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1.
Beatriz Rivas Ana Torrado Sandra Rivas Ana Belén Moldes José Manuel Domínguez 《Journal of the science of food and agriculture》2007,87(8):1603-1612
Hemicellulosic hydrolyzates from vineshoot trimmings obtained by dilute sulfuric acid hydrolysis were evaluated for xylitol production by Debaryomyces hansenii NRRL Y‐7426. Bioconversion was not efficient, however, since a mixture of products (mainly ethanol) was achieved. Taking into account that hexoses (such as glucose or mannose) can inhibit xylose metabolism by repression and inactivation of the xylose transport system or catabolic enzymes and that these hemicellulosic hydrolyzates are characterized by a high glucose concentration, a novel technology was developed, sequentially transforming glucose into lactic acid by Lactobacillus rhamnosus followed by fermentation of xylose into xylitol by Debaryomyces hansenii after L. rhamnosus removal by microfiltration. Optimal conditions were achieved using detoxified concentrated hemicellulosic hydrolyzates, after CaCO3 addition in both stages of fermentation and using nitrogen purges after sampling in order to reduce the oxygen dissolved. Under these conditions 31.5 g lactic acid L?1 (QLA = 1.312 g L?1 h?1 and YLA/S = 0.93 g g?1) and 27.5 g xylitol L?1 (QXylitol = 0.458 g L?1 h?1 and YXylitol/S = 0.53 g g?1) were produced. Finally, lactic acid was selectively recovered using the resin Amberlite IRA 400 (0.0374 g of lactic acid g?1 of dry resin), allowing a further recovery of xylitol by sequential stages of adsorption, concentration, ethanol precipitation, concentration and crystallization to obtain food‐grade xylitol according to a developed process. Copyright © 2007 Society of Chemical Industry 相似文献
2.
José Manuel Salgado Noelia Rodríguez Sandra Cortés José Manuel Domínguez 《Journal of the science of food and agriculture》2010,90(13):2168-2177
BACKGROUND: Vinasses, the main liquid wastes from the distillation process of grape marc and wine lees, are acidic effluents with high organic content, including acids, carbohydrates, phenols, and unsaturated compounds with high chemical oxygen demand, biological oxygen demand and solid concentrations. These wastes can be revalued to provide additional benefits when they are employed as feedstock of some compounds including tartaric acid, calcium tartrate and economic nutrients for the elaboration of fermentable broths. RESULT: This study attempts to recover tartaric acid and calcium tartrate from vinasses. All the tartaric acid initially solubilised was recovered in both processes. The residual streams can be successfully employed as economic nutrients for the xylose to xylitol bioconversion, achieving higher global volumetric productivities (QP, xylitol = 0.232 g L?1 h?1) and products yields (Yxylitol/S = 0.57 g g?1) than fermentations carried out using commercial nutrients (QP, xylitol = 0.193 g L?1 h?1 and Yxylitol/S = 0.55 g g?1 respectively). CONCLUSION: Tartaric acid can be recovered from vinasses in the form of tartaric acid crystals and calcium tartrate. The residual streams generated in the process can be used as economic nutrients for the production of xylitol by D. hansenii. Copyright © 2010 Society of Chemical Industry 相似文献
3.
