Simultaneous lactic acid and xylitol production from vine trimming wastes

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 (Q_LA = 1.312 g L^?1 h^?1 and Y_LA/S = 0.93 g g^?1) and 27.5 g xylitol L^?1 (Q_Xylitol = 0.458 g L^?1 h^?1 and Y_Xylitol/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     

Production of detoxified sorghum straw hydrolysates for fermentative purposes

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     

Acid hydrolysis and fermentation of brewer's spent grain to produce xylitol

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 (Y_P/S = 0.70 g g⁻¹ and Q_P = 0.45 g dm⁻³ h⁻¹) were attained. Copyright © 2005 Society of Chemical Industry     

Use of waste materials for Lactococcus lactis development

BACKGROUND: Lactococcus lactis is an interesting microorganism with several industrial applications, particularly in the food industry. As well as being a probiotic species, L. lactis produces several metabolites with interesting properties, such as lactic acid (LA) and biosurfactants. Nevertheless, L. lactis is an especially demanding species since it has strong nutritional requirements, implying the use of complex and expensive culture media. RESULTS: The results showed the potential of L. lactis CECT‐4434 as a LA and biosurfactant producer. The economical cost of L. lactis cultures can be reduced by replacing the MRS medium by the use of two waste materials: trimming vine shoots as C source, and 20 g L^?1 distilled wine lees (vinasses) as N, P and micronutrient sources. From the hemicellulosic fraction, 14.3 g L^?1 LA and 1.7 mg L^?1 surfactin equivalent were achieved after 74 h (surface tension reduction of 14.4 mN m^?1); meanwhile, a simultaneous saccharification and fermentation process allowed the generation of 10.8 g L^?1 LA and 1.5 mg L^?1 surfactin equivalent after 72 h, reducing the surface tension by 12.1 units at the end of fermentation. CONCLUSIONS: Trimming vine shoots and vinasses can be used as alternative economical media for LA and cell‐bound biosurfactant production. Copyright © 2010 Society of Chemical Industry     

Production of fermentable media from vine‐trimming wastes and bioconversion into lactic acid by Lactobacillus pentosus

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 (Q_P = 0.844 g l^?1 h^?1, Y_P/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     

Improving downstream processes to recover tartaric acid,tartrate and nutrients from vinasses and formulation of inexpensive fermentative broths for xylitol production

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 (Q_{P, xylitol} = 0.232 g L^?1 h^?1) and products yields (Y_xylitol/S = 0.57 g g^?1) than fermentations carried out using commercial nutrients (Q_{P, xylitol} = 0.193 g L^?1 h^?1 and Y_xylitol/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     

Comparison of vacuum impregnation and soaking techniques for addition of the probiotic Lactobacillus acidophilus to minimally processed melon

This study aimed to evaluate the vacuum impregnation (VI) and soaking methods in the addition of Lactobacillus acidophilusLA‐3 to minimally processed melon (MPM). The melons were washed, sanitised in chlorine solution (200 mg L^?1), peeled and cutted into cubes. Lactobacillus acidophilusLA‐3 (1.4 × 10¹⁰ CFU g^?1) were added to the MPM through both techniques. The L. acidophilusLA‐3 count in MPM was similar to those commonly found in dairy products having probiotic claim, but VI was more efficient than soaking in maintaining the viability (8.61 and 7.98 Log CFU g^?1, respectively). The pH, acidity and soluble solids were not affected by probiotic culture and the incorporation technique; however, the VI affected the firmness of fruit. The MPM was within Brazilian standards for their microbiological characteristics. MPM may be used as a carrier of probiotic bacteria, being one more alternative for individuals who consume probiotic products.     

