Robustness of Lactobacillus plantarum starters during daily propagation of wheat flour sourdough type I

This study aimed at investigating the robustness of selected sourdough strains of Lactobacillus plantarum. Seven strains were singly used as sourdough type I starters under daily back-slopping propagation (ten days) using wheat flour. Cell numbers of presumptive lactic acid bacteria varied slightly (median values of 9.13–9.46 log cfu g⁻¹) between and within started sourdoughs, as well as the acidifying activity (median values of 1.24–1.33). After three days also the control sourdough (unstarted) had the same values. As shown by RAPD-PCR analysis, five (DB200, 3DM, G10C3, 12H1 and LP20) out of seven strains maintained elevated cell numbers (ca. 9 log cfu g⁻¹) throughout ten days. The other two strains progressively decreased to less than 5 log cfu g⁻¹. As identified by partial sequencing of 16S rRNA and recA genes, L. plantarum (11 isolates), pediococci (7), Lactobacillus casei (3) and Lactobacillus rossiae (2) dominated the flour microbiota. Monitoring of lactic acid bacteria during sourdough propagation was carried out by culture dependent approach and using PCR-DGGE (Denaturing Gradient Gel Electrophoresis). Except for the sourdough started with L. plantarum LP20, in all other sourdoughs at least one autochthonous strain of L. plantarum emerged. All emerging strains of L. plantarum showed different RAPD-PCR profiles. L. rossiae and Pediococcus pentosaceus were only found in the control and sourdough started with strain 12H1. The characterization of the catabolic profiles of sourdoughs (Biolog System) showed that sourdoughs containing persistent starters behaved similarly and their profiles were clearly differentiated from the others. One persistent strain (DB200) of L. plantarum and Lactobacillus sanfranciscensis LS44, previously shown to be persistent ( Siragusa et al., 2009), were used as the mixed starter to produce a wheat flour sourdough. Both strains cohabited and dominated during ten days of propagation.     

Probiotic potential of Lactobacillus strains with anti-allergic effects from kimchi for yogurt starters

Lactobacillus strains were isolated from kimchi and investigated for their potential use for probiotic yogurt starters. Two of the isolated strains have over 90% survival rate to artificial gastric acid (pH 2.5, 1% pepsin) and artificial bile acid (0.3% oxgall). These strains were identified as Lactobacillus plantarum by 16S rRNA sequencing, and named as L. plantarum SY11 and L. plantarum SY12. The known carcinogenic enzyme, β-glucuronidase was not produced by L. plantarum SY11 and L. plantarum SY12. These 2 strains were found to be resistant to several antibiotics and strongly adhered to intestinal cells. Antiallergic effect of L. plantarum SY11 and L. plantarum SY12 was demonstrated using nitric oxide (NO) and cytokine production. L. plantarum SY11 and L. plantarum SY12 were capable of significantly decreasing NO production, and reduced T helper 2-associated cytokines, cyclooxygenase-2, tumor necrosis factor-α, and inducible nitric oxide synthase compared to control. Yogurt samples produced using L. plantarum SY11 and L. plantarum SY12 did not show significant differences in microbiological, physicochemical, and sensory properties compared with yogurt sample produced using commercial strain. Therefore, these two strains could be used as probiotic yogurt starters with antiallergic effects.     

Microbiological,physicochemical and rheological properties of fermented soymilk produced with exopolysaccharide (EPS) producing lactic acid bacteria strains

