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Fermentation in Food Processing

Gopalarao vuppala*, Rama Krishna, Krishna Murthy

Montissory Siva sivani institute of science and technology, Gurraju palem, Mylavaram, Vijayawada, Andhra Pradesh, India.

*Corresponding Author:
Gopalarao vuppala
Montissory Siva sivani institute of science and technology, Gurraju palem, Mylavaram, Vijayawada, Andhra Pradesh, India.

Received date: 13 April 2015 Accepted date: 25 May 2015

Visit for more related articles at Research & Reviews: Journal of Microbiology and Biotechnology


Food Processing 1, microorganism2, fermentation3, contaminated4


The WHO food safety unit has given high priority to the analysis space of fermentation as a method for preparation/storage of food. One main reason for this is often that in developing countries, one tenth of the kids beneath 5 years old-time dies because of dehydration. The dehydration is especially caused by incidences of diarrhea. The most cause for obtaining diarrhea is that the intake of food not having the acceptable customary concerning the sanitary condition [1]. The sanitary customary of a food relies on the process and handling of the food, yet as on the conditions of the raw materials. A food item ready from water contaminated with infective microorganisms can in turn be contaminated, and a health risk. Carboxylic acid fermentation of food has been found to cut back the chance of getting infective microorganisms grow within the food [2].

Definition of fermented food

Campbell-Platt (1987) has outlined soured foods as those foods that are subjected to the action of micro-organisms or enzymes in order that fascinating organic chemistry changes cause important modification to the food. However, to the biologist, the term ”fermentation” describes a sort of energy-yielding microbe metabolism during which AN organic substrate, sometimes a supermolecule, is incompletely change, and an organic supermolecule acts because the lepton acceptor (Adams, 1990). This definition means processes involving alcohol production by yeasts or organic acids by carboxylic acid microorganism area unit thought of as fermentations [3], however not the assembly of fish sauces in Southeast Asia, that also has not been shown to possess a big role for microorganisms, and not the tempe production since the metabolism of the fungi isn't fermentative in step with Adams definition. Whichever definition used, foods submitted to the influence of carboxylic acid manufacturing microorganisms is taken into account a soured food [4].

Classification of fermented foods

Fermented foods are often classified in many alternative ways that, Dirar ( 1993) says that in Southeast Asia the classification usually is in step with the type of ten organism concerned (Yokotsuka, 1982) [5]. Alternative classifications area unit supported goods (Campbell-Platt, 1987) (Odunfa, 1988) (Kuboye, 1985). Dirar presents the normal Sudanese classification that's supported the operate of the food. The various classifications show the various viewpoints of the authors, and infrequently a classification that works o.k. in one a part of the globe isn't appropriate in alternative elements [6].

Benefits of fermenting food

Many hard milk merchandise, that square measure eaten as they're, contain living microorganisms. Acidofilus milk, filmjölk, yoghurt [7], junket and kefir square measure hard milks containing either carboxylic acid microorganism (LAB) alone or each workplace and yeast or mixed cultures manufacturing in the main carboxylic acid or a mixture of carboxylic acid and tiny amounts of alcohol. Kumiss is hard milk manufactured from mare’s milk employing a mixed culture [8]. Lassi in Bharat, a hard milk consumed as a drink when dilution with water, and Yakult in Japan and China square measure typical hard milk merchandise manufactured from mixed culture by spontaneous fermentation [9]. Different milk primarily based merchandise that square measure hard with some cereals square measure flummery that could be a hard yogurt like product containing cooked whole grains and prokllada that is principally hard whey with addition of style enhancing substances [10]. Lao-chao, a hard, glutinous, slightly alcoholic, steam burned rice, maheu a non-alcoholic drink from maize, sorghum or millet, pozol that is either a thick dish like food or a skinny drink manufactured from maize flour, a thick inebriant the same as brew manufactured from sorghum, and tapé a thick pasty hard food containing alcohol made of millet or maize however additionally some times from cassava square measure typical samples of hard foods manufactured from cereals [10]. Foods like injera from tef, and kisra from sorghum square measure normally created when chemical change dough for 2 or 3 days with or while not starter. The common hard legume merchandise embrace hama-natto that could be a soybean paste, used for twelve ingredient, oncom manufactured from groundnut presscake, or soybean presscake used as a relish, hard soy milk and sufu manufactured from soybean curd, mould, salt and alcohol. Kimchi could be a well-liked hard food created in the main of vegetables in Korean Peninsula. Preserved fruits and vegetable square measure common in several countries and dish could be a standard product created by chemical change cabbage. German sausage (smoked) [11], Italian sausage, Lebanese Republic bologna (sausage), Longaniza (sausage), and Teewurst square measure typical hard meat merchandise of Europe. Whereas paak manufactured from fish and cereal by carboxylic acid fermentation and pin dang and tarama manufactured from hard roe square measure typical hard fish merchandise of the way jap countries [12].

