Effect of antioxidants in combination of VCO nanoemulsion on gel properties and storage stability of refrigerated sardine surimi gel

Impacts of β-glucan–virgin coconut oil (VCO) nanoemulsion containing epigallocatechin gallate (EGCG) and α-tocopherol at levels of 0–3.0 g kg⁻¹ on properties and storage stability of surimi gel were investigated. Augmented breaking force, deformation and fracture constant were obtained in gels containing 2.0 g kg⁻¹ EGCG or 1.0 g kg⁻¹ α-tocopherol (P < 0.05). Expressible moisture content increased as EGCG levels were more than 2.0 g kg⁻¹. Smoother microstructure was observed in gels containing 2.0 g kg⁻¹ EGCG. Whiter gels were obtained when β-glucan–VCO nanoemulsion was incorporated. No change in protein pattern of gels was observed regardless of antioxidant incorporation. Viscoelastic moduli decreased as β-glucan–VCO nanoemulsion was added; however, incorporation of 2.0 g kg⁻¹ EGCG or 1.0 g kg⁻¹ α-tocopherol lowered the decrease in G'. β-glucan–VCO nanoemulsion containing gels had higher likeness scores than the control (P < 0.05). Gels containing EGCG and α-tocopherol at selected levels had the improved oxidative stability and lowered microbial loads.     

Quality and hygiene of beef burgers in relation to the addition of sodium ascorbate,sodium citrate and sodium acetate

We evaluated the effects of two additive mixtures (sodium ascorbate 1 g kg^?1, sodium citrate 1 g kg^?1 and sodium acetate 1.75 or 2.5 g kg^?1) on the microbiological and physical–chemical characteristics of non‐prepacked beef burgers stored in air at 4 °C or 12 °C for 96 h. Total microbial count reached 7 Log CFU g^?1 48 h later in treated samples at 4 °C. The mixture containing the higher acetate concentration led to a smaller increase in Gram‐negatives, in particular Pseudomonas (2 Log of difference towards control samples at 96 h); at 12 °C, a 1.7 Log difference in Enterobacteriaceae was also shown. Total viable basic nitrogen was significantly lower in the treated samples at 12 °C. The addition resulted in pH stabilisation and lower cooking loss and positively influenced the a* index of burgers at 4 °C. Clearly, the use of these mixtures should not be a substitute of good hygienic practices and optimal storage conditions.     

Changes of microbial diversity and volatile compounds in edible and deteriorated Qingke barley fresh noodles stored at 25 °C

Microbial diversity and volatile compounds in Qingke barley fresh noodles (QBFN) with different storage time at 25 ± 1 °C were investigated. The results showed that Pseudomonas, Pantoea, Erwinia and Alternaria, Pyrenophora, Penicillium were the dominant microorganisms in edible QBFN (stored for 0 and 12 h), while Pantoea, Erwinia, Bacillus and Penicillium, Aspergillus were the dominant spoilage microorganisms in deteriorated QBFN (stored for 18 h). The edible QBFN have high concentration of aldehydes (61.27 μg kg⁻¹), furan and pyrazines (60.87 μg kg⁻¹), alcohols (49.74 μg kg⁻¹) and ketones (29.74 μg kg⁻¹) that give basic flavours to the QBFN. As storage time increased, the concentrations of above volatile compounds decreased, and new esters and sulphuric compounds which gave unpleasant odours to the QBFN appeared. Multivariate data analysis methods showed that 2-pentyl-furan, hexanal, 5-Ethylcyclopent-1-enecarboxaldehy, cyclohexanol and methyl allyl sulphide, ethyl isovalerate were the main volatile compounds that make a difference in flavour between the edible and deteriorated QBFN.     