Growth of Lactobacillus plantarum 70810, Lactobacillus rhamnosus 6005 and a commercial yogurt starter culture in soymilk was investigated in the present study. It was found that the fermented soymilk using L. plantarum 70810 had significantly higher viable cell counts, water holding capacity (WHC, 88.27%), apparent viscosity (1840.35 mPa s) and exopolysaccharide (EPS) amount (832.15 mg/L) than the other two starter cultures in soymilk. Direct observation of microstructure in fermented soymilk indicated that the network structures of EPS-protein could improve the texture of fermented soymilk. Considering that the beneficial effects of L. plantarum 70810 in fermented soymilk, volatile compounds in fermented soymilk were further identified. Then the growth and fermentation characteristics of L. plantarum 70810 including changes in viable cell counts, pH, titratable acidity, apparent viscosity and EPS production during storage were investigated. In comparison to original soymilk base, the concentrations of the characteristic flavor compounds for fermented soymilk using L. plantarum 70810 increased, whereas hexanal, 2-pentylfuran and 2-pentanone in relation to beany flavor of soymilk decreased. In addition, fermented soymilk using L. plantarum 70810 maintained high viable cell count (>10⁸ cfu/mL), apparent viscosity (966.43 mPa s) and amounts of EPS (635.49 mg/mL) during storage at 4 °C for 21 days.     

Brewing of glucuronic acid-enriched apple cider with enhanced antioxidant activities through the co-fermentation of yeast (Saccharomyces cerevisiae and Pichia kudriavzevii) and bacteria (Lactobacillus plantarum)

Co-fermentation using yeast (Saccharomyces cerevisiae and Pichia kudriavzevii) and the bacteria (Lactobacillus plantarum) as starters isolated from spontaneous sourdough was conducted for the brewing of glucuronic acid (GlcA)-enriched apple cider. The concentration of GlcA in the apple cider co-fermented for 14 d with commercial S. cerevisiae and L. plantarum was 37.7 ± 1.7 mg/mL while a concentration of 62.8 ± 3.1 mg/mL was recorded for fermentation with P. kudriavzevii and L. plantarum, which was higher than the corresponding single yeast fermentation. The co-fermented apple cider revealed higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of 171.67 ± 0.79 µg trolox equivalents (TE)/mL using P. kudriavzevii and L. plantarum, compared to the control (143.89 ± 7.07 µg TE/mL) just using S. cerevisiae. Thus, the co-fermentation of S. cerevisiae and L. plantarum and P. kudriavzevii and L. plantarum provided a new strategy for the development of GlcA-enriched apple cider with enhanced antioxidant capacity.     

Pressure-resistant acclimation of lactic acid bacteria from a natural fermentation product using high pressure

Twenty colonies of Pediococcus acidilactici, Lactobacillus brevis, Lactiplantibacillus plantarum and Latilactobacillus curvatus were isolated from fermentation broth of pickled pepper by using MRS agar. The strains were acclimated using high pressure from 300 to 400 MPa for 1 to 5 min. For one generation of acclimation, the survived cells after first high pressure treatment were then activated by culturing on MRS agar for two days for the next high pressure treatment. After acclimation for 30 generations, the survival ratio of L. plantarum and L. curvatus was increased by 138 and 1222 times at 400 MPa for 1 and 3 min, respectively. Weibull model could appropriately fit the survival curves of L. plantarum and L. curvatus treated by high pressure. The time to the first decimal reduction of these two strains after acclimation was 3.5 and 1.8 times, respectively, longer than before acclimation at 300 MPa. From electron microscopy photographs, the acclimated L. curvatus was more curved, smaller and its cell wall was thicker than the unacclimated L. curvatus. After HPP treatment, L. plantarum and L. curvatus have higher cell integrity, smoother cell surface, more uniform protoplasm and smaller cavities in the cell protoplasm compared with unacclimated strains, suggesting that high pressure acclimation introduced some modification to bacteria intrinsic structures and increased their pressure resistance. Moreover, the fermentation performance including glucose utilization capacity and lactic acid production of the acclimated L. curvatus was respectively improved by 9.6% and 9.4% at 37 °C for 24 h in MRS medium.     