Revalorisation of vine trimming wastes using Lactobacillus acidophilus and Debaryomyces hansenii 总被引:1,自引:0,他引:1
Oscar M Portilla Beatriz Rivas Ana Torrado Ana B Moldes José M Domínguez 《Journal of the science of food and agriculture》2008,88(13):2298-2308
BACKGROUND: Mild acid treatments of vine‐shoot trimmings result in the hydrolysis of hemicellulosic sugars that can be utilised by Lactobacillus acidophilus CECT‐4179 (ATCC 832) and Debaryomyces hansenii NRRL Y‐7426 as carbon sources to obtain food additives. Since the high content of glucose in these hydrolysates reduces the effective bioconversion of xylose into xylitol by D. hansenii, the use of Lactobacillus acidophilus, one of the main probiotic species, allows this problem to be solved by the selective consumption of glucose. In order to use both sugars (glucose and xylose), hemicellulosic vine‐shoot trimming hydrolysates can be sequentially fermented by both micro‐organisms. RESULTS: It was found that, in the first step, L. acidophilus generated almost exclusively lactic acid (32.7 g of lactic acid L?1, QLA = 1.363 g L?1 h?1, YLA/S = 0.72 g g?1) by homofermentative degradation of sugars (mainly glucose), and in the second step, the remaining hemicellulosic sugars were transformed primarily into xylitol by Debaryomyces hansenii (31.3 g of xylitol L?1, QXylitol = 0.708 g L?1 h?1, YXylitol/S = 0.66 g g?1). Furthermore, L. acidophilus proved to be a strong cell‐bounded biosurfactant producer. Cell extracts were able to reduce the surface tension (ST) of PBS in 18 mN m?1 units. Lactobacillus acidophilus cells showed no difference in viability before or after PBS extraction of biosurfactants, achieving values of 0.9 × 109 colony‐forming units (CFU) mL?1 in both cases. CONCLUSIONS: These results have made a serious contribution to the re‐evaluation of a useless and pollutant residue, producing a wide range of natural food additives. Copyright © 2008 Society of Chemical Industry 相似文献
4.
Eunice Valduga Pihetra Oliveira Tatsch Lídia Tiggemann Jamile Zeni Rosicler Colet João Marcos Cansian Helen Treichel Marco Luccio 《International Journal of Food Science & Technology》2009,44(12):2445-2451
This work studied the cultivation conditions for the production of carotenoids by Sporidiobolus salmonicolor (CBS 2636) in a bioreactor. A Plackett–Burman design was used for the screening of the most important factors, followed by a complete second order design, to maximise the concentration of total carotenoids. The maximum concentration of 3425.9 μg L?1 of total carotenoids was obtained in a medium containing 80 g L?1 glucose, 15 g L?1 peptone and 5 g L?1 malt extract, with an aeration rate 1.5 vvm, 180 r.p.m., 25 °C and an initial pH of 4.0. Fermentation kinetics showed that the maximum concentration of total carotenoids was reached after 90 h of fermentation. Carotenoid bio‐production was partially associated with cell growth. The specific carotenoid production (YP/X) was 238 μg carotenoids/g cells, whereas YP/S (substrate to product yield) was 41.3 μg g?1. The specific growth rate (μx) was 0.045 h?1. The highest cell and total carotenoid productivity were 0.19 g L?1 h?1 and 56.9 μg L?1 h?1, respectively. 相似文献
5.
Solange I Mussatto Inês C Roberto 《Journal of the science of food and agriculture》2005,85(14):2453-2460
The hemicellulosic fraction of brewer's spent grain (BSG) was hydrolysed with diluted acid under different conditions of liquid/solid ratio (8–12 g g−1), sulfuric acid concentration (100–140 mg g−1 dry matter) and reaction time (17–37 min) in order to produce a liquor with a large amount of xylose and good fermentability to produce xylitol. Results showed that all the evaluated reaction conditions were able to hydrolyse xylan and arabinan with efficiencies higher than 85.8 and 95.7% respectively, and even under the mildest reaction condition a considerable amount (92.7%) of the hemicellulosic fraction could be extracted. The hydrolysates presented different fermentabilities when used as fermentation media for xylitol production by Candida guilliermondii yeast, owing to the differences in their composition. Based on statistical analysis, the best condition for BSG acid hydrolysis was the use of a liquid/solid ratio of 8 g g−1, 100 mg H2SO4 g−1 dry matter and a reaction time of 17 min. Under this condition a high extraction efficiency of hemicellulosic sugars (92.7%) and good fermentation results (YP/S = 0.70 g g−1 and QP = 0.45 g dm−3 h−1) were attained. Copyright © 2005 Society of Chemical Industry 相似文献
6.
