A reference isotope dilution headspace GC/MS method for the determination of nitrite and nitrate in meat samples

A novel method for the determination of nitrite and nitrate in meat products is presented. The samples were ground and extracted in hot water with the presence of and internal standards. The solution was buffered with sodium bicarbonate and reacted with triethyloxonium tetrafluoroborate to convert nitrite and nitrate into EtNO₂ and EtONO₂. Such derivatives could be detected by headspace GC/MS in positive chemical ionisation mode with 0.05 µg g⁻¹ and 1.0 µg g⁻¹ LOD. The method was used for and quantitation in the 0.5-300 and 2.5-300 µg g⁻¹ ranges. The method was applied for the analysis of fifteen meat products. Despite minimal sample preparation, the headspace sampling ensured a clean chromatography for over 135 analyses (throughput ten samples per hour). The proposed method offers selective GC/MS detection combined with high-precision isotope dilution calibration, it is suitable for metrological applications and can support regulations on meat safety (European Commission, 2011).     

Inactivation efficacy of plasma-activated water: influence of plasma treatment time,exposure time and bacterial species

This study aimed to evaluate the influence of plasma treatment time, bacterial exposure time to PAW and bacterial species on the inactivation efficacy of plasma-activated water (PAW), with additional investigation of the inactivation mechanisms of PAW. Six bacterial species, including Listeria innocua, Staphyloccus aureus, Escherichia coli, Pseudomonas fluorescens, Shewanella putrefaciens and Aeromonas hydrophila were selected as the representative bacteria. The initial bacterial concentration was around 7 log CFU ml⁻¹ after mixing with PAW, and the inactivation efficacy was measured after different exposure times during the 4 °C storage. Scanning electron microscopy (SEM) images of the bacteria after PAW treatment were carried out to inspect the cell structure damage, and physicochemical properties of PAW, including pH, conductivity and long-living reactive species of H₂O₂, , and , were examined. The results showed that the inactivation efficacy of PAW was positively correlated with plasma treatment time and bacterial exposure time, and for the species examined in this study, the Gram-negative species were more sensitive to PAW than the Gram-positive species. Cell structure damage, including shrinkage, distortion, or holes, was observed after PAW treatment. The pH of PAW was acidified to 2.5–2.9, and conductivity was significantly increased to 518.0 μs cm⁻¹. and H₂O₂ were reduced during the 48 h storage, while an increased concentration was observed for . This study demonstrated that the processing parameters of plasma treatment time, exposure time and characteristics of bacteria can significantly affect the inactivation efficacy of PAW.     

Phenolic profile and changes in the antioxidant activity of crabapple (Malus domestica cv Royalty) fruit during maturation on the tree

The fruits of crabapple (Malus domestica cv Royalty) harvested at six times during fruit maturation on the tree (60, 80, 100, 120, 140 and 160 day after full bloom, DAFB) were evaluated for their antioxidant potentials by various assays such as DPPH, ABTS, superoxide anion, hydroxyl radical and ferric reducing power. Total phenolic and flavonoid were analysed and characterised using HPLC‐DAD‐MS/MS. Results showed that the Royalty fruits harvested on 60 DAFB had the strongest scavenging activity against DPPH, ABTS and radicals ( = 0.37 mg mL^?1,  = 0.19 mg mL^?1 and  = 4906.63 U L^?1) and ferric reducing power (FRAP = 2.85 mol Fe²⁺ per kg dw), which highly correlated with its high amount of total phenolics of 130.17 mg gallic acid equivalents (GAE) per gram dry weight and total flavonoid of 866.15 mg rutin equivalents (RE) per gram dry weight. Eight phenolic compounds were identified in the Royalty extract of 60 DAFB as caffeic acid, eriodictyol rhamnoside, phloretin hexoside I, coumaroyl guinic acid, quercetin hexoside, phloretin hexoside II, quercetin pentoside and quercetin rhamnoside. These findings suggest that Royalty could be potentially used as a promising source of natural antioxidants in the development of functional foods.     

