Mechanical properties of κ-carrageenan in high concentration of sugar solutions

While the mechanism of gelation of carrageenan in an aqueous environment, via a coil–helix transition followed by aggregation, is well accepted, its behaviour in highly concentrated sugar is still not well understood. Therefore, the effect of biopolymer and salt concentration on the gelling properties of κ-carrageenans in the presence of high concentrations of sugars was investigated rheologically. A solution of 1% κ-carrageenan in the presence of 10 mM KCl and 87.5% corn syrup did not form a measurable network whereas 1% κ-carrageenan in the presence of 10 mM KCl in aqueous solution forms a gel. Gelation was again observed as KCl concentration was increased to 40 mM KCl. An increase of κ-carrageenan concentration from 1 to 2% with 10 mM KCl present did not restore the capacity for gelation. The effect of type of the sugar solution was also investigated by substituting a corn syrup/glucose syrup mixture for the original corn syrup. In the presence of corn syrup/glucose syrup mixture and salt at concentrations higher than 40 mM KCl, a different gelation behaviour was observed: a gel structure was already present at high temperature and a glass transition was measurable at the lowest temperatures. We believe this study gives new insights into the molecular state of carrageenan in the presence of high concentrations of sugars.     

Adsorption kinetics of BSA at air–sugar solution interfaces as affected by sugar type and concentration

The influence of glucose, sucrose and fructose at concentrations ranging from 0 to 40 wt.% on the adsorption kinetics of bovine serum albumin (BSA) at air–aqueous solution interfaces at 20 °C was measured using drop shape analysis. The rate of adsorption of proteins decreased in the presence of sugars. The diffusion coefficient of BSA in 40 wt.% sucrose solutions, calculated from the initial period of protein adsorption, was two orders of magnitude lower than the diffusion coefficient of BSA dissolved in pure water. The decrease of the diffusion coefficient with sugar concentration (δD_eff/δc_sugar) was appreciably higher at low sugar concentrations (<10 wt.%). Diffusion coefficients in the presence of sucrose were smaller than in the presence of glucose or fructose. Results were attributed to an increase in solution viscosity, preferential interactions of sugars with protein surfaces and an increased hydrophilicity of protein surfaces due to preferential hydration.     

Study of nonenzymic browning in α-amino acid and γ-aminobutyric acid/sugar model systems

The reactivities, in nonenzymic browning, of γ-aminobutyric acid (GABA), a non-protein amino acid with wide natural occurrence and potential health benefits as it occurs in foods, and of the α-l-amino acids arginine, glutamic acid, glutamine, leucine, lysine, and phenylalanine were investigated by heating equimolar mixtures of glucose and the cited amino acids at 110 °C at pH 6.0 for different times (0–4 h). Linear regression analysis indicated that the colour development in a GABA/glucose mixture was slower than that of a lysine/glucose mixture and comparable to that of a phenylalanine/glucose mixture. High-performance anion-exchange chromatography (HPAEC) with integrated pulsed amperometric detection (IPAD) showed that the decrease in GABA levels (ca. 10% after heating for 4 h) as a function of heating time was smaller than that of glucose (ca. 30% after heating for 4 h). At the same time, glucose to fructose isomerisation took place. After 20 min of heating at pH 6.0, all mixtures showed a fructose peak, the area of which increased with heating time. However, after correcting for fructose isomerisation, glucose losses were still higher than amino acid losses. In contrast to its precursor glutamic acid, GABA was stable during heating of a solution containing it alone. Heating of GABA-containing d-sugar solutions (xylose, fructose, glucose, maltose and sucrose) showed that the relative order of colour yield was pentose > hexose > disaccharides. As well as glucose to fructose isomerisation, HPAEC–IPAD allowed monitoring of the different isomerisation reactions occurring, and also disaccharide hydrolysis in the different GABA/sugar mixtures.     

Biological activities of Maillard reaction products (MRPs) in a sugar–amino acid model system

The various biological activities of Maillard reaction products (MRPs) from sugar (fructose and glucose) and 20 amino acid model systems were evaluated. Colour development, in vitro antioxidant, α-glucosidase inhibitory, antihypertensive, and antiproliferative activities of aqueous solutions of MRPs produced by heating at 130 °C for 2 h were measured. The fructose–amino acid mixture showed higher UV-absorbance and browning intensity than the glucose–amino acid mixture. The fructose–amino acid model MRPs showed higher DPPH and ABTS radical scavenging and ACE inhibitory activities than the glucose–amino acid model MRPs. The α-glucosidase inhibitory effect of MRPs derived from fructose– and glucose–tyrosine showed higher α-glucosidase inhibitory activity than that of other MRPs. Sugar–amino acid model MRPs inhibited the growth of HCT116 colon cancer cell in a dose-dependent manner (from 0.5 to 1.5 mg/ml). Glucose MRPs showed slightly higher antiproliferative activity than fructose MRPs. In particular, sugar–tryptophan and –tyrosine MRPs exerted higher biological activities than the other MRPs.     

