a fermented food. Fermentation in gari is optional. The moderator threw some light on this in some quotations provided after message 3 (June 17). Those who desire a sour taste and a less viscous product, ferment their gari as is done in the Western part of Nigeria. Those who prefer a relatively bland but more starchy or viscous product do not ferment their gari and the production process begins and ends within 24hrs. This is the case in the Mid Western and Eastern parts of Nigeria. It has been shown, as quoted by the moderator in message 3, that the fermentation process is not necessary for the detoxification of cassava, only for flavour for those who want that.
[a) The genus Leuconostoc belongs to the group of lactic acid bacteria. b) Table 2 of Olusola Oyewole's message (nr. 4) indicated that palm wine derived frmo palm in West Africa was at a level of development of 1 (i.e. the microorganisms involved were known), 2 (i.e. the roles of individual microorganisms were known) and 7 (i.e. pilot plant production). Olayinka Edema in Message 30 (25 June) also made an interesting comment about palm wine i.e. "Attempts at improving shelf-lives of African fermented foods end up changing the taste and flavour of the products. For example, bottled and pasteurized palm wine lacks the uniqueness of the fresh, un-bottled palm sap, which is attributed to the fact that the yeasts are alive and well, making the wine bubble and rich"...Moderator]
Dr. Sylvia Uzochukwu
University of Agriculture, Abeokuta
E-mail: suzochi (at) yahoo.com
Sent: 01 July 2004 17:08
Subject: 41: Palm wine - Genetic engineering
This is from Sylvia Uzochukwu, Nigeria, again.
My contribution concerning how biotechnology can be used to improve food quality is this: I work on palm wine and I think that commodity is ready for an input from genetic engineering. Palm wine is the fermented sap of palms. It is a whitish effervescent beverage. Part of the whiteness is soluble, being imparted by microbial gum which have been identified and characterized. The presence of the whiteness limits the uses the sap can be put to. If it can be removed, the sap can be used for non alcoholic juice preparation, table and sparkling wines of international standards, and the products can be exported to fetch hard currency. A yeast can be constructed to decolourise the palm wine as it produces alcohol in it. The enzymes required and the sources of their genes have been identified as well as the detailed protocol for the work. All that is required is the funding for the very expensive reagents and equipment needed for the laboratory work and we shall construct a yeast which can decolourise palm sap/wine for the purposes stated above. I am sure that gradually, as more scientists in the developing countries come to learn about molecular biology techniques, each will begin to see how this exciting new tool can be used to solve his particular research problems just as I have. Massive re-training in DNA manipulating techniques is important for life scientists from developing countries if their countries are not to be left behind in this whirlwind biotechnology revolution which nothing can stop.
Dr. Sylvia Uzochukwu
University of Agriculture, Abeokuta
E-mail: suzochi (at) yahoo.com
[Chapter 4 in "Fermented fruits and vegetables: A global perspective", by
Mike Battcock and Sue Azam-Ali (1998) in FAO's Agricultural Services Bulletin
series (http://www.fao.org/docrep/x0560e/x0560e00.htm), is dedicated to
products of yeast fermentation. Here, they include a section on fermented
plant saps, as many alcoholic drinks are made from the juices of plants,
including coconut palm, oil palm, wild date palm, nipa palm, raphia palm and
kithul palm. For palm wine, they wrote:
"Location of production: Palm 'wine' is an important alcoholic beverage in West Africa where it is consumed by more than 10 million people. Product description: Palm wine can be consumed in a variety of flavours varying from sweet unfermented to sour fermented and vinegary alcoholic drinks. There are many variations and names including emu and ogogoro in Nigeria and nsafufuo in Ghana. It is produced from sugary palm saps. The most frequently tapped palms are raphia palms (Raphia hookeri or R. vinifera) and the oil palm (Elaeis guineense). Palm wine has been found to be nutritious. The fermentation process increases the levels of thiamin, riboflavin, pyridoxin and vitamin B12. Like many African alcoholic beverages, palm wine has a very short shelf-life. The product is not preserved for more than one day. After this time accumulation of an excessive amount of acetic acid makes it unacceptable to consumers. The bark of a tree (Saccoglottis gabonensis) may be added as a preservative. The alkaloid and phenolic compounds which are extracted into the wine have antimicrobial effect (Odunfa, 1985).