Edible methylcellulose-based films containing fructo-oligosaccharides as vehicles for lactic acid bacteria

The goal of this work was to investigate the physicochemical properties of methylcellulose (MC) based films as stabilizers of two strains of lactobacilli: Lactobacillus delbrueckii subsp. bulgaricus CIDCA 333 and Lactobacillus plantarum CIDCA 83114. The incorporation of 3% w/v fructo-oligosaccharides (FOS) into the MC film formulation improved the viability of L. delbrueckii subsp. bulgaricus CIDCA 333 after film preparation. L. plantarum CIDCA 83114 was intrinsically more resistant as no viability loss was observed upon preparation of the films in the absence of FOS.Scanning electronic microscopy images also showed a good incorporation of microorganisms without affecting the homogeneity of the films. FTIR spectroscopy provided structural information about the bacteria-loaded films. Water sorption isotherms showed an impervious behavior at low a_w but on exceeding 0.7 of a_w the film started to dissolve and form syrup, causing a drastic drop of bacterial viability (log N/N₀ ≤ − 5). Dynamic mechanical analysis (DMA) demonstrated that the incorporation of microorganisms into the MC films had no effect on vitreous transition temperatures. FOS incorporated into the MC films had a plasticizing effect.Microorganism-loaded films were stored at relative humidities (RH) ranging from 11 to 75%. Both strains could be stored at 11% RH for 90 days. At 33 and 44% RH L. delbrueckii subsp. bulgaricus CIDCA 333 could be stored up to 15 days and L. plantarum CIDCA 83114 up to 45 days. At 75% RH only L. plantarum CIDCA 83114 could be equilibrated (log N/N₀: − 2.05 ± 0.25), but CFU/g films were undetectable after 15 days of storage.The results obtained in this work support the use of MC films containing FOS as a good strategy to immobilize lactic acid bacteria, with potential applications in the development of functional foods.     

The effect of Lactobacillus buchneri 40788 or Lactobacillus plantarum MTD-1 on the fermentation and aerobic stability of corn silages ensiled at two dry matter contents

Whole-plant corn was harvested at 33 (normal) and 41% (moderately high) dry matter (DM) and ensiled in quadruplicate 20-L laboratory silos to investigate the effects of Lactobacillus buchneri 40788 (LB) or L. plantarum MTD-1 (LP) alone, or in combination, on the fermentation and aerobic stability of the resulting silage. Aerobic stability was defined as the amount of time after exposure to air for the silage temperature to reach 2°C above ambient temperature. The chopped forage was used in a 2 × 2 × 2 factorial arrangement of treatments: normal and moderately high DM contents, LB at 0 (untreated) or 4 × 10⁵ cfu/g of fresh forage, and LP at 0 or 1 × 10⁵ cfu/g. After 240 d of ensiling, corn silage harvested at the moderately high DM had higher pH, higher concentrations of ethanol, and more yeasts compared with the silage ensiled at the normal DM content. Inoculation with LB did not affect the concentration of lactic acid in silages with a moderately high DM, but decreased the concentration of lactic acid in the silage with normal DM. Higher concentrations of acetic acid were found in the silage treated with LB compared with those not treated with this organism. Inoculation with LP increased the concentration of lactic acid only in the silage with the normal DM content. The concentration of acetic acid was lower in silage treated with LP with a moderately high DM content, but greater in the silage treated with LP with the normal DM content when compared with silages without this inoculant. Appreciable amounts of 1,2-propanediol (average 1.65%, DM basis) were found in all silages treated with LB regardless of the DM content. The addition of L. buchneri increased the concentration of NH₃-N in silages but the addition of L. plantarum decreased it. Aerobic stability was improved in all silages treated with LB, with greater aerobic stability occurring in the silage with moderately high DM compared with silage with normal DM content. Inoculation with LP had no effect on aerobic stability. There were no interactions between L. buchneri and L. plantarum for most fermentation products or aerobic stability of the silages. This study showed that inoculating whole-plant corn with L. buchneri 40788 or L. plantarum MTD-1 has different beneficial effects on the resulting silage. There appear to be no major interactions between these organisms when added together to forage. Thus, there is potential to add both organisms simultaneously to improve the fermentation and aerobic stability of corn silage.     

