Formation and dispersal of biofilms in dairy substrates

The formation and dispersion of biofilms in the dairy industry is a problem because it increases cross‐contamination, affecting the shelf life of the products and their safety. The objective of this study was to evaluate the influence of different dairy substrates (cows’ milk and whey protein) on the formation and dispersion of Enterococcus faecalis, Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus in two biofilm systems (mono‐species and multi‐species) on stainless steel at 25 °C. The dominant behaviour of E. faecalis occurred in most of the tests on mono‐species and multi‐species biofilms. A greater dispersion of biofilm cells was observed in skimmed milk.     

Effect of nisin‐producing Lactococcus lactis starter cultures on the inhibition of two pathogens in ripened cheeses

The effect of Lactococcus lactis nisin‐producing strains, isolated from Italian fermented foods, on the survival of two foodborne pathogens namely Listeria monocytogenes and Staphylococcus aureus was investigated in experimental cheese production. One of the three Lactobacillus lactis nisin innoculated as starters, Lactobacillus lactis 41FL1 lowered S. aureus count by 1.73 log colony‐forming units (cfu)/g within the first 3 days, reaching the highest reduction, 3.54 log cfu/g, by the end of ripening period of 60 days. There was no effect on L. monocytogenes. The application of L. lactis 41FL1 as bioprotective culture in controlling S. aureus shows considerable promise.     

Nutritional composition and sensory attributes of Alaskan flatfishes compared to plaice (Pleuronectes platessa)

Proximate composition, fatty acids profiles and other nutritional values were evaluated for fillets of Limanda aspera (yellowfin sole), Lepidopsetta bilineata (southern rock sole) and Lepidopsetta polyxystra (northern rock sole) and compared to North Sea plaice (Pleuronectes platessa). Additional information is given on the composition of fillets from arrowtooth flounder (Atheresthes stomias). Plaice (0.8% lipid) and Alaska soles (1.0–1.2% lipid) can be classified as lean species, resulting in low 0.3–0.5 g ∑EPA+DHA/100 g muscle, although the fatty acid profiles of the extracted lipids were characterised by high amount of n‐3 fatty acids (33.2–47.3%). Arrowtooth flounder belong to the medium‐fat species (4.3%). Taurine was the most prevalent free amino acid; mean values ranging between 221 mg100 g^?1 and 247 mg100 g^?1 wet weight. The selenium content varied between 130 and 310 μg kg^?1 ww. Sensory attributes of Southern and Northern rock sole were comparable to plaice.     

Detection and quantification of Escherichia coli and Pseudomonas aeruginosa in cow milk by near‐infrared spectroscopy

This work investigated the potential of NIR technology to be applied in the dairy industry for the detection of micro‐organisms. To this end, two types of cow milk samples were studied, one in which only bacterial biomass was considered and the other in which bacteria were cultured and grown in milk for 24 h. The study was carried out using two micro‐organisms Escherichia coli and Pseudomonas aeruginosa. Both types of samples with different counts of both micro‐organisms were analysed by a NIR analyser in the range 10 000–4000 cm^?1 based on transmittance measurements. Multivariate models indicated that a better discrimination between micro‐organisms was attained in those milk samples in which micro‐organisms have been grown.     

Characterisation of the technological behaviour of mixtures of mesophilic lactic acid bacteria isolated from traditional cheeses made of raw milk without added starters

In this work, the technological behaviour in milk of a set of Lactococcus lactis strains, alone or in combination with strains of Leuconostoc spp. and Lactobacillus spp. isolated from traditional, raw milk cheeses made without commercial starters, was investigated. Small, mixture‐specific differences during milk fermentation were recorded for growth, milk acidification and production of organic acids, volatile compounds, free amino acids and biogenic amines. Four combinations appropriate for use as dairy starters were tested in pilot‐scale cheese trials. Two mixtures produced cheeses of high flavour and taste quality; these could be confidently used as starter cultures.     