Time-dependent flow properties of starch–milk–sugar pastes

The time-dependent flow properties of starch–milk–sugar (SMS) pastes have been studied. The flow properties were assessed from the measurement of the shear stress versus time of shearing at constant shear rate. Corn and wheat starches were used in this study, while the sugars were glucose, sucrose, and fructose. The Weltman model was used to evaluate the flow properties of SMS pastes prepared under different conditions. SMS pastes heated at 95 and 85 °C exhibited a thixotropic behavior, while pastes heated at 75 °C behaved like a rheopectic fluid. It was noted that the thixotropy occurred at high shear stress (above 50 Pa), and the rheopexy occurred at low shear stress (below 45 Pa). The degree of thixotropy, as assessed by the Weltman model parameters, increased significantly with starch concentration, and with less pronounced effect with sugar concentration. The effect of sugar type on the degree of thixotropy of SMS pastes heated at 95 °C decreased in the following order: fructose>sucrose>glucose. The type of starch played a role in the time-dependent flow properties of the SMS paste, with a general conclusion that wheat starch had a greater degree of thixotropy than corn starch.     

Biological activities and physicochemical properties of Maillard reaction products in sugar–bovine casein peptide model systems

The purpose of this study was to evaluate the biological activities and physicochemical properties of Maillard reaction products (MRPs), derived from aqueous reducing sugar (ribose, galactose and lactose) and bovine casein peptide (BCP) model systems. The fluorescence intensity of ribose-BCP MRPs reached the maximum value within 1 h, while it took 3 h for galactose-BCP MRPs. Size exclusion chromatography of all the MRPs indicated molecular rearrangements and production of new smaller molecules, as a function of the heating time. The consumption of ribose and amino groups was the highest in the ribose-BCP MRPs. BCP lost its known angiotensin-I-converting enzyme (ACE) inhibitory activity by the Maillard reaction with reducing sugars. Ribose–BCP MRPs had the lowest ACE inhibitory activity, but they showed the highest 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging activity and ferrous reducing power among all the MRPs. Galactose-BCP MRPs inhibited, slightly the growth of Caco-2 cells, while ribose-BCPand lactose-BCP MRPs had no cytotoxicity.     

Study on formation of acrylamide in asparagine–sugar microwave heating systems using UPLC-MS/MS analytical method

Microwave heating can be regarded as a possible way to produce a considerable amount of acrylamide. The present study investigated the formation of acrylamide in asparagine–glucose, asparagine–fructose and asparagine–sucrose microwave heating systems by the response surface methodology (RSM) and the orthogonal array methodology (OAM). The acrylamide content was rapidly quantified by a validated ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method. Results of RSM study indicated that in the asparagine–glucose system, the acrylamide content increased in the combined condition of high temperature accompanying with short heating time (>190 °C, <20 min) or low temperature accompanying with long heating time (<180 °C, >30 min). In the asparagine–fructose system, the similar conclusion was made in the combined condition of high temperature accompanying with short heating time (>175 °C, <20 min) or low temperature accompanying with long heating time (<170 °C, >25 min). In the asparagine–sucrose system, the amount of acrylamide enhanced with the increase of both heating temperature and heating time. The fitted mathematic models were successfully applied to the quantification of acrylamide formation when the heating temperature and heating time fell into the ranges of 120–240 °C and 5–35 min simultaneously. OAM study showed that acrylamide is readily formed via heating binary precursors 5 min at 180 °C in the asparagine–glucose and asparagine–fructose systems. However, acrylamide is readily generated when the binary precursors are heated 15 min at 180 °C in the asparagine–sucrose system.     