José M Cruz Ana B Moldes Guadalupe Bustos Ana Torrado José M Domínguez 《Journal of the science of food and agriculture》2007,87(6):1000-1008
A new and effective chemical–biotechnological process for the global utilisation of barley husk (obtained from the spent grains in the brewing process) is reported. With the proposed process the three main components of the lignocellulosic residue (cellulose, hemicellulose and lignin) are utilised. A first treatment with sulfuric acid (pre‐hydrolysis) allowed the solubilisation of hemicelluloses to give xylose and glucose‐containing liquors (suitable to make fermentation media for the continuous lactic acid (LA) production with L. pentosus) and a solid phase containing cellulose and lignin. In this set of experiments, a maximum volumetric productivity (QP) = 2.077 g L?1 h?1 and product yield (YP/S) = 0.62 g g?1 were obtained for a dilution rate of 0.01 h?1. The solid residues from pre‐hydrolysis were treated with NaOH in order to increase their cellulase digestibility, and dissolve the lignin content. The cellulose residue was used as substrates for lactic acid production by simultaneous saccharification and fermentation (SSF) in media containing Trichoderma reesei cellulases and Lactobacillus rhamnosus cells using the complete MRS broth or a cheaper medium. In both cases similar LA concentrations and volumetric productivities were achieved (P = 73.4–71.0 g L?1 and QP = 1.28–1.25 g L?1 h?1, respectively), where P is LA concentration. The lignin solution obtained after the alkaline treatment was extracted with ethyl acetate in order to obtain the phenolic components. The extract obtained at pH 3 showed three times more antioxidant activity than the one extracted at pH 12.8, with an EC50 of 1.396 g L?1 for pH 3 and 4.604 g L?1 for pH 12.8. The best extracts showed twice antioxidant activity than BHT. Copyright © 2007 Society of Chemical Industry 相似文献
7.
Guadalupe Bustos Ana Beln Moldes Jos Manuel Cruz Jos Manuel Domínguez 《Journal of the science of food and agriculture》2004,84(15):2105-2112
Trimmings of vineshoots, an agricultural waste with little use, were hydrolysed with dilute sulphuric acid (1–5%) in order to obtain sugar solutions suitable as fermentation media. The operational conditions for hydrolysis were selected on the basis of both the generation of hemicellulosic sugars (mainly xylose) and glucose and the concentrations of reaction byproducts affecting fermentation (furfural, hydroxymethylfurfural and acetic acid). Hemicellulosic hydrolysates were supplemented with nutrients and fermented with Lactobacillus pentosus, without any previous detoxification stage, to produce lactic acid. Under the best operational conditions assayed (3% H2SO4 and 15 min), 21.8 g lactic acid l?1 was produced (QP = 0.844 g l?1 h?1, YP/S = 0.77 g g?1), which represents a theoretical yield of 99.6%. Acetic acid was the primary byproduct formed from xylose, at about 25% of the lactic acid level. Copyright © 2004 Society of Chemical Industry 相似文献
8.
Erisema Sepúlveda‐Huerta Simn J Tellez‐Luis Virgilio Bocanegra‐García Jos A. Ramírez Manuel Vzquez 《Journal of the science of food and agriculture》2006,86(15):2579-2586
Sorghum straw can be hydrolysed to obtain monosaccharide solutions, mainly containing xylose. The usual biotechnological application of xylose is its bioconversion to xylitol. The global process from straw to xylitol can give an added value to the sorghum straw. The process has the following sequential steps: reduction of size, acid hydrolysis, neutralization, detoxification, fermentation, recovery and purification. This work deals with the optimization of the detoxification process of sorghum straw hydrolysates with activated charcoal. The variables evaluated were pH (1–5), contact time (20–60 min) and activated charcoal charge (20–33 g kg?1). Mathematical models were obtained through a factorial experimental design. The models suggest that optimal conditions for detoxification are pH 1, contact time of 29 min and a charcoal charge of 33 g kg?1. These conditions allowed hydrolysates with 54.2 g xylose L?1, 13.5 g glucose L?1, 12 g arabinose L?1, 0.2 g furfural L?1 and 0.0 g acetic acid L?1 to be obtained. The results suggest that performing the detoxification step before the neutralization step gave the best outcome. Fermentations by Candida parapsilosis NRRL Y‐2315 were performed and it was confirmed that the treated hydrolysate is suitable for xylitol production, yielding up to 17 g L?1 of this polyol. Copyright © 2006 Society of Chemical Industry 相似文献
9.