Screening of a natural biodiversity of lactic and propionic acid bacteria for folate and vitamin B12 production in supplemented whey permeate

Lactic acid bacteria (LAB) and propionic acid bacteria (PAB) are known for the production of several important nutraceuticals. We screened 151 LAB and 100 PAB of different origins (fermented foods and feeds) for extracellular folate and intracellular vitamin B12 production in supplemented whey permeate using a standardized microbiological assay (folate) and HPLC (vitamin B12). Five LAB strains belonging to the species Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus brevis and Lactobacillus fermentum exhibited high extracellular folate productions, with a maximum yield of 397 ± 60 ng mL^?1 for L. plantarum SM39. The highest vitamin B12 production was measured for Propionibacterium freudenreichii DF15 with 2.5 μg mL^?1. Screening a large biodiversity of LAB and PAB led to a representative image of the distribution of folate and vitamin B12 production by these genera and enabled the identification of high natural folate and vitamin B12 producing strains with high potential for applications in fermented foods.     

Probiotic lactic acid bacteria for the production of multifunctional fresh-cut cantaloupe

Minimally processed fruits are an ideal alternative to dairy products to deliver probiotic microorganisms. At the same time, several innovative employments of lactic acid bacteria (LAB) have been proposed in the food industry, including bio-fortification with nutritional compounds and bio-protection against foodborne pathogenic bacteria. In this study, probiotic riboflavin over-producing Lactobacillus plantarum B2 and Lactobacillus fermentum PBCC11.5 were inoculated on fresh-cut cantaloupe by immersion in a dipping solution. The viability of probiotic microorganisms and the main physico-chemical parameters of melon pieces, including the riboflavin content, were monitored for 11 days of storage under refrigerated conditions. Finally, both probiotics were tested for their antagonistic effect against different concentrations of an isolate of Listeria monocytogenes from fruit origin. Overall, high viability of both probiotics species was found at the end of the shelf life. The main technological and nutritional parameters of the fruits were unaffected by probiotic-enrichment, except some sensorial attributes when melons were inoculated with L. plantarum B2. The riboflavin content increased about two-fold in probiotic cantaloupe. Moreover, L. plantarum B2 and L. fermentum PBCC11.5 showed a good ability to reduce the level of L. monocytogenes on artificially contaminated melons. In conclusion, the results of this work encourage further implementation of new foods with multifunctional properties.     

Stability of microencapsulated lactic acid bacteria under acidic and bile juice conditions

The probiotic strains Lactobacillus brevis CCMA1284 and Lactobacillus plantarum CCMA0359 were microencapsulated by spray drying using different matrices – whey powder (W), whey powder with inulin (WI) and whey powder with maltodextrin (WM). Viability of the microencapsulated strains in acid and bile juices and during 90 days of storage (seven and 25 °C) was evaluated. The two strains exhibited high encapsulation efficiency (> 86%) by spray drying. The different matrices maintained L. plantarum viability above six log CFU g⁻¹ at 7 °C for 90 days, whereas similar results for L. brevis were observed only for W. The use of inulin as matrix of encapsulation did not enhance bacterial viability in the evaluated conditions. In general, the use of W and WM as matrices was effective for L. plantarum viability. However, only W was effective for L. brevis in the evaluated conditions. The spray drying technique was successfully adopted for the encapsulation of L. plantarum CCMA0359 and L. brevis CCMA1284 strains.     