Detoxification of Aflatoxin B1 and M1 by Lactobacillus acidophilus and prebiotics in whole cow's milk

The detoxification ability of Lactobacillus acidophilus and prebiotics was evaluated by a Plackett‐Burman Design to examine the reduction of concentration and bioaccessibility of aflatoxin B₁ (AFB₁) and M₁ (AFM₁) in artificially contaminated whole cow's milk. Six variables were evaluated: AFB₁ (3.25–6.0 μg L^?1) or AFM₁ (1.0–2.0 μg L^?1) concentration; incubation time (0–6 h); and inulin, oligofructose, β‐glucan, and polydextrose concentrations (each between 0.00 and 0.75%). All runs achieved reductions of AFB₁ (13.53–35.53%) and AFM₁ (17.65–71.52%). Comparing with the positive control, the AFB₁ bioaccessibility ranged from 23.68 to 72.67% and for AFM₁ was 0%. The probiotic, isolated or combined with prebiotics, was efficient in mycotoxin reduction, while the combination of the two reduced the mycotoxin bioaccessibility. The best experimental condition was the highest concentration of AFB₁ (6.5 μg L^?1) and AFM₁ (2.0 μg L^?1), incubation time of 0 h and the addition of probiotic and inulin (0.75%).     

Xylitol bioproduction from wheat straw: hemicellulose hydrolysis and hydrolyzate fermentation

A 2² central composite design with five center points was performed to estimate the effects of temperature (120, 130 and 140 °C) and acid loading (100, 150 and 200 mg g^?1) on the yield of monomeric xylose recovery from wheat straw hemicellulose (Y_S/RM). Under the best hydrolysis condition (140 °C and 200 mg g^?1), a Y_S/RM of 0.26 g g^?1 was achieved. After vacuum concentration and detoxification by pH alteration and active charcoal adsorption, the hydrolyzate was used as source of xylose for xylitol bioproduction in a stirred tank reactor. A xylitol production of 30.8 g L^?1 was achieved after 54 h^?1 of fermentation, resulting in a productivity (Q_P) of 0.57 g L^?1 h^?1 and bioconversion yield (Y_P/S) of 0.88 g g^?1. The maximum specific rates of xylose consumption and xylitol production were 0.19 and 0.15 g g^?1 h^?1, respectively. Copyright © 2006 Society of Chemical Industry     

Effect of prebiotics on viability and growth characteristics of probiotics in soymilk

BACKGROUND: Soy products have attracted much attention lately as carriers for probiotics. This study was aimed at enhancing the growth of probiotics in soymilk via supplementation with prebiotics. RESULTS: Lactobacillus sp. FTDC 2113, Lactobacillus acidophilus FTDC 8033, Lactobacillus acidophilus ATCC 4356, Lactobacillus casei ATCC 393, Bifidobacterium FTDC 8943 and Bifidobacterium longum FTDC 8643 were evaluated for their viability and growth characteristics in prebiotic‐supplemented soymilk. In the presence of fructooligosaccharides (FOS), inulin, mannitol, maltodextrin and pectin, all strains showed viability exceeding 7 log₁₀ colony‐forming units mL^?1 after 24 h. Their growth was significantly (P < 0.05) increased on supplementation with maltodextrin, pectin, mannitol and FOS. Additionally, supplementation with FOS, mannitol and maltodextrin increased (P < 0.05) the production of lactic acid. Supplementation with FOS and maltodextrin also increased the α‐galactosidase activity of probiotics, leading to enhanced hydrolysis and utilisation of soy oligosaccharides. Finally, prebiotic supplementation enhanced the utilisation of simpler sugars such as fructose and glucose in soymilk. CONCLUSION: Supplementation with prebiotics enhances the potential of soymilk as a carrier for probiotics. Copyright © 2009 Society of Chemical Industry     

Encapsulation of probiotic Lactobacillus acidophilus by ionic gelation with electrostatic extrusion for enhancement of survival under simulated gastric conditions and during refrigerated storage

The probiotic Lactobacillus acidophilus was encapsulated in biodegradable and biocompatible capsules prepared by ionic gelation between phytic acid (PA) and chitosan (CS) with an electrostatic extrusion method. Calcium carbonate (CaCO₃) and starch were used as co‐encapsulants for improvement of capsule stability. Capsules were characterised and evaluated for survival of encapsulated L. acidophilus cells in simulated gastric fluid (SGF) and during refrigerated storage. Loading capacity values of PA‐CS capsules, PA‐CS‐starch capsules and PA‐CS‐CaCO₃ capsules were 8.20, 8.12 and 7.81 log CFU g^?1 of wet capsule, respectively. Capsules showed particle sizes of 1.3–1.5 mm and a uniform spherical shape. PA‐CS‐CaCO₃ capsules were the most stable vehicles for the protection of probiotic cells against acidic damage, particularly at pH 1.5 and pH 2. L. acidophilus cells from PA‐CS‐CaCO₃ capsules showed only a 0.64 log CFU reduction in numbers after 2 h in pH 1.5 SGF conditions. The numbers of L. acidophilus encapsulated in PA‐CS‐CaCO₃ capsules were decreased by only 0.69 log CFU g^?1, while PA‐CS capsules and PA‐CS‐starch capsule numbers were reduced by more than 1.45 log CFU g^?1 after 4 weeks at 4 °C. Addition of calcium carbonate to PA‐CS capsules provided protection against acid injury via antacid and buffering effects for encapsulation of L. acidophilus.     