Effect of debittering and solid-state fermentation processes on the nutritional content of lupine (Lupinus mutabilis Sweet)

There is a growing interest in vegetable-based sources of proteins. Despite its high nutrient content, lupine has been rarely exploited as a protein source due to the presence of high levels of non-nutritive compounds such as alkaloids, which impart a bitter taste. Here, we evaluated the effect of debittering and solid-state fermentation on the nutritional contents of three lupine varieties (Lupinus mutabilis Sweet). These processes induced significant changes (P < 0.05) in the nutritional composition of the three lupine varieties (INIAP-450, INIAP-451 and Criollo) and increased the protein levels to 644.55 g kg⁻¹ (Criollo variety) and the levels of several constituent amino acids such as valine (54.62 g kg⁻¹), methionine (42.47 g kg⁻¹), isoleucine (59.27 g kg⁻¹) and leucine (76.32 g kg⁻¹). The ether extract of INIAP-450 showed increased levels (up to 244.03 g kg⁻¹); especially, monounsaturated fatty acids (559.78 g kg⁻¹) and polyunsaturated fatty acids (293.17 g kg⁻¹) were observed. The omega-6/omega-3 ratio in the debittered grain oil reached the minimum requirement established for good-quality oils (5/1). However, the levels of other components decreased, showing levels up to 13.04 g kg⁻¹ (total starch) in the Criollo variety, 22.62 g kg⁻¹ (resistant starch) in INIAP-450, 6.53 g kg⁻¹ (potassium) in INIAP-451, 46 g kg⁻¹ (iron) in INIAP-451 and 29.75 g kg⁻¹ (zinc) in INIAP-450.     

Consumers' acceptance and quality stability of olive oil flavoured with essential oils of different oregano species

The objective of this study was to evaluate chemical and physical stability and consumers' acceptance of olive oil flavoured with oregano essential oils (EOs; Compacto, Cordobes, Criollo and Mendocino). Samples of olive oil were added with 0.05% EO and stored in dark (D) and light (L) conditions for 126 days. Samples with oregano EO had lower lipid oxidation indicator values [K232, K269, peroxide value (PV) and anisidine value], especially in darkness. Olive oil with Cordobes EO in D had the lowest PV (18.71 meqO₂ kg^?1). Using prediction equations, 20 meqO₂ kg^?1 PV in olive oil should be reached in 34 days in L control sample and in 126 days in the Cordobes EO sample in darkness. Samples with Cordobes and Criollo EOs in darkness had the highest chlorophyll content after 126 days (2.91 and 2.88 mg kg^?1, respectively). Sensory analysis showed that oregano EO addition in olive oil was detected by panellists in discriminative test and affected consumer acceptance.     

Effect of bioaugmentation on biochemical characterisation and microbial communities in Daqu using Bacillus,Saccharomycopsis and Absidia

Daqu, a saccharifying and fermenting agent for the production of Chinese vinegar and liquor, is manufactured through a spontaneous solid-state fermentation process (SSF). To investigate the influence of bioaugmentation with native microorganisms on Daqu SSF process, physicochemical properties, microbial biomass, volatile compounds and microbial communities were analysed in laboratory-scale Daqu. The results showed that the amylase activity of Daqu enhanced 6.35% ± 0.74% by inoculating Bacillus amyloliquefaciens, Saccharomycopsis fibuligera and Absidia corymbifera. Obviously higher microbial richness was found in the Daqu with bioaugmentation, although the microbial community structure remained relatively stable. Moreover, a total of twenty-two volatile compounds were detected in the mature Daqu. Slightly increase in the content of alcohols was found in the enhanced group by fungal inoculation, including ethanol (46.58 ± 1.36 mg kg⁻¹), isobutanol (0.19 ± 0.04 mg kg⁻¹) and isoamyl alcohol (1.55 ± 0.13 mg kg⁻¹). This study demonstrated that bioaugmentation had a positive effect on the amylase activity, main volatile compounds and microbial community richness.     