Inferring the role of microorganisms in water kefir fermentations

Water kefir is a slightly alcoholic, lactic and acetic beverage fermented by yeasts, lactic acid bacteria and acetic acid bacteria that are associated with the polysaccharide of the water kefir grains. In this study, the three main metabolic products of microorganisms were evaluated during a traditional 192‐h water kefir fermentation and also after inoculating the microorganisms in fresh medium or sterilised broth from different fermentation stages. The first process to occur was alcoholic fermentation, carried out in particular by Saccharomyces cerevisiae. After 24 h, lactic and acetic acid accumulation was generated by Lactobacillus hilgardii and Acetobacter tropicalis. By the end of fermentation, ethanol had been almost entirely consumed and oxidised to acetic acid, possibly by a dissimilatory route of Acetobacter species. An original hypothetical diagram is proposed for the carbon flux from sucrose, and the metabolic role of the main yeasts and bacteria is assigned for the distinct stages of water kefir fermentation.     

Detection of Salmonella spp., Yersinia enterocolitica,Listeria monocytogenes and Campylobacter spp. by real‐time multiplex PCR using amplicon DNA melting analysis and probe‐based assay

Syto9 and probe‐based multiplex real‐time PCR assays for simultaneous detection of a group of foodborne pathogens (named SYLC group), targeting Salmonella spp. (invA gene), Yersinia enterocolitica (ystA gene), Listeria monocytogenes (hly gene) and Campylobacter spp. (rrna gene), have been developed. The Syto9 assay generates amplicon DNA melting curve with four peaks of 86.5 ± 0.5, 84 ± 0.5, 81.5 ± 0.5 and 90.5 ± 0.5 °C corresponding Salmonella spp., Y. enterocolitica, L. monocytogenes and Campylobacter spp. targets, respectively. The sensitivities of the Syto9 and TaqMan assays in artificially inoculated chicken wing rinses were in a range of 3.2 × 10² to 3.1 × 10⁴ and 9.8 × 10² to 1.9 × 10⁴ colony‐forming units per millilitre, respectively, depending on the pathogen. All tested target strains (n = 100) were correctly detected by the both assays, whereas nontarget strains (n = 100) demonstrated no cross‐reactivity representing 100% specificity. The assays are suitable for application in qualitative and quantitative detection of SYLC group pathogens in food matrices.     

Neural network models for growth of Salmonella serotypes in ground chicken subjected to temperature abuse during cold storage for application in HACCP and risk assessment

Predictive microbiology models are valuable tools for helping to assess and manage the risk of illness from food contaminated with human pathogens, such as Salmonella. However, multiple versions of a model may be needed for different food safety applications, such as hazard analysis and critical control point (HACCP) programs and risk assessment. A neural network model for growth of Salmonella in ground chicken as a function of time (0 to 8 days) at 16 °C and serotype (n = 8) was developed. The proportion of residuals in an acceptable prediction zone (pAPZ) from ?1 log (fail‐safe) to 0.5 log (fail‐dangerous) was 0.948 for training data (n = 192) and 0.988 for testing data (n = 84). A pAPZ ≥0.7 indicated that the model provided predictions with acceptable bias and accuracy. Thus, the model was successfully validated. Different versions of the model were developed for application in HACCP and risk assessment.     

Evaluation of physico‐chemical properties,trace metal content and antioxidant activity of Indian honeys

In this study, effect of plant sources viz. Gossypium hirsutum, Coriander sativum, Murraya koenigii and Dalbergia sisso on twelve physico‐chemical properties, phenolic content, flavonoids content as well as on trace mineral (Fe, Cu, Ni, Mn, Cd and Pb) contents of honey were investigated and compared. All the physico‐chemical values were in the range of approved limits of European Commission Regulation and the source of honey had a significant (P < 0.05) effect on physico‐chemical properties, phenol content, flavonoid content and trace mineral content. The results of positive correlations between physico‐chemical properties (colour and antioxidant properties) and compositional components (phenols and flavonoids content) established that antioxidant properties were dependent on source of honey rather than on colour of honey. Pattern recognition methods such as principal component analysis and linear discriminate analysis were performed to classify honey on the basis of physico‐chemical properties, phenolic content, flavonoids content and trace metal content. The variables proline and lead exhibited higher discrimination power.     

