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1.
Fermentation conditions and microorganisms were determined, based on acid production, glucose concentration as carbohydrate source. Inoculation levels to obtain a stable shrimp waste silage were also determined. Shrimp waste ensilation was an efficient method of preservation, allowing the recovery of chitin and another added-value products such as pigments, proteins and enzymes. From the various lactic acid bacteria tested, Lactobacillus pentosus and Lactobacillus sp. (B2) were the best lactic acid producers, although small quantities of acetic acid were detected in samples inoculated with Lactobacillus pentosus. Therefore B2 was chosen for the analysis of glucose consumption as well as for the determination of optimum inoculation levels. The best results were obtained at 10% (w/w wet basis) and 5% (v/w wet basis) respectively. Presence of starters and initial glucose concentration were critical factors in the fermentation of shrimp waste. High initial glucose and starter concentrations reduced the time and increased the amount of lactic acid produced. The fermentation pattern changed during ensilation from hetero to homofermentative. Shrimp waste ensilation prevented the growth of spoilage microorganisms keeping their microbial counts steady and pH values within the acid region.  相似文献   

2.
Microbial ecology of fermenting plant materials   总被引:8,自引:0,他引:8  
Abstract The lactic acid fermentation of plant materials is presented from an ecological perspective emphasizing microbial interactions and their influence on the production of fermented plant foods and silage. The plant lactic acid bacteria are discussed in terms of evolution; epiphytic function; physical distribution within fermented material; substrates and products; microbial sequences in fermentation; interactions among species; pure culture fermentation; and starter culture development.  相似文献   

3.
AIMS: Aflatoxin B(1) (AFB(1)) is a mycotoxin which is known to frequently contaminate poorly stored food products destined for human consumption. This study was carried out to investigate the potential activity of lactic acid fermentation in reducing AFB(1) level in fermented maize meal products. METHODS AND RESULTS: Maize meal was spiked with 60 mug g(-1) AFB(1) and fermented, with or without starter culture, for 4 days at 25 degrees C. Unbound AFB(1) in solution and the pH of the media were monitored daily. A significant decrease (P < 0.05) in the level of unbound AFB(1) was observed (75% in the fourth day). Simultaneously, a progressive decrease in the pH of the media from 6.5 to 3.1 was also observed. AFB(1) was below the detection limit in commercial fermented porridge (amahewu) samples. Cytotoxicity tests on AFB(1)-spiked fermented extracts showed that those with a starter culture were comparatively less toxic (30-36%) than those with no added starter culture (24-30%). However, this difference was not significant (P > 0.05). CONCLUSIONS: These results indicate that lactic acid fermentation can significantly reduce the concentration of AFB(1) in maize to trace levels. However, the safety of fermented products has not been well studied, as the mechanism of AFB(1) removal is not well understood. SIGNIFICANCE AND IMPACT OF THE STUDY: Natural fermentation may potentially reduce exposure to natural toxins occurring in food.  相似文献   

4.
Four sausage batters (17.59% beef, 60.67% pork, and 17.59% pork fat) were inoculated with two commercial starter culture organisms (>7 log(10) CFU/g Pediococcus pentosaceus and 6 log(10) CFU/g Staphylococcus carnosus) and a five-strain cocktail of nonpathogenic variants of Escherichia coli O157:H7 to yield 6 to 7 log(10) CFU/g. Microencapsulated allyl isothiocyanate (AIT) was added to three batters at 500, 750, or 1,000 ppm to determine its antimicrobial effects. For sensory analysis, separate batches with starter cultures and 0, 500, or 750 ppm microencapsulated AIT were produced. Sausages were fermented at < or =26 degrees C and 88% relative humidity (RH) for 72 h. Subsequently sausages were dried at 75% RH and 13 degrees C for at least 25 days. The water activity (a(w)), pH, and levels of starter cultures, E. coli O157:H7, and total bacteria were monitored during fermentation and drying. All sausages showed changes in the initial pH from 5.57 to 4.89 and in a(w) from 0.96 to 0.89 by the end of fermentation and drying, respectively. Starter culture numbers were reduced during sausage maturation, but there was no effect of AIT on meat pH reduction. E. coli O157:H7 was reduced by 6.5 log(10) CFU/g in sausages containing 750 and 1,000 ppm AIT after 21 and 16 days of processing, respectively. E. coli O157:H7 numbers were reduced by 4.75 log(10) CFU/g after 28 days of processing in treatments with 500 ppm AIT, and the organism was not recovered from this treatment beyond 40 days. During sensory evaluation, sausages containing 500 ppm AIT were considered acceptable although slightly spicy by panelists.  相似文献   