Effect of water activity on sugar crystallization and β-carotene stability of freeze-dried mango powder

Storage water activity (a_w) affects the stability of freeze-dried food. The sugar crystallization and storage stability of β-carotene in freeze-dried mango powder was investigated following storage under various relative vapor pressures (11.3-80.9%). Sugar crystallization was revealed by the loss of sorbed water in the water sorption experiment. However, the sorption isotherms showed unclear divergence between the experimental and predicted values. X-ray powder diffraction and scanning electron microscopy were used to confirm the crystallization. The results showed that increased a_w resulted in higher sugar crystallization. The loss of β-carotene was monitored by high-performance liquid chromatography with a diode-array detector and fitted to a first-order reaction. The rate constant decreased as a_w increased up to 0.43, due to the collapse of the mango powder. An increase in the rate constant above this value of a_w coincided with pronounced sugar crystallization. Choosing the appropriate value of a_w for storage can prevent sugar crystallization and enhance β-carotene stability in freeze-dried fruit powder.     

Solutions properties and solute–solvent interactions in ternary sugar–salt–water solutions

Viscometric constants were used to provide information on solute–solvent interactions in ternary water–sugar–salt solutions. Comparison was made between pure water and aqueous salt solution as solvents affecting the behaviour of small carbohydrates. The determination of intrinsic viscosity was made more accurate by applying triple extrapolation of the three equations (Huggins, Kramer and Meffroy-Biget). Results obtained with this triple extrapolation method were compared to that obtained with the Jones–Dole equation usually used. The B coefficient of the Jones–Dole equation was interpreted in terms of its components (B_size) and (B_structure), respectively assigned to the hydrodynamic volume and the contribution to solvent structural change. The determination of the apparent molar volumes in pure water enabled calculation of the hydration numbers. The determined apparent molar volumes of the studied sugars in aqueous salt solutions suggested a dehydration of the sugars explained by sugar–salt interactions. The most important perturbations observed in LiCl solutions compared to those in NaCl solutions were explained by LiCl being surrounded with more water molecules.     

Effect of Maillard reaction conditions on browning and antiradical activity of sugar–tuna stomach hydrolysate model system

The antiradical activity of Maillard reaction products (MRPs) made from sugar–tuna stomach hydrolysate model system was tested. The antiradical activity of the MRPs derived from ribose was 11-fold higher than that of MRPs derived from glucose due to the acyclic form of the ribose. The activity reached the plateau at a 30 mg/mL ribose concentration. The ribose caramelization contributed to the antiradical activity and browning reactions at 95 °C and 115 °C. The increase in DPPH radical scavenging of MRPs is attributed not only to the temperature but also to the buffer type and buffer concentration. Phosphate buffer showed the most efficient compared to citrate or Tris–HCl buffers. A positive correlation (R² = 0.98) was observed between the antiradical activity, the browning and the phosphate concentration. The MRPs obtained under these mild experimental conditions exhibited no toxicity towards Vero cells and 3T3 cells, despite their high antiradical activity.     

Effect of co-inoculation of Saccharomyces cerevisiae and Lactobacillus fermentum on the quality of the distilled sugar cane beverage cachaça

Abstract: The effect of Lactobacillus fermentum in co‐inoculation with Saccharomyces cerevisiae UFLA CA11 on the quality of cachaça (sugar cane spirit) was evaluated. The co‐inoculation was first evaluated in flask fermentation, and subsequently, yeast and bacteria were co‐cultured at approximately 10⁵ CFU/mL and 10⁸ CFU/mL, respectively, in 4 consecutive batches. L. fermentum did not affect the growth or activity (sugar consumption and fermentation rate) of S. cerevisiae UFLA CA11 during fermentation. The physicochemical analysis revealed a higher concentration (Tukey test) of aldehydes (22.07 mg/100 mL anhydrous alcohol) in cachaça produced by co‐inoculation. Analysis of volatile compounds using GC‐FID demonstrated that cachaça produced by co‐inoculation had higher concentrations of acetaldehyde (25.15 mg/L), ethyl acetate (30.17 mg/L), and 2,3‐butanedione (170.39 μ/L), while cachaça produced by UFLA CA11 contained higher concentrations of ethyl lactate (1205.98 μ/L), propionic acid (127.97 μ/L), butyric acid (2335.57 μ/L), and 1‐pentanol (469.23 μ/L). The lowest concentration of acetic acid measured by HPLC was found in cachaça obtained with UFLA CA11. The sensory analysis, performed using the Mann–Whitney test, revealed that cachaça produced by co‐inoculation differed from that produced by UFLA CA11 in taste and aroma. Practical Application: This study reports on the use of a mixed culture of Saccharomyces cerevisae and Lactobacillus fermentum to produce cachaça and shows the influence of co‐inoculation of yeast and bacteria on the quality of this beverage.     