Microflora in fermented foods

By tradition, carboxylic acid bacterium (LAB) square measure the foremost normally used microorganisms for preservation of foods. Their importance is associated in the main with their safe metabolic activity whereas growing in foods utilizing accessible sugar for the assembly of organic acids and alternative metabolites. Their common prevalence in foods and feeds plus their lasting use contributes to their natural acceptance as GRAS (Generally Recognized as Safe) for human consumption (Aguirre & Collins, 1993) [13]. However, there square measure several varieties of hard foods during which the dominating processes and finish product square measure contributed by a combination of endogenous enzymes and alternative microorganisms like yeast and mildew. Very often, a mixed culture originating from the native microflora of the raw materials is in action in most of the food fermentation processes. However, in associate industrial scale a selected outlined starter culture that has been developed beneath controlled conditions [14] is of 1st preference so the qualities of the finished product might be systematically maintained day once day. Moreover, a contemporary methodology of gene-technology makes it doable for the microbiologists to style and develop starter cultures with specific qualities. several microbiological studies handle identification of organisms isolated from varied hard foods. Carboxylic acid bacterium isolated from tomatoes that were naturally hard beneath partial anaerobic conditions were found to be Leuconostoc mesenteroides [15], eubacterium brevis and streptococci sp. (Beltrán-Edeza & HernándezSánchez, 1989). In Asia in the main moulds of the genera fungus genus, Rhizopus, Mucor, Actinomucor, Amylomyces, Neurospora and Monascus square measure employed in the manufacture of hard foods. In Europe, mould-ripened foods square measure primarily cheeses and meats, sometimes employing a Penicillium-species (Leistner, 1990). Manihot esculenta created by ferment cassava suspension was found to contain eubacteria, fungus genus and genus Penicillium spp [16]. because the predominant organisms (Ofuya & Akpoti, 1988). The micro-organisms gift during a thirteen hard food created in African country known as dawadawa once twenty four h of fermentation, preponderantly were eubacteria sp. with tiny numbers of (0,3%) staphylococci sp., once thirty six h hr eubacteria sp., thirty fourth staphylococci sp. and once forty eight h fifty six eubacteria sp. and forty second staphylococci sp [17]. (Odunfa & Komolafe, 1989). Indonesian tapé ketan, a sweet, bitter and alcoholic rice product, is created employing a starter culture containing moulds, yeasts and bacterium. once seventy two h of fermentation, the hydrogen ion concentration was three,5 whereas the biomass of the hyphae of the moulds was fifteen,3 mg/g and of the yeast three,3 mg/g. (Cook et al., 1991). In Okpiye, that could be a food seasoner ready by the fermentation of Prosopis africana seeds, many species of bacterium particularly Bacillus, B. licheniformis, B. megaterium, staphylococci stratum and genus Micrococcus spp. were found to be the foremost active organisms (Achi, 1992). In trahanas, a hard food ready in Balkan nation from a combination of milk and flour, streptococci lactis, streptococci diacetylactis, Leuconostoc cremoris, eubacterium lactis, eubacterium casei, eubacterium bulgaricus and eubacterium acidophilus were found to play the key role in manufacturing acid and aroma (Lazos et al., 1993) [18].