5.
Aims:  Investigating the influence of an added starter culture on the properties of fermented liquid pig feed.
Methods and Results:  Diets of cereal grain blended with wet wheat distillers' grain that were either not inoculated (WWDG), inoculated with a silage starter culture at start (WWDGsc1) or at start and at each backslopping (replacement of 80% the content with fresh mixture, simulating feed outtake, WWDGsc5) were fermented for 5 days, followed by 5 days of daily backslopping. Numbers of undesirable micro-organisms (enterobacteria, moulds) were reduced in all fermentations; particularly enterobacteria in the starter culture inoculated diets. Lactobacillus plantarum present in the starter culture became dominant in diets WWDGsc1 and WWDGsc5. However, Lactobacillus panis that was dominating WWDG was also abundant in WWDGsc1 and WWDGsc5. Yeast populations were not influenced by the starter culture, with Pichia fermentans dominating all fermentations. All diets had similar chemical characteristics with the exception of a significant increase of all tested organic acids in WWDGsc5.
Conclusions:  The addition of a starter culture influences the bacterial population in fermented liquid feed, but there is also a strong impact of the flora already present in the feed ingredients. The yeast population is not influenced by adding a lactic acid bacteria (LAB) starter culture. A consortium of LAB and yeast strains adapted to the fermentation should be used as starter culture.
Significance and Impact of the Study:  The results suggest that it is possible to influence the current unpredictable and spontaneous process of feed fermentation when appropriate starter cultures are used. For this purpose, LAB and yeasts with desirable characteristics should be isolated.  相似文献   

6.
Lactic fermentation of shrimp waste on solid substrates was studied as a means of preservation for chitin recovery. Shrimp wastes were fermented in 100-g flasks with varying levels of inoculation with lactobacilli as well as different types and levels of carbohydrate. Sucrose was selected as the carbohydrate source in further experimental work due to its better acid production potential as compared to lactose and milk whey powder. Lactic acid fermentation was scaled-up from 2 to 30 kg in column reactors using geometric similarity as the scale-up criterion. The pH rapidly decreased to less than 5.0, allowing preservation of wastes for at least 3 months. During ensilation, deproteinisation and demineralisation were observed. Chitin obtained from the silage was treated with acid and alkali for mineral and protein removal.  相似文献   

7.
Lactic acid fermentation was evaluated as a method to preserve abattoir waste for use in fur animal diets. The method used involved grinding, acidifying to pH 5–5.2 by formic acid and propionic acid, addition of 6% molasses as a carbohydrate source and a starter culture of Lactobacillus plantarum. Fermentation was completed after 2–3 days at 25°C. The final pH of the fermented product was 3.8–4.1.

Storage experiments revealed satisfactory stability. The fermented products could be kept for weeks at room temperature (20°C) and for months in a cold room (4°C).

The amino acid composition of the 4 types of abattoir waste tested was not significantly changed by fermentation. Digestibility studies with mink revealed slight, but significant (P < 0.05), effects of fermentation. The digestibility of cystine and threonine was reduced and that of glycine and proline increased.