Combined washing effect of noni extract and oregano essential oil on the decontamination of Listeria monocytogenes on romaine lettuce

Combined washing effect of noni extract (NE) and oregano essential oil (OE) on the decontamination of Listeria monocytogenes on romaine lettuce was examined. The fractional inhibitory concentration index (FICI) between NE and three different essential oils (cinnamon leaf, thyme and OE) was determined. Fractional inhibitory concentration index results indicated that OE only had an additive effect (FICI = 1). Noni extract/oregano essential oil combined washing resulted in the greatest reduction in viable cell numbers (3.42 log CFU g⁻¹) relative to non-washed samples. Furthermore, the combined washing was more effective than sodium hypochlorite washing in terms of reducing the microbial load (>1.44-log reduction). Washing treatment did not change the surface colour or total phenolic content in lettuce samples. These results suggest that NE/OE combined washing is applicable as a novel decontamination treatment to ensure the microbial safety of romaine lettuce without changing the quality.     

Composition of oregano essential oil (Origanum vulgare) as affected by drying method

The influence of the drying method on volatile compounds of Origanum vulgare was evaluated. The drying methods tested were convective (CD) at 60 °C and vacuum-microwave (VMD), as well as a combination of convective pre-drying and VM finish-drying (CPD–VMFD). The volatile compounds of fresh and dried oregano were extracted by steam-hydrodistillation and analyzed by GC–MS. Oregano drying kinetics was described by a simple exponential model for CD and CPD–VMFD, while VMD kinetics consisted of two periods: linear until a critical point and exponential beyond that point. Thirty-four compounds were tentatively identified, with carvacrol, thymol, and γ-terpinene, being the major components. The total volatiles concentration of fresh oregano (33.0 g kg⁻¹) decreased significantly during drying, independently of the method used (CD: 10.2 g kg⁻¹, CPD–VMFD: 13.1 g kg⁻¹, and VMD: 27.9 g kg⁻¹). The final conclusion was that VM dehydrated Polish oregano was of better aromatic quality than that dried using hot air.     

Effect of autochthonous starter cultures on the volatile flavour compounds of Chinese traditional fermented fish (Suan yu)

Effect of autochthonous starter cultures on the volatile flavour compounds of Chinese traditional fermented fish was studied. Lactobacillus plantarum 120, Staphylococcus xylosus 135 and Saccharomyces cerevisiae 31, isolated from Suan yu, were selected as starter cultures. Volatiles were extracted by headspace solid‐phase microextraction (SPME) and analysed by gas chromatography–mass spectrometry technology (GC‐MS). Esters and alcohols were the main components of volatiles, accounting for over 50 percentage points in all samples. The highest content of esters (3034.54 μg kg^?1) was observed in S1 inoculated with L. plantarum 120, while the highest content of alcohols (2164.53 μg kg^?1) and ketones (379.98 μg kg^?1) was detected in S3 inoculated with S. cerevisiae 31. The content of acids and aldehydes was lower in inoculated samples. Principal component analysis revealed that the volatile composition was primarily influenced by the nature of the starter cultures. L. plantarum 120 and S. xylosus 135 could accelerate fermentation.     

Partial replacement of meat by sugar cane fibre: cooking characteristics,sensory properties of beef burgers and in vitro fermentation of sugar cane fibre

In this study, sugar cane fibre (SCF) partially replaced meat in beef burger formulations. The effects of SCF on cook yield, dimensional changes, sensory characteristics of beef burgers and in vitro gut fermentation characteristics were evaluated. Replacing beef with 1 to 5% SCF in burgers significantly increased cook yields from 13.8 ± 0.3 to 59.1 ± 0.3% due to its high water-binding capacity of 5.89 ± 0.08 g g⁻¹ and oil-binding capacity of 4.68 ± 0.03 g g⁻¹. The inclusion of SCF improved cooking properties whilst improving sensory characteristics. Burgers with 1% SCF had the highest overall acceptability. SCF was steadily fermented with a porcine faecal inoculum for up to 72 h, producing short-chain fatty acids. The characteristics of high water/oil binding and fermentability suggest that SCF has the potential to provide a range of dietary fibre benefits, and therefore deserves further study.     