Integral utilisation of barley husk for the production of food additives

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 (Q_P) = 2.077 g L^?1 h^?1 and product yield (Y_P/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 Q_P = 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     

Screening selected strains of probiotic lactic acid bacteria for their ability to produce biogenic amines (histamine and tyramine)

The aim of this study was to investigate the production of biogenic amines (BA), histamine and tyramine by some probiotic lactic acid bacteria (LAB). Fifteen strains representing six LAB species were screened qualitatively by growing them in a decarboxylase medium. Quantitative analysis was carried out by HPLC analysis with direct derivatization of acid extracts. Lactobacillus casei (TISTR 389) and Lactobacillus delbrueckii subsp. bulgaricus (TISTR 895) were found to produce BA. The highest levels of histamine (1820.9 ± 3.5 mg L^?1) and tyramine (5486.99 ± 47.6 mg L^?1) formation were observed for the TISTR 389 strain, while TISTR 895 produced only histamine (459.1 ± 0.63 mg L^?1) in the decarboxylase broth. Biogenic amine potential was not observed for the Lactobacillus acidophilus, Lactobacillus lactis subsp. lactis, Lactococcus lactis subsp. lactis, and Lactobacillus plantarum strains studied. This study confirmed that BA formation is strain dependent and not related to the species. Therefore, careful screening for amino acid decarboxylase activity is recommended before selecting LAB as appropriate starter or probiotic strains in food and dairy industry.     

Preparation and properties of probiotic concentrated yoghurt (labneh) fortified with conjugated linoleic acid

Milk of high conjugated linoleic acid (CLA) level (1.25 g per 100 g milk fat) was produced by inclusion of fish oil and rousted soy bean in the ration of Holstein cows as compared to 0.55 g per 100 g milk fat in the milk of animals receiving control diet. Milk of normal (control) and high CLA content (treatment) was spray‐dried. Labneh was made from 20 g L^?1 reconstituted milk using 3 mL per 100 mL yoghurt starter and 2 mL per 100 mL of probiotic cultures of Lactobacillus casei or Lactobacillus acidophilus. The control (C) and high CLA (T) labneh were analysed chemically and microbiologically, and their viscosities were determined during cold storage for 15 days. The fat content of labneh of high CLA was less than that of the control, but the total solids (TS) were unaffected by the CLA level. Labneh made with Lb. acidophilus had lower TS and higher acidity, exopolysaccharides and acetaldehyde contents and viscosity than that made with the use of Lb. casei. Labneh from the different treatments retained high counts of the added probiotic (>10⁸ cfu g^?1) throughout the storage period. The storage period had significant effects on all parameters determined.     

Comparison of the performances of different fermentation strategies on cell growth and bacteriocin production by Lactobacillus curvatus CWBI‐B28

The dynamics of cell growth and bacteriocin production by Lactobacillus curvatus CWBI‐B28 in modified De Man/Rogosa/Sharp (mMRS) broth with various concentrations of glucose and complex nitrogen source (CNS; peptone, yeast extract and meat extract) was investigated in flask fermentations and in a laboratory fermentor using batch and fed‐batch cultivations. In fed‐batch fermentation the rate of feeding of the reactor with the substrates was either maintained constant (0.12 L h^?1) or varied exponentially as a function of time. The results showed that both cell growth and bacteriocin activity were influenced by changes in the concentrations of glucose and CNS. Optimal growth and bacteriocin activity were obtained in mMRS broth containing 40 g L^?1 glucose and 40 g L^?1 CNS (mMRS_40/40). A bacteriocin titre of 4266 AU mL^?1 and a cell count of 8.7 log colony‐forming units (cfu) mL^?1 were recorded when this medium was used for cultivation. In batch fermentation using the same medium, a higher cell count (9.5 log cfu mL^?1) and twice as much bacteriocin as in flask fermentation were produced. The highest bacteriocin titre (8533 AU mL^?1) was obtained with fed‐batch fermentation at an exponentially varying rate of feeding. Bacteriocin activity and cell dry mass did not always correlate. Copyright © 2007 Society of Chemical Industry     