Two types of fermented abattoir waste were investigated in 2 long-term feeding experiments with mink and blue foxes. In the mink trial, diets with 10 or 20% fermented abattoir waste supported normal reproduction, kit mortality and body growth. In one experiment, there was a significant reduction in mink kit body weights with 20%, but not with 10% fermented abattoir waste in the diet. In the fox trial, litter sizes and kit viability tended to improve with 20% fermented abattoir waste, while kit body weights were unaffected. It is concluded that fermentation could be an acceptable process for the preservation of abattoir waste intended for the feeding of fur animals.  相似文献   


8.
In this work, Lactobacillus plantarum BP04 was employed as starter culture in dining-hall food waste storage with different inoculant levels at 0, 2 and 10% (v/w) to suppress the outgrowth of pathogenic and spoilage bacteria. Inoculation by Lactobacillus plantarum BP04 was effective in accelerating pH drop and reducing the growth period of enterobacteria to 9, 7 and 2 days, corresponding to inoculant levels at 0, 2 and 10% (v/w). Increasing inoculum levels were found to inhibit the growth of Lactobacillus brevis and Leuconostoc lactis. HPLC analysis revealed that lactic acid was the predominant organic acid during the treatment of dining-hall food waste. Its concentration varied among the fermented processes reflecting variations of microbial activity in the fermented media.  相似文献   

9.
The influence of pH adjusted with lactic acid or HCl or sodium chloride concentration on survival or growth of Escherichia coli O157:H7 in Trypticase soy broth (TSB) was determined. Studies also determined the fate of E. coli O157:H7 during the production and storage of fermented, dry sausage. The organism grew in TSB containing less than or equal to 6.5% NaCl or at a pH of 4.5 to 9.0, adjusted with HCl. When TSB was acidified with lactic acid, the organism grew at pH 4.6 but not at pH 4.5. A commercial sausage batter inoculated with 4.8 x 10(4) E. coli O157:H7 per g was fermented to pH 4.8 and dried until the moisture/protein ratio was less than or equal to 1.9:1. The sausage chubs were then vacuum packaged and stored at 4 degrees C for 2 months. The organism survived but did not grow during fermentation, drying, or subsequent storage at 4 degrees C and decreased by about 2 log10 CFU/g by the end of storage. These studies reveal the importance of using beef containing low populations or no E. coli O157:H7 in sausage batter, because when initially present at 10(4) CFU/g, this organism can survive fermentation, drying, and storage of fermented sausage regardless of whether an added starter culture was used.  相似文献   

10.
A Box-Bhenken design with four variables (shrimp shell concentration (SSC), glucose concentration, incubation time and inoculum size) and three levels was used for the determination of the deproteinization and demineralization efficiencies in fermented shrimp shells by Pseudomonas aeruginosa A2. The fermentation variables were selected in accordance with Plackett-Burman design. Maximum demineralization of 96%, with about 89% of protein removal occurs under the following conditions: SSC 50 g/l, glucose 50 g/l, 5 days and inoculum of 0.05 OD. This environment friendly method (biological treatment) can be considered as an effective pretreatment to produce a high-quality chitin.  相似文献   

11.
The kinetics in batch culture of the acetone butanol fermentation by Clostridium acetobutylicum is compared on glucose, xylose, and mixtures of both sugars. The fastest initial growth and transition from an acid to a solvent metabolism occurs on glucose, with a final 62 g/L glucose conversion. On xylose, an initial slower growth rate and a longer metabolic transition result in higher cellular and acids concentration, thus in a level of fermented sugar limited to 47 g/L. Batch fermentations on mixtures of glucose and xylose show that both sugars can be fermented, with a higher rate for glucose. However, xylose fermentation is inducible and inhibited at glucose level above 15 g/L. Mixtures of glucose and xylose yield the highest amount of fermented sugars, up to 68 g/L, as a result of both a fast metabolic transition on glucose and a strong acid reconsumption on xylose. In all cases, solvent production is triggered at a total acid concentration between 4 and 5 g/L, whereas the final inhibition of the fermentation takes place at a total butanol and acid concentration between 18 and 20 g/L.  相似文献   