Masahiro Miura Keitaro Yokono Housei Miyamoto Masakazu Aoyama Kiyoshi Tada Jun-ichi Horiuchi Yasuo Kojima Chikara Sakai Masahiro Nakahara 《Holz als Roh- und Werkstoff》2010,68(2):139-142
To prepare a substrate for microbial conversion of xylose into xylitol, the culm of Sasa kurilensis was hydrolysed with dilute sulphuric acid. A fermentable substrate with a relatively high xylose concentration (21.9?g?L?1) was obtained by hydrolysis with 2% sulphuric acid with a liquid to solid ratio of 10?:?1 at 121°C for 1?h. During hydrolysis at elevated temperatures, some undesirable byproducts were also generated, such as degradation products of solubilized sugars and lignin, which are potential inhibitors of microbial metabolism. These compounds were successfully removed from the hydrolysate by treatment with a commercially available activated charcoal (30?g?L?1 dose). 相似文献
10.
Silva S Martins S Karmali A Rosa E 《Journal of the science of food and agriculture》2012,92(9):1826-1832
BACKGROUND: Mushroom polysaccharides play an important role in functional foods because they exhibit biological modulator properties such as antitumour, antiviral and antibacterial activities. The present study involved the production, purification and characterisation of intracellular and extracellular free and protein‐bound polysaccharides from Pleurotus ostreatus and the investigation of their growth‐inhibitory effect on human carcinoma cell lines. RESULTS: Several fermentation parameters were obtained: batch polysaccharide productivities of 0.013 ± 8.12 × 10?5 and 0.037 ± 0.0005 g L?1 day?1 for intracellular and extracellular polysaccharides respectively, a maximum biomass concentration of 9.35 ± 0.18 g L?1, Pmax = 0.935 ± 0.018 g L?1 day?1, µmax = 0.218 ± 0.02 day?1, YEP/X = 0.040 ± 0.0015 g g?1 and YIP/X = 0.014 ± 0.0003 g g?1. Some polysaccharides exhibited superoxide dismutase (SOD)‐like activity of 50‐200 units. Fourier transform infrared analysis of the polysaccharides revealed absorption bands characteristic of such biological macromolecules. Cytotoxicity assays showed that both intracellular and extracellular polysaccharides exhibited antitumour activity towards several tested human carcinoma cell lines in a dose‐dependent manner. CONCLUSION: The polysaccharides of P. ostreatus exhibited high SOD‐like activity, which strongly supports their biological effect on tumour cell lines. The extracellular polysaccharides presented the highest antitumour activity towards the RL95 carcinoma cell line and should be further investigated as an antitumour agent. Copyright © 2012 Society of Chemical Industry 相似文献
11.
《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2013,30(5):608-615
The principal aim of this study was to estimate the formation of fumonisins (FB1 and FB2), moniliformin (MON), and ergosterol (ERG) by Fusarium oxysporum and Fusarium proliferatum, while the formation of beauvericin (BEA) was estimated by the latter Fusarium species only. Moreover, the effect of temperature on the biosynthesis of mycotoxins was also evaluated. Fumonisins were formed by F. proliferatum, with the highest yield at 18°C (720.0–1976.6 µg g?1 for FB1, 74.2–670.8 µg g?1 for FB2) and only by three of four F. oxysporum strains at a very low level (0.02–4.77 µg g?1 for FB1, 0.02–2.15 µg g?1 for FB2). The amount of MON formed by F. proliferatum was the highest (p < 0.001) at 32°C (3056.87 µg g?1), while MON biosynthesis by F. oxysporum was lower 227.54 µg g?1 (p < 0.001). BEA was produced by F. proliferatum with the highest level at 25°C (p < 0.001). ERG–recognized as an indicator of fungal biomass development and as a consequence of mycotoxin formation–was found at the highest concentration at a biosynthesis temperature of 25°C for F. proliferatum and F. oxysporum (p < 0.001). 相似文献
12.