Evaluating the individual effects of temperature and salt on table olive related microorganisms

Statistical modelling techniques were used in the present study to assess the individual effects of temperature and NaCl concentration on the growth of 10 lactic acid bacteria and 6 yeast strains mostly isolated from different forms of table olive processing and belonging to the species Lactobacillus pentosus, Lactobacillus plantarum, Saccharomyces cerevisiae, Wickerhamomyces anomalus and Candida boidinii. The mathematical models obtained in synthetic laboratory media show that yeasts, except for C. boidinii, were more resistant to a high salt concentration than lactic acid bacteria, with an MIC value ranging from 163.5 (S. cerevisiae) to 166.9 g/L (W. anomalus); while for L. pentosus and L. plantarum this parameter ranged from 110.6 to 117.6 g/L, respectively. With regards to temperature, lactic acid bacteria showed a slight trend towards supporting higher temperature values than yeasts, with the exception of S. cerevisiae. The maximum temperatures for growth of L. pentosus and L. plantarum were 41.9 and 43.0 °C, respectively; while for W. anomalus and C. boidinii they were 38.2 and 36.5 °C. The optimum temperatures for growth were also higher for L. pentosus and L. plantarum (35.5 and 32.9 °C), compared to W. anomalus and C. boidinii (29.3 and 26.9 °C, respectively). Additional experiments carried out in natural olive brines confirmed previous results, showing that high NaCl concentrations clearly favoured yeast growth and that at high temperatures LAB slightly overcame yeasts. Results obtained in this paper could be useful for industry for a better control of both table olive fermentation and packaging.     

The role of plNC8HK-plnD genes in bacteriocin production in Lactobacillus plantarum KLDS1.0391

The function of plNC8HK gene and plnD gene on the bacteriocin production of Lactobacillus plantarum KLDS1.0391 was studied. The results of bioinformatics analysis showed that PlNC8HK protein was a histidine protein kinase and a cytoplasmic membrane protein with six transmembrane helices. PlnD protein was a response regulator of the LytR/AlgR family. Quantitative real-time PCR revealed that plNC8HK and plnD genes of L. plantarum KLDS1.0391 were up-regulated significantly (P < 0.01) when L. plantarum KLDS1.0391 co-cultured with Lactobacillus helveticus KLDS1.9207. The plNC8HK-plnD mutant was also constructed. The change of antibacterial activity, AI-2 activity and cell number of plNC8HK-plnD mutant in co-culture and mono-culture demonstrated that plNC8HK and plnD genes were essential for bacteriocin production in L. plantarum KLDS1.0391, and the increase of bacteriocin production correlated closely with plNC8HK and plnD genes in co-culture. These results are beneficial to understand the role of two components system in the bacteriocin production of L. plantarum.     

Electrospinning as a novel strategy for the encapsulation of living probiotics in polyvinyl alcohol/silk fibroin

The probiotic Lactobacillus plantarum (L. plantarum) were encapsulated with polyvinyl alcohol (PVA) and polyvinyl alcohol/silk fibroin (PVA/SF) nanofibers by electrospinning, respectively. Actually, different concentrations of PVA and SF have significant influence on the morphology of nanofibers, the optimized condition is 6% (w/w) SF and 8% PVA mixed. The L. plantarum on the nanofibers were characterized by scanning electron microscopy (SEM). The different features of PVA/L. plantarum and PVA/SF/L. plantarum nanofibers were proved by thermogravimetric (TGA) and Fourier transform infrared spectroscopy (FTIR). Microbiological tests showed that PVA/SF/L. plantarum exhibited increased survival rates evidently, after being treated in artificial gastric juice at 37 °C for 2 h, and the optical density (OD) value in stable growth period was 2.75, compared with free L. plantarum. The results of this study suggest a novel encapsulation approach that protects probiotic cells during their exposure to adverse environmental and intestinal conditions.     

Technological properties of candidate probiotic Lactobacillus plantarum strains

The study of new probiotic strains for their technological relevance and use in dairy products is important for trade and industry. Eight Lactobacillus plantarum strains isolated from Bulgarian cheeses and selected for their potential probiotic properties were characterized. In vitro tests with the API ZYM system revealed high aminopeptidase and phosphatase activity, and weak lipolytic activity. The L. plantarum strains showed also a weak proteolytic activity and were characterized as slow variants on the base of their coagulation ability. They maintained high viability in fermented milk over extended shelf-times at refrigerated temperature and demonstrated a good adaptation to 6% NaCl. Among the preservatives, only calcium propionate did not affect the growth of L. plantarum. The highest concentrations used of potassium sorbate (0.5 and 1%) and nisaplin (0.02%) decreased the bacterial growth. One L. plantarum strain was tested as an adjunct to commercially available formula for cream cheese. This candidate probiotic culture withstood the technological processing and retained high number of 10⁷ cfu g^?1 at the end of the 3 months storage period at 4 °C.     