Modelling growth of Lactobacillus plantarum and shelf life of vacuum‐packaged cooked chopped pork at different temperatures

Lactobacillus plantarum growth in a vacuum‐packaged cooked meat product under different storage temperatures (4, 10 and 16 °C) and the relation between the microorganism growth and sensory quality were investigated. The Gompertz model was fitted to experimental counts of L. plantarum showing a good fitting to growth curves at different temperatures. A root‐square secondary model and linear model were satisfactorily fitted to estimated growth rates () and lag times (), respectively. The sensory attributes (colour, flavour, taste, appearance) were also evaluated due to their importance to the global quality (Q). The sensory deterioration was detected several days after L. plantarum reached the stationary phase, that is, 59, 45 and 25 days for 4, 10 and 16 °C, respectively. According to results, sensory deterioration was related to time when microorganism reached late stationary phase, phenomenon known as ‘delayed change’.     

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.     

Real-time quality authentication of honey using atmospheric pressure chemical ionisation mass spectrometry (APCI-MS)

The aim of this study was to use gas chromatography-mass spectrometry (GC-MS) and APCI-MS techniques to detect adulteration in honey. The key volatile compounds in the headspace of the adulterated honey were marked by GC-MS and their representative fragment ions were utilised in scanning honey samples using the real-time APCI-MS system. The PLS models validated using independent data sets resulted in coefficient of the determination () of 0.97 and 0.96 and root mean square error in prediction (RMSEP) of 2.62 and 2.45 for the GC-MS and APCI-MS data sets respectively. The most efficient volatiles from GC-MS analysis and their corresponding fragment ions m/z from APCI-MS data analysis were then identified and used to develop new PLS models to predict the level of adulteration. The best PLS model gave of 0.95 and RMEP of 2.60% in the independent validation set indicating that the model was very accurate in predicting the level of adulteration.     

Acid-induced aggregation and gelation of heat-treated chia proteins

This work studied for the first time the acid-induced aggregation and gelation of heat-treated chia protein isolates obtained by extraction at pH 10 or 12 (CPI10 and CPI12, respectively). The aggregation state of proteins was modified during acidification. The size of the aggregates was reduced for both samples when the pH decreased but below pH 4.5 further protein aggregation took place for CPI12. Gelation of CPI12 was completed after about 30 min of acidification with glucone-δ-lactone. By contrast, this period was not enough to reach a constant value in G′ for CPI10. When gelation was ensured, confocal laser scanning micrographs from those gels revealed a coarse and irregular structure with large pores (median size of diameters: 30 μm). Instead, micrographs from CPI12 cold gels showed a more regular and interconnected network, with smaller pores (median size of diameters: 9 μm). These differences are consistent with a higher elastic behaviour ( = 13.6 ± 0.1 Pa).     

Stenocereus griseus (Haw) pitaya as source of natural colourant: technological stability of colour and individual betalains

Stenocereus griseus pitaya has been evaluated as potential natural colourant on the basis of tristimulus colorimetry, differential colorimetry, and individual betalains, not previously conducted in conjunction with this raw material. Different technological treatment conditions were reproduced based on different pHs, temperatures and storage time. According to the results, cold temperatures (4 °C) maintained for longer the initial colour characteristics (L*, and h_ab) of the extracts, whereas h_ab modifications began from the commencement of treatment at room temperature. Highly acidic extracts (pH 4) were the most stable samples in the light of the lower h_ab and changes over time, even at room temperature. Betanin, isobetanin, betanidin and 2-decarboxy-neobetanin were more affected by temperature, whereas the content of the minor betalains significantly (P < 0.05) varied when pH was modified. Moreover, visually appreciable and quantitative colour changes (Δ > 3) were observed among all pH values and temperatures.     