Nutritional value of fermented foods

Generally, a big increase within the soluble fraction of a food is ascertained throughout fermentation. the amount similarly as quality of the food proteins as expressed by biological worth, and sometimes the content of watersoluble vitamins is mostly accrued [19], whereas the antinutritional factors show a decline throughout fermentation (Paredes-López & Harry, 1988). Fermentation leads to a lower proportion of dry matter within the food and also the concentrations of vitamins, minerals and supermolecule seem to extend once measured on a dry weight basis (Adams, 1990). Single similarly as mixed culture fermentation of Pennisetum glaucum flour with yeast and lactobacilli considerably accrued the whole quantity of soluble sugars [20], reducing and non-reducing sugar content, with a synchronal decrease in its starch content (Khetarpaul & Chauhan, 1990). Combination of cookery and fermentation improved the nutrient quality of all tested sorghum seeds and reduced the content of antinutritional factors to a secure level as compared with alternative ways of process (Obizoba & Atii, 1991). Mixed culture fermentation of Pennisetum glaucum flour with Saccharomyces diastaticus, baker's yeast, true bacteria brevis and true bacteria fermentum was found to enhance its biological utilization in rats (Khetarpaul & Chauhan, 1991). Fermentation iatrogenic a big decrease in supermolecule and polymer contents of okara, that is Associate in Nursing insoluble residue obtained as a by-product within the manufacture of soymilk [21]. The hard okara on the opposite hand neither accrued PER nor the fourteen weight gain in rats (Guermani et al., 1992) compared to non-fermented samples. The edibility of starch in geographic region gram, cowpea and mung bean was accrued by fermentation. Cookery of those hard legumes additional accrued the starch edibility [22].

Health effects of fermented foods

One of the explanations for the increasing interest in soured foods is its ability to market the functions of the human system alimentarium during a range of positive ways in which. This specific contribution is named probiotic impact [23]. Already early in 1900, Elie Metchnikov discerned the employment of soured milks within the diet for interference of bound diseases of the digestive tube and promotion of healthy day to day life. Since then variety of studies have currently shown that the soured food product do have a positive impact on health standing in some ways [24]. The human enteric microbic flora is calculable to weigh regarding a thousand grams and will contain ten sixteen – ten seventeen colony forming units representing quite five hundred strains. For physiological functions, it will be thought of to be a specialised organ of the body with a good type of functions in nutrition, medical specialty and metabolism (Gustafsson, 1983) [25]. Studies on mice have shown that the native microorganisms within the abdomen square measure eubacterium, eubacteria and Torulopsis, whereas within the gut, ceacum and colon many totally different species (Bacteroides, Fusobacterium, moneran, eubacterium, etc.) be (Savage, 1983). The canal microflora in humans also is glorious to contain many species. although there's a good variation among people, the quantity of species and size of the population square measure sometimes unbroken stable in traditional healthy subjects [26]. There’s a relentless struggle in maintaining the fascinating balance seventeen and a dynamic equilibrium between microbic populations among the microorganism (Robinson & Samona, 1992). The anaerobic organisms, that come the gram negative enterobacteria by regarding ten 000 : one, square measure related to the enteric epithelial tissue limiting adherence of potential pathogens by effective colonosation (Van der Waaij et al., 1972; Nord & kager, 1984; Swank & Dietch, 1996) [27]. The steadiness of the enteric microflora is plagued by several factors together with dietary habits. Decrease within the range of anerobic bacterium is related to increase within the range of gram negative pathogens within the enteric tract and their translocation to extraintestinal tissues. Beneath traditional conditions the enteric wall prevents translocation of organisms each dead and living additionally as microbic product like toxins from the gut to the blood. However, in patients with general insult like starvation, shock, injury and infection or specific insult of the canal canal through inflammation, therapy or radiation [28], the gut membrane porousness are magnified resulting in translocation of microbes (Carrico & Meakin, 1986; Alexander et al., 1990; Wells, 1990; Kasravi et al., 1997). A soured foodstuff or live microbic food supplement that has useful impacts on the host by rising enteric microbic balance is mostly understood to own probiotic effect [29].

Food safety aspects of fermented foods

It has been calculable that quite thirteen million infants and kids below 5 years more matured die annually within the tropical regions of the planet. Once metastasis infections, looseness of the bowels diseases ar the most typical diseases and have the best negative impact upon the expansion of infants and young youngsters. The causes of looseness of the bowels have historically been ascribed to facility and sanitation (Motarjemi et al., 1993) [30]. Foods ready below unhealthful conditions and often heavily contaminated with infective organisms play a serious role in kid mortality through a mix of looseness of the bowels diseases, nutrient absorption, and deficiency disease. All food things contain microorganisms of various sorts and in several amounts. That microorganism that may dominate depends on many factors, and generally microorganisms at the start gift in terribly low numbers within the food, for instance carboxylic acid bacterium (LAB) [31], can number the opposite organisms inhibiting their growth. In distinction to hard meat, fish, dairy farm and cereal product, hard vegetables haven't been recorded as a major supply of microbic gastrointestinal disorder (Fleming & McFeeters, 1981) [32].