Effect of Lactobacillus plantarum on the survival of acid‐tolerant non‐O157 Shiga toxin‐producing E. coli (STEC) strains in fermented goat's milk

The ability of goat's milk fermented with a Lactobacillus plantarum strain B411, and in combination with commercial starter culture, to inhibit acid‐adapted (AA) and non‐acid‐adapted (NAA) environmental non‐O157 STEC strains was investigated. Acid‐adapted and NAA non‐O157 STEC strains were not inhibited in the L. plantarum‐fermented goat's milk, while the goat's milk fermented with the combination of L. plantarum and starter culture inhibited AA more than NAA non‐O157 STEC strains. Environmental acid‐tolerant non‐O157 STEC strains were not inhibited by L. plantarum, starter culture or combination of starter culture with L. plantarum unless they were subjected to prior acid adaptation such as backslopping.     

Induction of bacteriocin production by coculture is widespread among plantaricin-producing Lactobacillus plantarum strains with different regulatory operons

We describe the bacteriocin-production phenotype in a group of eight singular bacteriocinogenic Lactobacillus plantarum strains with three distinct genotypes regarding the plantaricin locus. Genotyping of these strains revealed the existence of two different plantaricin-production regulatory operons, plNC8-plNC8HK-plnD or plnABCD, involving three-component systems controlled each of them by a specific autoinducer peptide (AIP), i.e. PLNC8IF or PlnA. While all of the strains produced antimicrobial activity when growing on solid medium, most of them halted this production when cultured in broth, thus reflecting the functionality of regulatory mechanisms. Antimicrobial activity in broth cultures was re-established or enhanced when the specific AIP was added to the culture or by coculturing with specific bacterial strains. The latter trait appeared to be widespread in bacteriocinogenic L. plantarum strains independently of the regulatory system used to regulate bacteriocin production or the specific bacteriocins produced. The induction spectrum through coculture, i.e. the pattern of bacterial strains able to induce bacteriocin production, was characteristic of each individual L. plantarum strain. Also, the ability of some bacteria to induce bacteriocin production in L. plantarum by coculture appeared to be strain specific. The fact that induction of bacteriocin production by coculturing appeared to be a common feature in L. plantarum can be exploited accordingly to enhance the viability of this species in food and feed fermentations, as well as to contribute to probiotic functionality when colonising the gastrointestinal tract.     

Effect of Lactobacillus plantarum LS5 on oxidative stability and lipid modifications of Doogh

The oxidative stability and lipid modifications of Doogh prepared with Lactobacillus plantarum LS5 and control Doogh were compared during storage for 22 days. In vitro scavenging activity against 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radicals showed that L. plantarum LS5 had radical scavenging activities (49.6%). Peroxide value, conjugated diene value and anisidine value measurements in Doogh lipid samples in combination with Fourier transform infrared spectroscopy demonstrated that Doogh prepared with L. plantarum LS5 was more stable than the control against formation of primary and secondary oxidation products. Furthermore, higher concentrations of short‐chain fatty acids (butyric and caproic) and unsaturated fatty acids were found in Doogh treated with L. plantarum LS5. Changes in the thermograms of all samples were also observed. Results of differential scanning calorimetry indicated that melting points of lipids from treated Doogh were lower than for the control. It was concluded that L. plantarum LS5 could be used as a natural preservative in functional dairy products and could beneficially affect the consumer by providing dietary sources of antioxidants.     