Yun-zhi Zou Kai Qi Xiang Chen Xiao-ling Miao Jian-Jiang Zhong 《Journal of Bioscience and Bioengineering》2010,109(2):149-152
Xylitol production from xylose by a self-isolated furfural and 5-hydroxymethyl furfural assimilating Pichia guilliermondii was studied under oxygen limitation. An extremely low initial volumetric oxygen transfer coefficient (0.075 h− 1) was found most favorable to the xylitol production with yield of 0.61 g g− 1. Related enzymes activities were also investigated and discussed. 相似文献
13.
Linda Indrawati Richard L Stroshine Ganesan Narsimhan 《Journal of the science of food and agriculture》2007,87(12):2207-2216
Low‐field nuclear magnetic resonance (NMR) spin–spin relaxation (T2) measurements were used to study the denaturation and aggregation of β‐lactoglobulin (β‐LG) solutions of varying concentrations (1–80 g L?1) as they were heated at temperatures ranging from ambient up to 90 °C. For concentrations of 1–10 g L?1, the T2 of β‐LG solutions did not change, even after heating to 90 °C. A decrease in T2 was only observed when solutions having higher concentrations (20–80 g L?1) were heated. Circular dichroism (CD) spectroscopy and fluorescence tests using the dye 1‐anilino‐8‐naphthalene sulfonate (ANS) on 0.2 and 1 g L?1 solutions, respectively, indicated there were changes in the protein's secondary and tertiary conformations when the β‐LG solutions reached 70 °C and above. In addition, dynamic light scattering (DLS) showed that protein aggregation occurred only at concentrations above 10 g L?1 and for heating at 70 °C and above. The hydrodynamic radius increased as T2 decreased. When excess 2‐mercaptoethanol was added, the changes in both T2 and the hydrodynamic radius followed the same trend for all β‐LG protein concentrations between 1 and 40 g L?1. These observations led to the conclusion that the changes in T2 were due to protein aggregation, not protein unfolding. Copyright © 2007 Society of Chemical Industry 相似文献
14.
《Food Biotechnology》2013,27(3):343-361
Abstract The production of β-carotene from a synthetic medium by Blakeslea trispora in fed-batch culture was investigated. A maximum β-carotene concentration of 85.0?mg?L?1 with productivity of 0.16?mg?L?1?h?1 and specific β-carotene production rate of 0.01?mg?g?1?h?1 was obtained by feeding the cells constantly with olive oil, cottonseed oil, soybean oil, antioxidant, and low concentration of growth factors at feeding rate of 4.2?mL?h?1 from the beginning of the fermentation. In this case, the fed-batch culture supported high values of biomass dry weight (11.0?g?L?1) and sugar utilization (0.976?g?g?1). The morphology of the fungus was studied during growth in fed-batch fermentation system using an image analysis system. Zygospores are the morphological forms, which are responsible for the production of the pigment. The highest percentage of zygospores (11.44%) was correlated with the highest percentage of intracellular β-carotene (0.72%) in the total biomass dry weight. Moreover, high percentages of vacuolated hyphae, evacuated cells, and degenerated hyphae of the microorganism were observed. This was due to the formation of high amount of H2O2 by exposure of the microorganism to high dissolved oxygen concentration. 相似文献
15.