Evaluation of the conditions of carotenoids production in a synthetic medium by Sporidiobolus salmonicolor (CBS 2636) in a bioreactor

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 (Y_P/X) was 238 μg carotenoids/g cells, whereas Y_P/S (substrate to product yield) was 41.3 μg g^?1. The specific growth rate (μ_x) 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.     

Broad bean and pea by‐products as sources of fibre‐rich ingredients: potential antioxidant activity measured in vitro

BACKGROUND By‐products generated during the processing of plant food can be considered a promising source of dietary fibre as a functional compound. The dietary fibre composition, soluble sugars and antioxidant activity of the extractable polyphenols of pea and broad bean by‐products have been analysed in this study. RESULTS: Total dietary fibre using AOAC methods plus hydrolysis (broad bean pod: 337.3 g kg^?1; pea pod: 472.6 g kg^?1) is higher (P < 0.05) in both by‐products than with the Englyst method (broad bean pod: 309.7 g kg^?1; pea pod: 434.6 g kg^?1). The main monomers are uronic acids, glucose, arabinose and galactose in broad bean pods. However, pea pods are very rich in glucose and xylose. The soluble sugars analysed by high‐performance liquid chromatography in both by‐products have glucose as the most important component, followed by sucrose and fructose. The ferric reducing antioxidant power (broad bean pod: 406.4 µmol Trolox equivalents g^?1; pea pod: 25.9 µmol Trolox equivalents g^?1) and scavenging effect on 2,2‐diphenyl‐1‐picrylhydrazyl radical (EC₅₀ of broad bean pod: 0.4 mg mL^?1; EC₅₀ of pea pod: 16.0 mg mL^?1) were also measured. CONCLUSIONS: Broad bean and pea by‐products are very rich in dietary fibre, particularly insoluble dietary fibre and their extractable polyphenols demonstrate antioxidant activity. Therefore they might be regarded as functional ingredients. Copyright © 2011 Society of Chemical Industry     

Production, purification and characterisation of polysaccharides from Pleurotus ostreatus with antitumour activity

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, P_max = 0.935 ± 0.018 g L^?1 day^?1, µ_max = 0.218 ± 0.02 day^?1, Y_EP/X = 0.040 ± 0.0015 g g^?1 and Y_IP/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     

Low‐field NMR: A tool for studying protein aggregation

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     

Influence of fermentation with different lactic acid bacteria and in vitro digestion on the change of phenolic compounds in fermented kiwifruit pulps

The present study aimed to evaluate the effect of fermentation and gastrointestinal digestion of three kinds of fermented kiwifruit pulps with different Lactobacillus (Lactobacillus plantarum, Lactobacillus acidophilus and Lactobacillus casei). The changes in bioactive substances (total phenolic acid, total flavonoid, vitamin C and the viable count), antioxidant capacity (DPPH, ABTS, hydroxyl radical and superoxide anion radical scavenging activity) and phenolic profiles (protocatechuic acid, protocatechualdehyde, chlorogenic acid, caffeic acid and p-coumaric acid) were detected. The result showed, compared to non-fermented kiwifruit pulp, fermentation with LP and LA had higher content of TPA, TF and V_C, as well as antioxidant capacity. Fermentation with LP and the content of protocatechualdehyde, p-coumaric acid and chlorogenic acid were increased. However, after digestion, LP showed more effect in maintaining the content of antioxidants, antioxidant capacity and the viable count rather than LA. During digestion, the content of protocatechualdehyde and p-coumaric acid was increased in fermented samples compared with non-fermented samples. Overall, compared with LA and LC, LP is more suitable for the fermentation of kiwifruit pulp.