Determination of menaquinone production by Lactococcus spp. and propionibacteria in cheese

Two genera of lactic acid bacteria are principally known to produce menaquinones in cheese: Lactococcus spp. in semi-hard cheese such as Vacherin Fribourgeois and Raclette, and propionibacteria in Swiss-type cheese such as Emmental. Menaquinone (MK) content of several cheese loaves was analysed to determine the impact of sampling site, ripening time and cultures used during cheese making. With Lactococcus spp., in Vacherin and in Raclette, the principal menaquinone was MK-9 (median = 149 μg kg⁻¹ and median = 167 μg kg⁻¹) followed by MK-8 (median = 70 μg kg⁻¹ and median = 66 μg kg⁻¹). In Emmental cheese, the principal menaquinone was MK-4 (median = 48 μg kg⁻¹) in young cheese and MK-9(4H) (median = 468 μg kg⁻¹) in cheese older than 90 days. The only difference in sampling site was found in Raclette for MK-9. In Vacherin, MK-8, MK-9 and total contents of menaquinones were significantly different according to the strain of Lactococcus lactis ssp. cremoris used.     

The Effects of Natural Extracts on the Quality Changes of Frozen Chub Mackerel (Scomber japonicus) Burgers

The effects of the use of natural antioxidants on the quality of frozen chub mackerel (Scomber japonicus) burgers stored at ?18 °C were investigated in terms of sensory, biochemical (thiobarbituric acid reactive substances-TBARS, total volatile basic nitrogen, peroxide value and free fatty acids) and microbiological analyses (total viable count—TVC, total psychrotrophic count—TPC). Oregano, green tea, sage and laurel extracts were obtained by using steam distillation method. After that, thawed fish were headed, gutted and filleted. Fillets were then minced and divided into nine groups. These were the control without plant extract, O1 with 0.3% oregano extract, O2 with 0.6% oregano extract, G1 with 0.3% green tea extract, G2 with 0.6% green tea extract, S1 with 0.3% sage extract, S2 with 0.6% sage extract, L1 with 0.3% laurel extract and L2 with 0.6% laurel extract. Plant extracts together with burger ingredients were added to each group. All groups were stored at ?18 °C for 9 months. According to the results of sensory analyses, the control at 7 months of storage, oregano and green tea at 9 months of storage, sage and laurel groups at 8 months of storage were rejected by panellists and considered as unaccepptable. Natural extracts were effective in controlling biochemical indices. TVC content of fish burgers did not exceed the limit during storage period for all groups (<6 log CFU/g). TPC slightly decreased with storage time. Additions of oregano, green tea and laurel extracts except sage extract reduced (P?<?0.05) lipid oxidation in fish burger and have the potential to be incorporated into fish burgers.     

Development of a HPLC method combined with ultraviolet/diode array detection for determination of monosodium glutamate in various food samples

An effective, simple and rapid analytical method using HPLC was developed for the analysis of monosodium glutamate (MSG) in various food samples obtained from local market in Turkey. The determination of MSG was performed by its derivatisation with o-phthaldialdehyde (OPA). A high-performance liquid chromatography-ultraviolet/diode array detection method was performed by using C₁₈ (150 mm × 4.6 mm, 2.7 μm) column with the mobile phase consisting of 10 mm phosphate buffer solution (pH = 5.90) and methanol (75:25, v/v). The applied method was optimised and the validated. The method was linear from 1 to 50 μg mL⁻¹ of MSG. The correlation coefficient value of the developed method was obtained as R² = 0.9999. The limit of detection and limit of quantification limits were 0.015 and 0.050 μg mL⁻¹, respectively. MSG contents of the food samples range from 0.09 g kg⁻¹ to 120.80 g kg⁻¹. The validated method was successfully applied for the analysis of MSG in several food samples.     