Powdered barley sprouts: composition,functionality and polyphenol digestibility

This study was performed to evaluate the phytochemical composition, in vitro antioxidant capacity, antihyperglycaemic and anti‐inflammatory activities, and simulated gastrointestinal digestion of 7‐day‐old freeze‐dried barley sprouts (BS), one hybrid and one nonhybrid variety: ‘NS565’ (BSNS) and ‘Golozrni’ (BSG), respectively. BSNS expressed significantly higher (P ≤ 0.05) content of total phenols, chlorophyll and carotenoids. Phenolic compounds were the most dominant bioactives in both BSNS and BSG (713.25 and 479.02 mg GAE 100 g^?1 DW, respectively). BSNS possessed significantly higher (P ≤ 0.05) antioxidant capacity, evaluated by DPPH and ABTS assays, and reducing power ( = 0.54 mg mL^?1; IC₅₀^ABTS = 0.79 mg mL^?1; RP_0.5 = 9.35 mg mL^?1). Antihyperglycaemic and anti‐inflammatory activities of BSNS ( = 1.43 mg mL^?1;  = 1.86 mg mL^?1) were also significantly higher (P ≤ 0.05) than BSG ( = 1.97 mg mL^?1;  = 4.40 mg mL^?1). In vitro simulation of gastrointestinal digestion showed higher release of phenolic compounds in intestinal fluid than in gastric fluid.     

Fast and non-destructive determination of simultaneous physicochemical parameters of Manihot esculenta flour using FT-NIR spectroscopy and multivariate analysis

Manihot esculenta flour (MEF) is the main energetic source for a major part of the population in the Amazonian region. In this study, near-infrared spectroscopy (NIRS) was used, for the first time, to predict physicochemical parameters of MEF. The water activity (a_W), ash content, bulk density, moisture content, pH, geometric mean diameter (GMD) and colour parameters of L*, and h_ab were determined for 106 samples of MEF. Calibration equations with independent validation were developed to predict all parameters using the partial least square regression method. The performance of models was evaluated by the root mean standard error of calibration (RMSEC) and validation (RMSEV), and R² values. The a_W (RMSEC = RMSEV = 0.05), moisture content (RMSEC = 0.35%; RMSEV = 0.45%) and pH (RMSEC = 0.16; RMSEV = 0.18) could be predicted (R² > 0.727) by NIRS coupled to multivariate analysis. NIRS and multivariate analysis proved to be a powerful tool to predict multiple physicochemical parameters of MEF.     

High hydrostatic pressure inactivation kinetics of the endogenous lipoxygenase in crude silver carp (Hypophthalmichthys molitrix) extract

Inactivation kinetics of endogenous lipoxygenase in crude silver carp (Hypophthalmichthys molitrix) extract was studied for thermal (50–80 °C, ambient pressure) and high hydrostatic pressure combined with heat treatment (300–700 MPa at 50–80 °C) process conditions. Lipoxygenase (LOX) inactivation followed first‐order kinetics at all pressure–temperature combinations used. Moreover, LOX inactivation rates became less pressure dependent with increasing pressure at all temperatures studied and also showed less temperature dependence of the enzyme inactivation rate at various high pressure levels tested. It is evident that inactivation kinetics is complex affected by both pressure and temperature. Therefore, response surface methodology (RSM) was attempted to investigate combined temperature–pressure processing conditions on LOX inactivation kinetics in crude silver carp extract samples. In conclusion, the LOX inactivation rate constant was modelled as a function of both temperature and pressure conditions by a quadratic polynomial equation as follows: .     