12.
The underlying method for obtaining a beta-carotene-rich carotenoid-protein preparation and exopolysaccharides is the associated cultivation of the carotenoid-synthesizing lactose-negative yeast strain Rhodotorula rubra GED8 with the yogurt starter culture (Lactobacillus bulgaricus 2-11 + Streptococcus thermophilus 15HA) in whey ultrafiltrate (45 g lactose/l) with a maximum carotenoid yield of 13.37 mg/l culture fluid on the 4.5th day. The chemical composition of the carotenoid-protein preparation has been identified. The respective carotenoid and protein content is 497.4 microg/g dry cells and 50.3% per dry weight, respectively. An important characteristic of the carotenoid composition is the high percentage (51.1%) of beta-carotene (a carotenoid pigment with the highest provitamin A activity) as compared to 12.9% and 33.7%, respectively, for the other two individual pigments--torulene and torularhodin. Exopolysaccharides (12.8 g/l) synthesized by the yeast and lactic acid cultures, identified as acid biopolymers containing 7.2% glucuronic acid, were isolated in the cell-free supernatant. Mannose, produced exclusively by the yeast, predominated in the neutral carbohydrate biopolymer component (76%). The mixed cultivation of R. rubra GED8 with the yogurt starter (L. bulgaricus 2-11 + S. thermophilus 15HA) in ultrafiltrate under conditions of intracellular production of maximum amount of carotenoids and exopolysaccharides synthesis enables combined utilization of the culture fluid from the fermentation process.  相似文献   

13.
Staphylococcus aureus 196E added to a beef sausage containing starter culture and 0.5 to 2.0% glucose and incubated at 35 degrees C was unable to grow when plated on tryptic soy agar (TSA) containing 7.5% NaCl. The injury, presumed to be due to the lactic acid produced during fermentation, was more pronounced at the lower concentrations of glucose (and lower acid levels). In the absence of glucose and/or starter culture, no injury was observed. When sausages containing S. aureus injured by fermentation at 35 degrees C were incubated at 5 degrees C, the counts on TSA (measures both injured and uninjured cells) and TSA containing 7.5% NaCl (measures uninjured cells only) remained constant; however, upon reincubation of the cold-stored sausage at 35 degrees C, the staphylococcus counts on TSA and TSA containing 7.5% NaCl and were similar to the counts of S. aureus present in fermenting sausages that had never been subjected to 5 degrees C. The demonstration of acid injury indicated that the injury phenomenon must be considered when determining numbers of viable S. aureus in fermented sausages.  相似文献   

14.
Injury to Staphylococcus aureus during sausage fermentation.   总被引:1,自引:1,他引:0       下载免费PDF全文
Staphylococcus aureus 196E added to a beef sausage containing starter culture and 0.5 to 2.0% glucose and incubated at 35 degrees C was unable to grow when plated on tryptic soy agar (TSA) containing 7.5% NaCl. The injury, presumed to be due to the lactic acid produced during fermentation, was more pronounced at the lower concentrations of glucose (and lower acid levels). In the absence of glucose and/or starter culture, no injury was observed. When sausages containing S. aureus injured by fermentation at 35 degrees C were incubated at 5 degrees C, the counts on TSA (measures both injured and uninjured cells) and TSA containing 7.5% NaCl (measures uninjured cells only) remained constant; however, upon reincubation of the cold-stored sausage at 35 degrees C, the staphylococcus counts on TSA and TSA containing 7.5% NaCl and were similar to the counts of S. aureus present in fermenting sausages that had never been subjected to 5 degrees C. The demonstration of acid injury indicated that the injury phenomenon must be considered when determining numbers of viable S. aureus in fermented sausages.  相似文献   

15.
In the presented study, ensiling of discard fish by acidification or fermentation was evaluated. Klunzinger’s ponyfish which is a discard fish was used for the production of fish silage by acidification (3% formic acid for Method FA; 1.5% formic and 1.5% sulphuric acid for Method FASA) and fermentation (Lactobacillus plantarum for Method LP and Streptococcus thermophilus for Method ST). The chemical, microbiological and nutritional properties of the differently preserved fish silages were estimated during a storage period of 60 d at ambient temperature. Compared to the raw material, a slight increase in saturated fatty acids and a slight decrease in polyunsaturated fatty acids were observed in all silages. At the end of the storage period, the aerobic bacteria counts after applying Methods FA, FASA, LP and ST amounted to 2.35, 2.39, 5.77 and 5.43 log cfu/g, respectively. The analysis of thiobarbituric acid revealed that acidification of silages accelerated the lipid oxidation. Nine biogenic amines were found in raw fish and different silages. The initial histamine concentration in raw fish was 0.17 mg/100 g and in all silages it remained at low levels during the storage period. The initial tyramine content was found to be 1.56 mg/100 g in raw fish and increased significantly in all silages. The increase of the tyramine content in fermented silages was considerably higher than in acidified silages (23–48 mg/100 g and 5–10 mg/100 g, respectively). It can be concluded that acidified or fermented fish silage should be considered as potential feed component for animals because of its high nutritional value and appropriate microbiological and chemical quality.  相似文献   