Preparation of raw materials: Sap is collected by tapping the palm. Tapping is achieved by making an incision between the kernels and a gourd is tied around to collect the sap which is collected a day or two later. The fresh palm juice is a sweet, clear, colourless juice containing 10-12 percent sugar and is neutral. The quality of the final wines is determined mostly by the conditions used in the collection of the sap. Often the collecting gourd is not washed between collections and residual yeasts in the gourd quickly begin the fermentation.
Processing: The sap is not heated and the wine is an excellent substrate for microbial growth. It is therefore essential that proper hygienic collection procedures are followed to prevent contaminating bacteria from competing with the yeast and producing acid instead of alcohol (Fellows, 1997). Fermentation starts soon after the sap is collected and within an hour or two, the sap becomes reasonably high in alcohol (up to 4%). If allowed to continue to ferment for more than a day, the sap begins turning into vinegar, although the vinegary flavour is preferred by some. Organisms responsible include S. cerevisiae, and Schizosaccharomyces pombe, and the bacteria Lactobacillus plantarum and L. mesenteroides. There are reports that the yeasts and bacteria originate from the gourd, palm tree, and tapping implements. However the high sugar content of the juice would seem to selectively favour the growth of yeasts which might originate from the air. This is supported by the fact that fermentation also takes place in plastic containers. Within 24 hours the initial pH is reduced from 7.4-6.8 to 5.5 and the alcohol content ranges from 1.5 to 2.1 percent. Within 72 hours the alcohol levels increase from 4.5 to 5.2 percent and the pH is 4.0. Organic acids present are lactic acid, acetic acid and tartaric acid (Odunfa, 1985). The main control points are extraction of a high yield of palm sap without excessive contamination by spoilage micro-organisms, and proper storage to allow natural fermentation to take place.
Packaging and storage: Packaging is usually only required to keep the product for its relatively short shelf-life. Clean glass or plastic bottles should be used. The product should be kept in a cool place away from direct sunlight"...Moderator].
Sent: 01 July 2004 17:32
Subject: 42: Impact of biotechnology in food and feed processing in developing countries
I am a Senior Lecturer in Animal Breeding and Genetics in the Department of Animal Science, University of Ibadan, Nigeria, and a promoter of BIOGROW, a biotechnology and biosafety NGO whose objectives include the promotion and dissemination of the understanding and acceptance of the science behind biotechnology among the ordinary people of West and Central Africa region in general and Nigeria in particular.
I have followed this e-conference with keen interest and agree with most of the opinions and ideas of contributors. The most important impact of biotechnology in food (and feed) processing in developing countries especially in Africa will be the removal of toxins and poisons in livestock feed (such as aflatoxin in grains and legumes, cyanide in cassava) and the use of enzymes and additives in high lignin and fibrous grasses and fodder in order to enhance utilisation for livestock. However, one of the major problems in utilising this novel technology in Africa is the low capacity building for an effective utilisation of the benefits of biotechnology.
In answer to one of the questions posed in Message 34 (June 290 by Nand Lal on rumen microorganism-protein supply, I wish to say that the answer may be found in the symposium entitled: International Symposium on "Applications of gene-based technologies for improving animal production and health in developing countries". Vienna, Austria, 6-10 October 2003, jointly organised by FAO and IAEA.Olusanya Olutogun, PhD
[The book of extended synopses, as well as presentations, from the symposium referred to above are available at http://www.iaea.org/programmes/nafa/d3/hlight-d3.html. Proceedings of the symposium should be available soon. For more information on the symposium, contact h.makkar (at) iaea.org...Moderator].