Materials and methods


Cereal grains

Commercial quality flour of seventieth extraction rate selected as "bagerivetemjöl" was obtained from the commercial flourmill Skånemöllan AB, Sweden. Wheat grains of the Kosack selection was kindly provided by the seed company Svalöv/Weibulls AB, Svalöv, Sweden. Tef grains of the selection were bought from the Bio-Diversity Institute of the national of Abyssinia, capital of Ethiopia, Ethiopia [33].

Test Microorganism

The check microorganism, E. coli strain NG7C, was obtained from the Medical biology Department, Lund University. The microorganism was isolated from a baby with diarrhea in New Guinea Media [34]

The media used for isolation of the microorganism from the chemical action whole grain wheat and whole grain tef flour suspension were Violet Red gall aldohexose Agar for E. coli and Rogosa agar for lactobacilli. Brain Heart Infusion Broth was utilized to keep up the check microorganism used for assaying [35].


Lactate commonplace forty mg/dl was obtained from alphabetic character. Organic acid analysis commonplace with zero, 8 μmol Na salt, 4,0 μmol Na turn, 8,0 μmol Na malate, 20,0 μmol Na succinate, twenty μmol Na formate and twenty,0 μmol Na acetate was obtained from Bio-Rad . All alternative chemicals utilized in this study were of analytical grade [36].


Preparation of flour

To obtain the tef and whole flour, the grains were cleansed by re motion 3 times in H2O, dried in an exceedingly aerated kitchen appliance at 50°C and polished in an exceedingly Tecator Cyclotec mill employing a 1-mm sieve. The flour was kept in an exceedingly closed plastic instrumentality at 4°C till it had been used for any experiments [37].


Fermentation was performed in an exceedingly suspension created with three hundred g of flour mixed with 600 cubic centimeter of 40°C heat water in an exceedingly 1-l beaker. To induce a regular mixture, 250 cubic centimeter of water was initial value-added to the flour and mixed, then 2 ulterior parts of seventy five cubic centimeter water was value-added with mix in between [38]. Finally, the remaining two hundred cubic centimeters was value-added along with the inoculant and completely mixed. The beaker was placed in an exceedingly water bathtub with a continuing temperature of 25°C or 35°C and also the fermentation was distributed while not stirring, in accordance with the standard home practice [39]. 3 completely different amounts were used, 1 g (»0,1%), ten g (»1%) and a hundred g (»10%) for back slopping. The fermentation was started while not inoculant as a spontaneous fermentation, then back slopping was performed at 84-h intervals. 3 consecutive backs loppings were created before the microorganism flora was tailored and also the system was thought of to be consistent (Nout et al., 1989) to permit samples being taken for analysis. The inoculant was taken from the previous batch when the liquid prime layer on top of the sediment has been decanted [40].


Samples were withdrawn at the start of fermentation and when each three, 6, 9, 12, 18, 24, forty eight and eighty four hours severally employing a syringe like sampling device, uptake regarding ten cubic centimeter of the sample regarding one cm on top of very cheap surface of the beaker. The samples for organic acids were quickly frozen by putting every of them in an exceedingly plastic instrumentality directly on a cold shelf of a electric refrigerator [41]. The frozen samples were unbroken at -18°C till they were used for any analysis. For testing which sort of carboxylic acid microorganism was gift within the tef fermentation, samples were taken at the tip of the fermentation method. These samples were unbroken cold at 4°C till they were used for any analysis [42].

Measurement of pH scale

The pH scale concentration} of the samples was measured victimization associate Orion expandable ion instrument Ea 920 associated an Orion Sure-Flow Ross pH-electrode [43].

Sample preparation for analysis of organic acids

The frozen sample was thawed to temperature, and just about one to two g in duplicates were weighed in to a centrifuge tube to that two hundred μl of acid (12,1 mg/ml) was value-added as internal normal along with seven cubic centimeter of H2O [44]. The content was homogenised and placed in an exceedingly water bathtub of 65°C for five minutes to forestall the carboxylic acid microorganism from continued the fermentation method throughout the analyses. The centrifuge tube with its contents was cooled to temperature in associate ice bathtub, neutralized to pH scale seven with zero,1 M hydroxide, and water was value-added to regulate the degree to ten cubic centimeter. The tube was then placed in associate supersonic bathtub for five min to facilitate the extraction of the organic acids, then centrifuged at 4000 rate (Johansson et al., 1995). The supernatant within the centrifuge tube was filtered through a 45-μm filter (Millipore HAWP 02500) and twenty μl of the filtrate was injected within the HPLC column [45].