Effect of thermosonication in a batch system on the survival of spore‐forming bacteria

Thermosonication may help reduce bacteria counts responsible for spoilage in dairy products. Vegetative cells and spores of Geobacillus stearothermophilus, Anoxybacillus flavithermus and Bacillus subtilis (spores only) were treated with either heat alone or thermosonication in a batch system from 0 to 120 s in tryptic soy broth and 2% fat milk at 72 and 73 °C. D‐values for vegetative cells were calculated and were reduced after thermosonication. Maximum reduction in vegetative cells after thermosonication was 1 log after 30–45 s and for spores was ≤0.2 log after 120 s, which may not influence dairy product quality in scale‐up systems.     

The effect of enzymatic hydrolysis on the biological properties of Oenothera biennis,Borago officinalis and Nigella sativa seedcake by‐products from oil pressing

The biological properties of ethanolic (50%, v/v) extracts from Oenothera biennis, Borago officinalis, Nigella sativa seedcake before and after enzymatic hydrolysis by alpha‐amylase (EC 3.2.1.1) from Aspergillus oryzae, beta‐glucosidase (EC 3.2.1.21) and beta‐glucanase (EC 3.2.1.6) from Aspergillus niger combinations in a ratio of 1:1:1 were investigated. Total phenolic, flavonoid and reducing sugar content for O. biennis extract after enzymatic hydrolysis was, respectively, 0.5, 1.5 and 2 times higher in comparison with nonhydrolysed extract. Iron‐chelating and radical‐scavenging activity of O. biennis seedcake extract after hydrolysis (IC₅₀ = 0.076 mg mL^?1 and IC₅₀ = 0.050 mg mL^?1) was at a similar level as that nonhydrolyeed (IC₅₀ = 0.070 mg mL^?1 and IC₅₀ = 0.065 mg mL^?1). The antioxidant activity was two times higher after hydrolysis than before enzymatic hydrolysis of O. biennis seedcake extract. Also strong elastase inhibition activity has been shown to O. biennis seedcake extract before (IC₅₀ = 0.095 mg mL^?1) and after enzymatic hydrolysis (IC₅₀ = 0.07 mg mL^?1), respectively. Oenothera biennis and B. officinalis seedcake extracts before and after hydrolysis have stronger antibacterial activity against Pseudomonas aeruginosa strain in comparison with N. sativa seedcake.     

Development and validation of a SYBR‐Green I Real‐Time PCR test to detect bivalves including Mytilus species in foods

The incidence of allergy to seafood, and in particular to molluscs is second only to that of nuts. To protect consumers, the regulators of food products insisted on identifying molluscs as allergens. The aim was to develop quantitative assay for the presence Mytilus species in processed food products. The chosen platform was real‐time PCR (qPCR) targeting either the gene encoding mitochondrial cytochrome C oxidase I or the nuclear gene encoding β‐actin. Recombinant plasmids containing each of target regions were used as a reference for quantification purposes. Limit of detection (LOD) and of quantification (LOQ) were determined. Spiked food samples containing 50–500 μg g^?1 of Mytilus chilensis were analysed both by qPCR and by ELISA. The former assay gave a positive outcome over this range, whereas the latter was sensitive down to a concentration of 125 μg g^?1.     

The revised COLIPA in vitro UVA method

A multicentred study derived from the COLIPA in vitro UVA method was performed to assess the influence of test conditions on UVA protection factor (UVAPF) values in terms of amplitude, reproducibility between laboratories and correlation with in vivo UVA results. Eight products with a range of in vivo UVAPF from three to 29 were used. Two different types of plates, namely high‐roughness (5 μm) and low‐roughness (2 μm) plates, were used with a different application rate for each (1.3 mg cm^?2 and 0.75 mg cm^?2 respectively). The UVR dose applied to both plate types followed the same principle as the original test (1.2 J. cm^?2 × UVAPF0). Strong, significant correlations between in vitro and in vivo UVAPF values were observed for both plate types (Pearson correlation > 0.9, P ≤ 0.01). The correlation and slope obtained with the low‐roughness plates confirmed the previous results obtained by COLIPA. Across all laboratories, higher UVAPF values were obtained on the high‐roughness plates (P < 0.01). Reproducibility of UVAPF values between laboratories was comparable between the two plate roughness values (low roughness, COV = 8%; high roughness, COV = 12%). Considering the in vitro/in vivo comparisons, a regression slope of 0.83 was observed for the low‐roughness plates, in comparison with a value of 1.05 for the high‐roughness plates. The accuracy of the method was improved, therefore, with the use of the high‐roughness plates. With a constraint to recommend the use of only one plate type in the COLIPA UVA in vitro Test, the high‐roughness plate was selected on an on‐going basis to limit variability of results and to provide better accuracy with in vivo data.     