Effect of pre-gelatinised high-amylose maize starch combined with Ca2+ -induced setting of alginate on the physicochemical and sensory properties of rice flour noodles

This study explored the effect of pre-gelatinised high-amylose maize starch combined with Ca²⁺ -induced setting of alginate on the physicochemical and sensory properties of rice flour noodles. Rice flour noodles were prepared by partially substituting rice flour with pre-gelatinised high-amylose maize starch in ratios of 5, 10 and 15% (wt/wt), combined with sodium alginate at 1% (wt/wt). The noodles were then immersed in a calcium chloride solution to set the alginate. Results indicated that the hydrocolloids significantly (P < 0.05) increased noodle tensile strength, hardness, water absorption and optimum cooking time while cooking loss was significantly (P < 0.05) reduced. SEM micrographs showed a denser, compact noodle structure with an increase in the matrix's continuity as a result of hydrocolloids addition. Formulated noodles also scored above average (5.91) sensory acceptability on the 7 points hedonic scale. Overall, results proved promising for the preparation of rice flour noodles with enhanced properties.     

Impact of wheat bran addition on the temperature‐induced state transitions in dough during bread‐baking process

Wheat bran‐mediated effects on temperature‐induced state transitions of proofed bread dough were studied as function of its level of replacement (5%–15%) to wheat flour. Proofed dough was subjected to rheological tests at small deformations. During heating of proofed dough from 30 °C to 95 °C, the value of elastic modulus (G′) attained its maximum at a temperature () that represented peak gelatinisation temperature (T_P). Dough with 15% bran depicted significant increase in T_P over other formulations. Bran addition increased glass transition temperature (T_g) of dough and suppressed drop in elastic modulus (G′) at T > T_g. The above events resulted in decreased loaf‐specific volume and increased crumb hardness. The former was caused by retarded bubble expansion during initial stages of baking, explained by reduced uniaxial and biaxial extensibilities of dough. Mean bubble size depicted an inverse relationship with the hardness of breadcrumb.     

Effects of state/phase transitions on the quality attributes of mango (Mangifera indica L.) during frozen storage

Effects of different state/phase transitions (temperature fluctuations) on quality attributes of mango cubes during frozen storage were investigated. Temperature of frozen mango was modulated from ?65 °C to different states, namely, rubbery state , partially freeze‐concentrated state () and glassy states ( and ). Results revealed that frozen samples after 4 weeks of storage in a glassy state showed higher quality in hardness, drip loss, colour and ascorbic acid. Quality of mango still continued to change during frozen storage even in the glassy state without temperature fluctuations. Furthermore, there was a significant decrease in quality attributes of frozen mango subjected to temperature fluctuations above and . Current work indicates glassy state storage can improve retention of quality attributes in frozen mango and glassy state without temperature fluctuation was proposed as the most favourable frozen storage condition.     

Studies on noodle quality of potato and rice starches and their blends in relation to their physicochemical, pasting and gel textural properties

The physicochemical, pasting, and gel textural properties of potato and rice starches and their blends were studied in relation to their noodle making performance. Amylose content, swelling power and solubility values of potato starch were significantly (P ≤ 0.05) higher than for rice starch. Pasting properties showed higher peak, final and setback viscosity for potato starch as compared to rice starch. Texture profile analysis revealed that potato starch gel had higher hardness, cohesiveness and chewiness as compared to rice starch gel. Potato starch noodles showed higher cooked weight and cooking loss and were scored higher by sensory panellists especially with respect to transparency and slipperiness. On the other hand, rice starch noodles were more firm with lower cooking loss. Addition of potato starch to rice starch significantly (P ≤ 0.05) affected the noodle characteristics. Among the starch blends studied, blending of potato and rice starch in the ratio of 1:1 resulted in good quality noodles in terms of their lower cooking time, higher cooked weight, transparency and slipperiness. The results revealed the possibility of blending of potato starch with rice starch in equal proportions to produce noodles of acceptable quality.     