Maruf Ahmed Akter Mst. Sorifa Jong Bang Eun 《International Journal of Food Science & Technology》2010,45(4):726-732
Effect of pretreatments with 1 w/v% sodium hydrogen sulphite (NaHSO3) and 1 w/v% calcium chloride (CaCl2) and drying temperatures (55, 60 and 65 °C) on sweet potato flour were investigated. Flour treated with CaCl2 had higher amounts of ascorbic acid and β‐carotene (10.61–12.54 and 3.26–3.46 mg 100 g?1 wet basis, respectively) than that treated with NaHSO3 (9.47–11.47 and 3.05–3.43 mg 100 g?1 wet basis, respectively). Total phenolic content and water absorption index (wet basis) were highest at 65 °C when treated with NaHSO3 (10.44 mg 100 g?1 and 2.49 g g?1 respectively) and CaCl2 (9.52 mg 100 g?1 and 2.85 g g?1 respectively). Swelling capacity (wet basis) was highest at 60 °C when treated with CaCl2 (2.96 g g?1) whereas when treated with NaHSO3 (2.85 g g?1) it was highest at 55 °C. Freeze‐dried samples treated with NaHSO3 had higher lightness and total phenolic content while CaCl2‐treated samples had higher β‐carotene and ascorbic acid. The results showed that good quality flour could be produced after soaking in CaCl2 and dried at 65 °C. 相似文献
16.
Annapurna S Kamat Madhusudanan P Nair 《Journal of the science of food and agriculture》1995,69(4):415-422
Cells of Listeria monocytogenes ATCC 35152 were sensitive to gamma irradiation in phosphate buffer, pH 7.00 (D10, dose required for 10% survival—0.15 kGy) at 0–5°C. The cells showed higher radiation survival when irradiated under frozen condition, with a D10 of 0.3 kGy. The protection offered by shrimp/chicken/kheema homogenates (100 g litre?1) was evidenced by even higher D10 values (0.5 kGy) at both 0–5°C and cryogenic temperature. Boneless chicken meat samples were artificially inoculated with L monocytogenes ATCC 35152 cells at low (5 × 103) colony-forming unit (cfu) g?1 and high (5 × 106 cfu g?1) concentrations and irradiated at 1, 3, 4, 6 kGy doses under cryogenic conditions. The efficacy of the radiation process was evaluated by detecting L monocytogenes during storage at 2–4°C in the irradiated samples. These studies, when repeated with three other serotypes of L monocytogenes, clearly suggested the need for a dose of 3 kGy for elimination of 103 cfu cells of L monocytogenes g?1 from air-packed frozen chicken meat. 相似文献
17.
David G Chamberlain 《Journal of the science of food and agriculture》1989,46(2):129-138
Perennial ryegrass (Lolium perenne L) was ensiled in laboratory silos after addition of glucose or xylose at rates of 0, 25, 35 and 45 g kg?1 fresh grass. In addition, an inoculum of Lactobacillus plantarum, supplying 106 organisms g?1 fresh grass, was applied to all treatments. Silos were opened after 7, 21 and 100 days and the silage was subjected to chemical and microbiological analysis. AH silages were well fermented with pHs between 3·60 and 3·70 and low NH3-N concentrations (<95 g kg?1 total nitrogen) and an absence of butyric acid. Glucose was virtually completely consumed within 21 days but 0·30–0·50 of the xylose doses remained after 100 days. Lactic acid concentrations were not increased by the addition of sugars, but the glucose treatments were associated with very high concentrations of ethanol, 60–100 g kg?1 DM, and the xylose additions produced very high concentrations of acetic acid, 60–135 g kg?1 DM. Most(>0·80) of the glucose that disappeared could be accounted for in ethanol formation but the xylose consumed could be accounted for only if the lactic acid produced in its fermentation was metabolised further to acetic acid; indeed, for the two higher doses of xylose, the concentrations of lactic acid were reduced from the control value of 177 g kg?1 DM to 140 and 120 g kg?1 DM, respectively. The results indicate that the provision of extra sugar, as hexose or pentose, allows yeasts to assume a more prominent role in the fermentation with consequent wasteful fermentation of sugars. Furthermore, the suggestion is that xylose may indirectly, via a stimulation of lactate-assimilating yeasts, encourage further metabolism of lactic acid to acetic acid. 相似文献
18.