Practical use of β-carotene-loaded nanoemulsion as a functional colorant in sausages made from goat meat surimi-like material

The potential applicability of β-carotene-loaded nanoemulsion (CNE) as a natural colorant in non-smoked sausage made from goat meat surimi-like material (GMS) was elucidated. The effect of CNE content (0–30 g 100 g⁻¹) on the physicochemical characteristic, oxidative stability and β-carotene remaining during cold storage (4 °C) was determined. The higher the CNE, the greater the a*, b* and redness index with the lower L*, and colour likeness score. CNE content had a little impact on the moisture content, a_w and pH of sausages over storage period. However, the expressible drip, breaking force and deformation were largely influenced by the CNE content. All CNE-containing sausages displayed a superior oxidative stability to control. Among CNE-incorporated samples, the lowest lipid oxidation and β-carotene degradation were noticeable in the sausage with 10 g 100 g⁻¹ CNE. Thus, the CNE at 10 g 100 g⁻¹ was a promising functional colorant for emulsion sausage made from GMS.     

Effect of chitooligosaccharide from squid pen on gel properties of sardine surimi gel and its stability during refrigerated storage

Effect of chitooligosaccharide from squid pen prepared using lipase (COS-L) at various concentrations (0–30 g kg⁻¹) on gel properties of sardine surimi gel was investigated. Breaking force (BF) and deformation (DF) of gel were increased, when COS-L level was increased up to 10 g kg⁻¹ (P < 0.05). Water holding capacity and whiteness of gel were improved with the addition of COS-L than those of control. Gel added with 10 g kg⁻¹ COS-L had denser network with higher likeness score for all sensory attributes, compared to control. When gel incorporated with 10 g kg⁻¹ COS-L was stored at 4 °C, BF, DF and whiteness were maintained during 10 days of storage. Textural properties of surimi gel added with COS-L were higher than those of control throughout storage. Thus, incorporation of 10 g kg⁻¹ COS-L could improve gel properties of sardine surimi gel and retarded the deterioration of gel properties during refrigerated storage.     

Use of nanoliposome loaded with chitosan-epigallocatechin gallate conjugate for shelf-life extension of refrigerated Asian sea bass (Lates calcarifer) slices

Treatments of chitosan-epigallocatechin gallate (CE) conjugate nanoliposome (CELP) and unencapsulated CE conjugate (UNCE) at different concentrations (0.025  and 0.05 g 100 g⁻¹) on quality and shelf-life of Asian sea bass slices (ASB-S) kept at 4 °C were studied. Total viable count of ASB-S treated with 0.05 g 100 g⁻¹ CELP (SB-CELP-0.05) was less than permissible limit (6 log CFUg⁻¹ sample) within 15 days. Moreover, SB-CELP-0.05 sample had the lowest pathogenic and spoilage bacterial count than remaining samples during the storage (P < 0.05). Lower thiobarbituric acid reactive substances and peroxide values were obtained for SB-CELP-0.05 sample than those treated with 0.05 g 100 g⁻¹ UNCE (SB-UNCE-0.05) at the end of storage (P < 0.05). The result was also advocated by higher polyunsaturated fatty acid content of SB-CELP-0.05 than SB-UNCE-0.05 (P < 0.05). Therefore, CELP efficiently extended ASB-S shelf-life with high consumer acceptability at 4 °C for minimum 12 days, whereas control had the shelf-life less than 6 days.     

Selenium supplementation of diets of dairy cows to produce Se-enriched cheese

Selenium (Se) deficiency in people and animals is a nutritional problem in many regions of the world. Ten mid-lactation Estonian Red dairy cows were supplemented for 64 days with inorganic Se [0.39 mg kg⁻¹ in total mixed ration (TMR)] followed by a 57-day period of supplementation with organic and inorganic Se (0.44 mg kg⁻¹ in TMR), according to EU directives on maximum allowed amounts. Feeding organic Se increased Se content in blood (from 186.5 to 287.9 μg kg⁻¹), milk (from 17.1 to 51.8 μg kg⁻¹) and Edam-type cheese made there from (from 146 to 361 μg kg⁻¹). Se content in milk after supplementation was high enough to produce a cheese enabling the nutrition claim “high in Se” and related health claims. The concentration of the main primary oxidation products of linoleic acid (oxylipins) was low and leukotoxin diols were found in trace amounts; the oxidative stability of cheeses was high.     