Study on the water state,mobility and textural property of Chinese noodles during boiling

The water mobility, state and textural properties of Chinese fresh noodles (CFNs) and Chinese dried noodles (CDNs) made from same wheat cultivar were measured during boiling using low-field nuclear magnetic resonance (LF-NMR), low-field nuclear magnetic Imaging (LF-NMI) and a textural analyser. ‘The oil immersion method’ was applied to gain the clear images from LF-NMI measurement. The distributions of the three water states (T₂₁, T₂₂ and T₂₃) in the noodles were distinguished. The results indicated that water mobility in noodles was closely related to the gelatinisation of noodle starch. Compared with CFNs, CDNs need a longer cooking time for water mobility and starch gelatinisation. The results of the cooked noodle profiles showed that the cooked CDNs (8 min) had an undesirable textural properties compared with the cooked CFNs (2 min). The longer cooking time of CDNs is responsible for its undesirable texture since the textural properties change during the longer cooking time.     

Effect of heat-moisture treatment for utilization of germinated brown rice in wheat noodle

Effect of heat-moisture treatment of germinated brown rice (GBR) on the texture and cooking quality of the noodles containing mixtures of wheat and GBR flours was investigated. With the increase in GBR content, hardness and tensile strength of the composite noodles decreased and cooking loss and water absorption increased. Pasting viscosity of the flour mixtures was significantly decreased by increasing the amount of GBR. Heat-moisture treatment of GBR (17 or 20 g/100 g moisture at 100 °C for 4 h), however, apparently increased the pasting viscosity and improved the texture and cooking quality of the composite noodles. The mixture of wheat and a treated GBR (1:1 weight ratio) showed a pasting viscosity similar to pure wheat flour. The noodle containing the heat-moisture treated GBR flours showed the lower cooking loss, and higher hardness and tensile strength than the noodle containing untreated counterparts. Among the treated GBR flours tested, the GBR treated at 100 °C for 4 h at a moisture level of 17 g/100 g was the most acceptable in terms of cooking quality and textural property, close to those of the noodle of pure wheat flour. Substitution with the heat-moisture treated GBR, however, made the noodle darker because of thermal discoloration of GBR.     

Suitability of pigeon pea and rice starches and their blends for noodle making

The physicochemical and pasting properties of pigeon pea and rice starches were studied to assess their suitability for noodle making. Amylose content, solubility and freeze thaw stability of pigeon pea starch were significantly higher than those of rice starch (p < 0.05). The pasting properties of peak viscosity, final viscosity, breakdown and set back showed higher values for pigeon pea starch, whereas hot paste viscosity and pasting temperature were higher for rice starch. Rice starch noodles revealed less cooking time (4 min) and less percent solids loss, whereas pigeon pea starch noodles had higher cooking time (12 min), higher percentage of water absorbed during cooking, more hardness and cohesiveness. Rice starch noodles scored higher for their transparency and slipperiness over pigeon pea starch noodles. Blending of pigeon pea starch with rice starch had significant effects on the cooking and sensory quality of noodles. Among starch blends, 70:30 blend of the pigeon pea and rice starches respectively resulted in good quality of noodles especially in terms of their higher transparency, slipperiness, overall acceptability and cohesiveness values. Blending of pigeon pea starch with 30% rice starch could produce noodles with superior quality as compared to native pigeon pea and rice starch noodles.     

The influence of ultrasonic modification on arabinoxylans properties obtained from wheat bran

This work is concerned with modification of wheat bran arabinoxylans by ultrasound irradiation. The average molecular weights of arabinoxylans ranging from 580 000 to 800 000 kDa were yielded by regulating ultrasonic powder (120–480 W) and treat time (15–45 min). The phenolic compounds increased after ultrasound treatment, and arabinose‐to‐xylose ratios ranged between 0.55 and 0.67. FTIR spectroscopy revealed that the major chemical composition of arabinoxylans was unchanged. The maximum storage modulus decreased with the extension of ultrasonic treatment time. The antioxidant capacity test showed that the EC₅₀ values decreased and the values from the ferric reducing antioxidant power decreased after ultrasound treatment. The results suggested that ultrasound is an effective method for the modification of arabinoxylans.