Analysis of organic acids

Organic acids were associatealysed mistreatment an HPLC-apparatus consisting of a Pharmacia Pump P-3500, associate Aminex® HPX-87H column from Bio-Rad Laboratories and a Pharmacia Liquid activity Controller LCC five hundred. Because the mobile part zero,005 M acid was used at a flow of zero,6 ml/min. The column was unbroken immersed in a very water tub unbroken at 35°C [46]. For detection a Varian 2550 UV-detector at thirty four 410 nm set at vary zero,16 was used. Recordings were created on a Pharmacia Twochannel Recorder REC-482 and on the LCC five hundred. acid was used as internal normal and it didn't interfere with the separation of alternative acids. normal curves for carboxylic acid were planned mistreatment peak height and peak space given by the LCC five hundred, and peak height was chosen to be used because it showed the most effective correlation. All analysis was exhausted duplicates [47].

Titratable acidity

The titratable acidity was measured by titrating a combination of three g of sample and twenty seven cubic centimeter of H2O to hydrogen ion concentration eight.5 using 0.1 M caustic soda resolution (Kingamkono et al., 1994). The result was expressed as g drinkable acid/100 g sample, and planned against the results from HPLC-analysis. The trendline for the plot was established mistreatment Microsoft surpasses.

Measurement of the expansion of bacterium

For determination of the quantity of bacterium within the chemical action suspension, samples (~5 ml) were taken at completely different intervals from the highest (1 cm below the surface) and bottom (1 cm above) of the mixture. The samples (~1 g) were diluted with isosmotic solution (9 ml) for pour plate judge Rogosa agar (Oxoid, PM221) medium for carboxylic acid bacterium, and on violet red gall aldohexose agar (Oxoid, CM485) for E. coli. Carboxylic acid bacterium was incubated at 37°C for a amount of three days in associate anaerobic jar. E. coli was incubated at 37°C for a amount of 18-24 h [48].

Typing of the flora within the hard suspension

For writing the flora, samples were taken from the ultimate hard tef slurries and plated on Rogosa agar. Colonies were haphazardly picked, refined and hold on in cooling buffer (Ahrné et al., 1989). From every of those samples, 5 isolates were drawn for identification and subtyping. Identification and subtyping of eubacteria plantarum was done by haphazardly Implied Polymorphic DNA (RAPD) in step with the strategy delineate by Johansson et al, (Johansson et al., 1995) and by API fifty CH (API System, Montalieu, Vercieu, France) [49].

Design of E. coli experiments

The study contains 3 sets of experiments. The primary set of fermentation experiments were done to match the hydrogen ion concentration development and growth of carboxylic acid bacterium in spontaneous fermentation to back-slopping (1% and 10%) in whole grain thirty five flour suspension product of tef and wheat. The hydrogen ion concentration of the fermentation was measured at completely different levels to check if there was any distinction between prime surface and bottom layer. The second set of experiments was done to check the result of research lab fermentation on the expansion of E. coli accessorial to the sample. The hydrogen ion concentration development and numbers of research lab and E. coli were determined at completely different intervals. within the third set of experiments the hydrogen ion concentration was adjusted by adding carboxylic acid and acid to check the result of hydrogen ion concentration, quantity of carboxylic acid, and degree of dissociation of carboxylic acid [50].


The areas wherever the potency and yield of food fermentation processes are often inflated are: the choice or development of a lot of productive microorganism strains; the management and manipulation of culture conditions and therefore the improvement of product purification and concentration.

It is typically felt that ancient merchandise created at the little scale area unit unsanitary and unsafe. this can be typically true. But the case is commonly overdone. several hard foods area unit inherently safe owing to low wet contents or high acidity.

Quality control procedures area unit essential for the assembly of safe merchandise and contribute to the success of little food process businesses. applicable internal control procedures ought to be developed and enforced. These procedures ought to be developed with the processors United Nations agency should perceive and apply them.

Documentation of the normal strategies of food fermentation and analysis to spot improved strategies of production area unit nonsense if the results aren't disseminated to people who area unit doubtless to place them into follow. there's a danger of cryptic the fermentation method by enrobing it in theory.