Yongliang Zhuang Yufeng Zhang Liping Sun 《International Journal of Food Science & Technology》2012,47(6):1279-1285
The contents of total dietary fibre (TDF), soluble dietary fibre (SDF), insoluble dietary fibre (IDF) and functional properties of fibre‐rich powders (FRP) from pitaya peels with different particle size (FRP80, FRP140 and FRP250) were determined. Results showed that FRP140 had higher TDF (79.37%) and SDF (33.07%) with a balanced ratio of SDF/IDF (1:1.32) and higher water‐holding capacity (54.20 g g?1), swelling capacity (50.63 mL g?1), oil‐holding capacity (2.65 g g?1) and glucose dialysis retardation index (62.83% at 60 min), compared with FRP80 and FRP250. Therefore, physiochemical properties of FRP140 were further investigated. SDF of FRP140 mainly contained rhamnose (4.95%) and galactose (1.98%), with 9.45% galacturonic acid, while IDF dominantly contained xylose (4.76%) and galactose (3.42%), with 18.54% klason lignin. Total phenolic content was 7.75 mg g?1 and mainly composed of salicylic acid (0.98 mg g?1) and protocatechuic acid (0.45 mg g?1). Furthermore, FRP140 showed significant reducing power, DPPH‐scavenging activity and nitrite‐scavenging ability. 相似文献
19.
Daniel Rico Ana Belen Martín‐Diana Jesus M Frías Gary TM Henehan Catherine Barry‐Ryan 《Journal of the science of food and agriculture》2006,86(13):2179-2188
The effects of three treatments, 1 mg L?1 ozone at 18–20 °C, 15 g L?1 calcium lactate (CLac) at 50 °C and a combination thereof, were compared on fresh‐cut lettuce over 10 days of refrigerated storage. Respiration rate, browning and texture were examined as main quality indicators. The use of ozone produced a significantly (P < 0.05) higher oxygen decline than the use of CLac (from day 3 to day 10). At the end of storage, CLac (alone or combined with ozone) samples had higher oxygen content (~9%) than ozone samples (~6%). Enzymatic activity decreased significantly (P < 0.05) in ozone samples. Polyphenol oxidase activity in fresh‐cut lettuce treated with ozone (alone or combined with CLac) showed lower values on day 1 (<2500 units g?1) and at the end of storage (<3000 units g?1) than CLac samples (4000–4800 units g?1). Ozone also reduced peroxidase activity to ~300 units g?1 after treatment. Finally, pectin methylesterase activity was also reduced with ozone, showing a negative effect on textural properties. Data suggested that CLac maintained quality markers better than treatments with ozone and ozone/CLac combination over 10 days of storage. Copyright © 2006 Society of Chemical Industry 相似文献
20.
BACKGROUND: Aflatoxins are a group of mycotoxins that cause serious chronic disease outbreaks and contaminate several food products such as corn and its by‐product, corn gluten. The aim of the current study was to evaluate the effect of hydrochloric acid (HCl) on aflatoxin B1 (AFB1) degradation in contaminated corn gluten under different HCl concentrations, hydrolysis temperatures and hydrolysis times. RESULTS: During the wet milling process the highest AFB1 level (45.68 µg kg?1) (37.86%) was found in corn gluten fraction. Treatment with 1 mol L?1 HCL at 110 °C resulted in degradation of AFB1 by 27.6% (33.07 µg kg?1) after 4 h and reached 42.5% (26.26 µg kg?1) after 8 h. Increasing HCl concentration from 1 to 3 mol L?1 HCl resulted in increased degradation of AFB1, while complete degradation occurred in the presence of 5 mol L?1 HCl after 4 h at 110 °C. Meanwhile, half‐life time of AFB1 was recorded after 2 h at 100 °C and was < 2 h at 110 °C in the presence of 3 mol L?1 HCl. CONCLUSION: It could be demonstrated that the manufacture of hydrolyzed vegetable protein is a suitable method for decontamination of aflatoxin in highly contaminated grains, especially gluten fractions. The hydrolysis reaction could be considered in terms of first‐order reaction kinetics of AFB1 degradation. Copyright © 2010 Society of Chemical Industry 相似文献