Sent: 01 July 2004 18:50
Subject: 43: Re: Malolactic fermentation // Cheese classes // Vitamins
This is from Obadina Adewale Olusegun, Nigeria, again.
I wish to answer some of the technical questions asked by Nand Lai (Message 1, June 15):1. "Microorganisms that are used in the commercial production of Vitamins":
Among these are Vitamin B12 which is produced commercially by utilizing the synthetic ability of either bacteria or streptomycin. Most commonly, Propionibacterium freudenreichii or a similar organism is grown by the usual fermentation techniques, such as are employed for riboflavin, penicillin, or streptomycin. The organism is grown in 10,000 to 50,000-gal (40 to 2000 metre cube) tanks in a medium of yeast extract, minerals, and sucrose or other carbohydrate for a period of 72-120 hr after inoculation. Optimum vitamin titers of 2-6 mg/liter are obtained under conditions of mild aeration, though the organism can grow anaerobically. Since the vitamin is almost entirely contained in the cells, it can be recovered by centrifugation of the final broth. The cells can be dried, and used directly as a food or animal-feed supplement. The product can further be purified for drug uses. Vitamin B12 can also been produced as a by-product during the production of streptomycin and certain other antibiotics.
More so, irradiated yeast is a source of vitamin D2 and is used in supplementing rations of livestock. Provitamin ergosterol can be extracted from yeast and, and when irradiated and purified, will yields crystalline vitamin D2.2. "Classification of cheese":
Two major classes of cheese exist, fresh and ripened. Fresh cheeses are simpler to make than ripened, are more perishable, and do not develop as intense flavors, but give a mild acid, slightly aromatic favor and soft, smooth texture.
Fresh Cheeses: Three basic groups characterize fresh cheese types: group 1- ricotta and Broccio; group 2 - cottage, Neufchatels, and cream; and group 3 - mozzarella. Curd formation for these fresh cheese groups results from a combination of acid (pH 6.0) and heat (80 degrees), as in group 1; from acid alone to give a pH 4.6, as in group 2; or from rennet (an enzyme preparation) at pH 6.3, as in group 3; Especially a dehydration of protein occurs, along with a partial or complete reduction of the negative electrical charges which surround the surfaces of the milk proteins. At a critical point, precipitation occurs, leading to a smooth gelatinous curd of varying strength. The curd may be scooped directly into cloth bags or perforated containers for immediate draining and eventually packaging or it is cut and cooked, followed by drainage of whey, salting and creaming.
Ripened Cheese: Ripened Cheese is exposed to an optimum environment of temperature and moisture for a period of time to attain characteristic flavor, texture, and appearance. It may be made from raw heat-treated or pasteurized milk that is coagulated with a rennet preparation to form a smooth curd. After cutting and cooking to 35-55 degree Celsius, the curds are salted, before or after pressing, and shaped. The pressed curds, usually salted, may be given a special microbial application, and then are usually held at 5-15 degree Celsius in rooms under controlled humidity (85-95 degree Celsius) to develop the desired traits. All standard ripened cheeses are salted, and the milks from which they are made are always coagulated with rennet in the presence usually of small amount of lactic acid and sometimes added calcium chloride.
"Can one class of cheese be converted into other class?": Processed cheese is made from natural types. Nearly any natural cheese can be processed, except that for blue cheese technical difficulties cause blackening of the blue mold due to the high heat.
Obadina Adewale Olusegun,
University of Agriculture,
E-mail: obadinaw (at) yahoo.co.uk
[Vitamin B12 (cobalamin) is produced by microorganisms which are either free living or symbiotic in the rumen or the intestines of vertebrates. Large scale production of this important biotechnology product is carried out using a number of bacterial species, including Pseudomonas denitrificans and Propionibacterium freudenreichii...Moderator].