16.
L(+)-lactic acid production was investigated using an enzymatic hydrolysate of waste office automation (OA) paper in a culture of the filamentous fungus Rhizopus oryzae. In 4 d culture, 82.8 g/l glucose, 7 g/l xylose, and 3.4 g/l cellobiose contained in the hydrolysate were consumed to produce 49.1 g/l of lactic acid. The lactic acid yield and production rate were only 0.59 g/g and 16.3 g/l/d, respectively, only 75% and 61% of the results from the glucose medium. The low production rate from waste OA hydrolysate was elucidated by trials using xylose as the sole carbon source; in those trials, the lactic acid production rate was 7.3 g/l/d, only 28% that of glucose or cellobiose. The low lactic acid yield from waste OA hydrolysate was clarified by trials using artificial hydrolysates comprised of 7:2:1 or 7:1:2 ratios of glucose:cellobiose:xylose. For both, the lactic acid production rate of 17.4 g/l/d matched that of waste OA paper, while the lactic acid yield was similar to that of the glucose medium. This indicates that the production rate may be inhibited by xylose derived from hemicellulose, and the yield may be inhibited by unknown compounds derived from paper pulp.  相似文献   

17.
Four sausage batters (17.59% beef, 60.67% pork, and 17.59% pork fat) were inoculated with two commercial starter culture organisms (>7 log10 CFU/g Pediococcus pentosaceus and 6 log10 CFU/g Staphylococcus carnosus) and a five-strain cocktail of nonpathogenic variants of Escherichia coli O157:H7 to yield 6 to 7 log10 CFU/g. Microencapsulated allyl isothiocyanate (AIT) was added to three batters at 500, 750, or 1,000 ppm to determine its antimicrobial effects. For sensory analysis, separate batches with starter cultures and 0, 500, or 750 ppm microencapsulated AIT were produced. Sausages were fermented at ≤26°C and 88% relative humidity (RH) for 72 h. Subsequently sausages were dried at 75% RH and 13°C for at least 25 days. The water activity (aw), pH, and levels of starter cultures, E. coli O157:H7, and total bacteria were monitored during fermentation and drying. All sausages showed changes in the initial pH from 5.57 to 4.89 and in aw from 0.96 to 0.89 by the end of fermentation and drying, respectively. Starter culture numbers were reduced during sausage maturation, but there was no effect of AIT on meat pH reduction. E. coli O157:H7 was reduced by 6.5 log10 CFU/g in sausages containing 750 and 1,000 ppm AIT after 21 and 16 days of processing, respectively. E. coli O157:H7 numbers were reduced by 4.75 log10 CFU/g after 28 days of processing in treatments with 500 ppm AIT, and the organism was not recovered from this treatment beyond 40 days. During sensory evaluation, sausages containing 500 ppm AIT were considered acceptable although slightly spicy by panelists.  相似文献   