Synergistic effects of combinatorial Lactiplantibacillus plantarum fermentation and vegetable oils supplementation on the lycopene level,antioxidant capacities and flavor volatiles of tomato pulp

The objective of this study was to investigate the effects of Lactiplantibacillus plantarum (L. plantarum) fermentation and three types of vegetable oils (corn oil, peanut oil, and olive oil) supplementations on the physicochemical properties, bioactive components, and flavor volatiles of tomato pulp. Tomato pulp supplemented with oils was excellent food matrices for L. plantarum growth, and the colony counts remained above 8.3 log CFU/mL at the end of fermentation. The contents of total phenol, carotenoids and lycopene were dramatically increased after fermentation, and oils supplementation exhibited a synergistic promotion effect, especially for the combination of L. plantarum fermentation and 3% olive oil supplementation exhibiting the highest lycopene level (30 mg/mL), the strongest DPPH radical scavenging activity (84.24%) and FRAP (16.45 mmol Trolox/L). Furthermore, synergistic L. plantarum fermentation and oils supplementation decreased aldehydes content, and increased alcohols, esters, and ketones formation, meaning the improved flavor characteristics of fermented tomato pulp.Industrial relevanceIn this study, a functional beverage of tomato pulp was prepared by the combination of L. plantarum fermentation and vegetable oils supplementation. Colony counts, lycopene level, antioxidant capacities, and flavor characteristics were dramatically improved at the end of fermentation. This study provides an innovative technology to improve the release of lycopene from plant tissue and provide a functional beverage of tomato pulp with high health benefits.     

Quantification of Mold in Hay by near Infrared Reflectance Spectroscopy

Near infrared reflectance spectroscopy was used to quantify mold by spectrally predicting chitin, a fungal cell wall polymer of glucosamine. Chitin data and near infrared reflectance spectra were collected from moldy alfalfa (Medicago sativa L.) hay samples. Chitin concentrations ranged from 75 to 710 μg/g DM and were similar to concentrations in other contaminated products. Second derivative math transformations were made on the spectra, and a calibration equation was developed by regressing transformed spectra against chemical data. The coefficients of determination for calibration and validation were .90 and .82, respectively. Standard errors of calibration and validation were 44 and 65 μg/g DM, respectively. The calibration equation utilized four terms, represented at wavelengths 1630, 2114, 2246,and 2356 nm. The spectra of commercial glucosamine were plotted, and reflectance peaks occurred at 2114 and 2356 nm. The validated equation was used to predict mold (chitin) in bales that had been visually estimated for mold with a relative mold index. Relative mold index was regressed against chitin and was correlated to chitin (R=.86); residual error was small when samples were extremely moldy or clean. We concluded that near infrared reflectance spectroscopy can accurately quantify mold in alfalfa hay.     

Effects of branched-chain amino acids and Lactobacillus plantarum CGMCC18217 on volatiles formation and textural properties of dry-cured fermented sausage

This study aimed to evaluate the effect of branched-chain amino acids (BCAAs, leucine, isoleucine and valine) combined with Lactobacillus plantarum CGMCC18217 (L. plantarum) on the flavours and quality of fermented sausages. The parameters included pH, water activity, colour, texture, BCAAs metabolites and flavour compounds of fermented sausages in eight different groups (sausages with L. plantarum and individual BCAAs, that is L + Leu, L + Ile and L + Val groups; sausages with individual BCAAs, that is the Leu, Ile and Val groups; sausages only with L. plantarum assigned as the L group; and sausages with no L. plantarum and BCAAs assigned as the CK group). The results showed that the addition of BCAAs and L. plantarum significantly increased the hardness, cohesiveness and springiness of sausages. A total of sixty-nine flavour compounds were identified in fermented sausages. The content of methyl-branched alcohols, aldehydes, acids in the L. plantarum and BCAAs group significantly increased compared with the other groups (P < 0.05). Therefore, our data suggest the addition of L. plantarum and BCAAs potentially improved the texture of fermented sausages and formation of volatile flavours.