Evaluation of antibacterial protein with antioxidant activity from Rahnella aquatilis L103 and its effect on beef during refrigerated storage

A strain, Rahnella aquatilis L103, which was isolated from the soil around the roots of mushrooms, produced antibacterial protein though fermentation. This protein has broad antibacterial spectrum towards gram-positive and gram-negative bacteria. The protein has a significant antioxidant capacity on scavenging ABTS^+· (82.5%, 120 μg mL⁻¹), DPPH^· (64.1%, 600 μg mL⁻¹) and OH^· (60.1%, 750 μg mL⁻¹) as well. The protein was considered to be safe within concentration of 150 μg mL⁻¹ as shown by MTT results and was applied to beef refrigerated preservation. The treatment group presented lower total viable counts (TVC), total volatile basic nitrogen (TVB-N), 2-thiobarbituric acid (TBA), meanwhile, higher sensory score and longer shelf life (2 days) compared with the control group (P < 0.05). The results indicated that the protein under safe concentration was beneficial to beef preservation.     

Physical,antimicrobial and antibiofilm properties of Zataria multiflora Boiss essential oil nanoemulsion

It was evaluated physical, antibacterial and antibiofilm properties of Zataria multiflora Boiss essential oil (ZEO) and its nanoemulsion. Long‐term stability of nanoemulsion prepared by emulsion phase inversion was satisfying based on low narrow size distribution (polydispersity index ?0.2) and low droplet size (200 nm) over 21 days of storage. Nanoemulsion showed lower minimum inhibitory concentration (MIC) on Listeria monocytogenes (2500 µg mL^?1) than Salmonella Typhimurium (5000 µg mL^?1). Killing kinetics study revealed that nanoemulsion was more effective in inhibiting the growth of bacteria in milk than culture media. Both bacteriostatic and bactericidal effects were observed depending on the type of bacteria, nanoemulsion concentration and the time of exposure. Nanoemulsion at 4×MIC concentration reduced 64% and 75% of one‐day‐old biofilm of L. monocytogenes and S. Typhimurium, respectively. In conclusion, nanoemulsion revealed antimicrobial activity, but converting the ZEO to nanoemulsion did not improve its antibacterial activity; however, antibiofilm properties were enhanced.     

Quality changes of farmed cobia steaks held in cold stores (−18 °C)

Cobia (Rachycentron canadum) steaks held in cold store (?18 °C) were analysed aseptically in triplicates for the sensory, total aerobic bacterial count, proximate composition, pH, thiobarbituric acid‐reactive substance (TBA‐RS), formaldehyde, total volatile base nitrogen (TVB‐N), trimethyl amine‐nitrogen (TMA‐N), salt soluble nitrogen (SSN), nonprotein nitrogen (NPN), sodium dodecyl sulphate‐poly acrylamide gel electrophoresis (SDS‐PAGE) pattern. Steaks were sensorially acceptable up to 5 months of storage and the total bacterial counts did not exceed 6 log CFU counts. There were no significant changes in the pH values. TBA‐RS values increased significantly (P < 0.05) and reached 7.34 mg of malonaldehyde kg^?1 fat at the end. Formaldehyde content remained constant upto 4th month and later increased to 2.06 μg g^?1 (P < 0.05). TVB‐N and TMA‐N values did not exceed the acceptable limits. NPN contents showed no change, while SSN contents increased to 1.24% after 5 months. SDS‐PAGE pattern indicated no protein denaturation in the fish tissue. Results indicated that TBA‐RS value can only be considered as the valuable indicator in determining the quality of fish steaks held in cold stores.