18.
Five experiments were conducted to either ferment fresh shrimp or crab waste with molasses, molasses and bacterial inoculant, or to preserve it with salt. Experiment 1 was a 4 × 2 factorial arrangement. Crab waste was combined with 0, 5, 10, or 15% liquid molasses, and stored in mini-silos (15 l) with or without lids for 14 days. The addition of molasses slightly decreased pH and offensive odors; mini-silo temperatures without lids were higher than those with lids. Experiment 2 was a 5 × 2 factorial arrangement designed to enhance fermentation. Fresh shrimp waste was combined with 0, 10, 15, 20, or 25% dry molasses and 0 or 1.0 × 108 colony forming bacteria/g inoculant and ensiled for six days. As the level of molasses increased, dry matter and lactic acid increased but, the pH, crude protein, ammonia acetic, butyric, and propionic acid concentrations decreased. Significant molasses by inoculant interactions occurred which were highly variable for each acid. Evidence of fermentation was supported by production of lactic acid at all levels of molasses. The pH decreased from 7.7 in the untreated waste to an average of 7.4 for the 10, 15 and 20% molasses treated wastes to 6.8 in the 25% molasses treated waste. The high pH was an indication that the waste may be unstable with longer storage (> 6 days). Therefore, in Experiment 3, designed as a 2 × 2 factorial arrangement, shrimp waste treated with 15 and 20% molasses, with or without inoculant was ensiled for 21 days to test stability. By day 21, shrimp waste had deteriorated as indicated by a mean pH of 7.5, low lactic acid, and high butyric acid concentration, an unacceptable odor, and the presence of mold on the surface of the samples.In Experiments 4 and 5, shrimp or crab waste was combined with salt at 0, 2.5, 5.0, 7.5, 10.0, and 12.5%. Increasing levels of salt decreased crude protein percent, ammonia concentration, and lactic and volatile fatty acids while increasing the pH and improving the acceptability of the odors in both the shrimp and crab wastes. Treatment of crustacean waste with 7.5% or greater salt was more effective at preserving crude protein and minimizing odor than either dry or liquid molasses.  相似文献   

19.
This study investigated butanol fermentation using glucose and culture broth containing butyrate from the butyrate fermentation of a brown alga, Laminaria japonica. Prior to the use of the biologically-produced butyrate, the initial glucose in tryptone-yeast extract acetate (TYA) medium was first optimized for butanol fermentation using Clostridium saccharoperbutylacetonicum N1-4 ATCC 27021T. Then, a commercially-acquired (synthetic) butyrate was supplemented to the TYA medium containing the optimal glucose concentration (around 30 and 60 g/L). According to the experimental results, the highest butanol carbon yield (0.580 C-mol/C-mol) was obtained from the fermentation of 36.65 g/L glucose and 7.29 g/L synthetic butyrate. Fermentation of a similar amount of glucose (32.28 g/L) in the absence of butyrate gave a butanol carbon yield of 0.402 C-mol/C-mol. For the experiment with fermented butyrate, a 100 g/L biomass of brown alga was fermented by Clostridium tyrobutyricum ATCC 25755 and the culture broth containing butyrate was used to prepare TYA medium after removing the bacterial cells. Fermentation using the synthetic butyrate and the biologically-produced butyrate (4.95 g/L) gave a comparable butanol concentration (13.23 g/L) and butanol carbon yield (0.513 C-mol/C-mol). Overall, this study proved that the addition of fermented butyrate from brown alga fermentation could be an effective way to improve butanol production. Furthermore, the reuse of spent medium and the absence of rigorous purification of the broth containing butyrate would lower the production cost of the fermentation.  相似文献   

20.
In vitro antioxidant activity of liquor from fermented shrimp biowaste   总被引:5,自引:0,他引:5  
Shrimp waste was fermented using lactic culture and the separated fermented liquor was lyophilized. In vitro antioxidant activities of the lyophilized powder were evaluated with respect scavenging of different radicals and quenching of generated singlet oxygen. The sample showed strong radical scavenging and singlet oxygen quenching in a dose dependent manner (p<0.001). The sample exhibited 40% scavenging of DPPH radical at 1.0mg/ml concentration while the ABTS radical scavenging was 95% even at 0.5mg/ml concentrations. Hydroxyl radical scavenging activity as measured by chemiluminescence technique showed 80% scavenging and peroxyl radical scavenging was 65% at 1.0mg/ml concentration. The singlet oxygen quenching ability of the powder was 68.3% at 1.0mg/ml concentration. The sample was found to contain low molecular weight proteins. The formation of peptides and amino acids during hydrolysis of shrimp waste protein during fermentation is expected to be responsible for the antioxidant activity. In addition as the product also contains carotenoids, it can be used as an ingredient in aquaculture feed formulations for beneficial effects.  相似文献   

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