Effect of technological practices on individual betalains and antioxidant activity of Columbian betalain‐rich raw materials

The effect of different technological practices on ulluco (ullucus tuberosus) and Opuntia dillenii has been scrutinised. Their stability at different pHs and temperatures of storage or processing over time was monitored. Our aim was focused on the determination of individual betalains and antioxidant activity, not previously conducted in conjunction with these raw materials. On the basis of the results, it could be asserted that the ullucus tuberosus and Opuntia dillenii were more suitable for being added to low‐acidic foods (pH 5 and 6), in the light of the higher values of betalains and antioxidant capacity (1.3‐fold higher compared with pH 4). With regard to the temperature, cold storage conditions (4 °C) were optimal to increase or maintain as possible the initial content of betalains and antioxidant capacity. After cooking (80 °C), the identified betalains completely disappeared, but the low‐acidic conditions (pH 6) favoured the greater antioxidant activity when kept at that temperature.     

Changes in degradation and phosphorylation level of titin in three ovine muscles during postmortem

The objective of this study was to investigate the degradation of titin and its phosphorylation level in three muscles from sheep. The MFI and pH from the longissimus lumborum (LL), semimembranosus (SM) and psoas major (PM) muscles were measured at 30 min, 1, 2, 7, 14, 21 and 28 days postmortem. Myofibrillar proteins were extracted, separated by SDS‐PAGE and quantified by phosphor‐specific staining. Phosphorylation of titin was predicted by Pro‐Q Diamond‐SYPRO Ruby staining. Two days after exsanguination, the pH and MFI of the PM were higher than those of the LL and SM muscles (P < 0.05). The sarcomere length of the PM muscle was also longer than that of the LL and SM muscle (P < 0.05). PM muscles had a highest phosphorylation level (P < 0.05) at 0.5 h postmortem and showed the greatest degree of titin degradation over 28 days. This suggests that phosphorylation of titin might accelerate its degradation.     

The effects of ratio of cow's milk to soymilk,probiotic strain and fruit concentrate on qualitative aspects of probiotic flavoured fermented drinks

The effects of proportion of cow's milk to soymilk (100:0, 75:25, 50:50, 25:75, 0:100), probiotic bacteria (Lactobacillus acidophilus LA‐5 or Lactobacillus casei L‐01) and natural fruit concentrates (strawberry, apricot, peach and pear) on quality characteristics of soy‐based probiotic drink were investigated. The parameters were analysed at the end of fermentation and during 21 days of storage at 5 ^°C. The highest viability was observed when the equal proportion of cow's milk and soymilk and L. casei was used (50:50‐CY). During chilled storage, the flavouring apricot had the highest stimulatory effect on the survival of L. casei in 50:50 treatment. In general, the treatment 50:50‐CY was realised as the best one overall.     

Antiglycation capacity and antioxidant activities of different pigmented Thai rice

This study investigated the antiglycation capacity and antioxidant activities of fifteen Thai rice varieties. Purple variety, Kum Rai showed the highest value of total phenolic content (245.06 ± 7.87 mg GAE/gram extract dry weight), DPPH radical scavenging activity (92.33 ± 0.49 mg Trolox/gram extract dry weight), ABTS radical scavenging activity (221.01 ± 0.25 mg Trolox/gram extract dry weight) and percentage inhibition of AGEs formation (82.03 ± 0.19%). We found that, total phenolic content and antioxidant activities (ABTS and DPPH assay) in rice varieties were highly correlated (P < 0.05) with their antiglycation capacity. These results indicated that the total phenolic content was responsible for antioxidant and antiglycation capacities of rice samples. This study is the first report on a correlation between anti‐AGEs capacity and antioxidant activities of Thai rice varieties. Our data have provided useful information for selection of rice varieties for the bioactive compounds that may improve the health of the aged and diabetic complications.