Acrylamide in Caribbean foods – Residual levels and their relation to reducing sugar and asparagine content

The acrylamide levels in commercial and homemade Caribbean foods were determined by pre-derivatisation of acrylamide to 2-bromopropenamide and analysed by gas chromatography with mass spectrometric (GC/MS) detection. Over 100 Caribbean food samples were analysed for the presence of acrylamide. These samples include: biscuits, breakfast cereals, banana chips and home-prepared foods: breadfruit; Artocarpus altilis, banana fritters, and dumplings. The limit of detection (LOD) for the GC/MS method was found to be dependent on the type of column used for the GC/MS analysis. The DB-1701 and the DB-VRX columns gave LODs of 20 and 4 μg/kg, respectively. Acrylamide has not been found in raw foods or foods which have been cooked by boiling. Its content in all other foods had concentrations in the range, 65–3640 μg/kg. The relationship between acrylamide levels and precursor concentration as well as the health implications of our findings are discussed.     

Changes in quality of rainbow trout (Oncorhynchus mykiss) fillets preserved with salt and sugar at low concentrations and stored at 4°C

The effects of dry-curing with low concentrations of salt and sugar on the quality of rainbow trout (Oncorhynchus mykiss) fillets were studied over a 16-day storage period at 4°C. Physicochemical characteristics (total volatile base nitrogen (TVB-N), biogenic amines (BAs), ATP-related compounds and K value), microbial populations (total aerobic counts (TAC), H₂S-producing bacteria, Pseudomonas, Aeromonas, and lactic acid bacteria) and sensory (SA) indicators were analyzed. Fish samples were subjected to the following treatments: untreated (control), dry-cured with 1.3% salt (T1), and dry-cured with 1.3% salt that also contained 0.9% sugar (T2). SA indicated that the sensory quality of the control, T1, and T2 was unacceptable after 8, 12, and 12 days of storage, respectively. Moreover, the cadaverine concentration of treated samples was significantly lower (P < 0.05) than the control after storing for 8 days. T1 and T2 were significantly higher (P < 0.05) than the control in inosine 5-monophosphate (IMP) content from the 2th to 10th day. Cadaverine, putrescine, hypoxanthine, and TAC were correlated significantly (P < 0.01) with SA, and these seemed to be reliable indicators of fish quality. The results indicated that curing treatments extended the shelf life of rainbow trout fillets, which could be exploited by processors.     

Role of precursors on the kinetics of acrylamide formation and elimination under low moisture conditions using a multiresponse approach – Part I: Effect of the type of sugar

The effect of type of sugar on the kinetics of acrylamide formation and elimination reactions was investigated under low moisture conditions using equimolar asparagine–sugar model systems, heated at temperatures between 120 and 200 °C. The monosaccharides glucose and fructose and the disaccharide sucrose were selected to study this effect. A mechanistic model was used as a basis for multiresponse modelling of the different responses measured (acrylamide, glucose, fructose, sucrose, asparagine, aspartic acid and melanoidins). In spite of the higher acrylamide yield per mol initial asparagine for sucrose over fructose to glucose, the kinetic parameters estimated for acrylamide formation revealed that the type of sugar, monosaccharide or disaccharide, had only a limited effect on this reaction. The corresponding activation energy, however, was significantly lower in case the disaccharide sucrose was added. An opposite trend was observed for the acrylamide elimination rate constant, being significantly higher for the system with sucrose, whereas the temperature dependence of this rate constant remained unaffected by the type of sugar available under the reaction conditions considered.     

Role of Disinfection in Food Industry

In industrialized countries, the epidemiology of infec- tious diseases with indirect transmission through water and foodstuffs has undergone considerable changes over the past decades with the almost total disappearance of some traditional pathogen microo…     

Effects of prepartum supplementation of β-carotene in Holstein cows

Whether supplemental dietary β-carotene affects periparturient cows and vitamins A and E in cows when dietary vitamin A is adequate remains uncertain. Our objective was to assess the effect of β-carotene supplementation during the close-up dry period in a herd with adequate status of vitamins A and E but low in β-carotene. The study was conducted on a large commercial dairy farm in Indiana during early summer of 2015. Ninety-four multiparous Holstein cows were assigned to either control (CON; n = 47) or β-carotene (BC; n = 47) treatments. When locked in headgates each morning, each cow received a topdress of β-carotene (Rovimix, 8 g/d; provided 800 mg of β-carotene) or carrier from 21 d before expected calving until calving. Blood samples were collected at 21 ± 1 d (mean ± standard deviation) before expected calving (before treatments began), 7 ± 1 d before calving, immediately following parturition, and 7 ± 1 d postpartum. Blood serum was analyzed for vitamins A and E, β-carotene, cholesterol, and other metabolites and enzymes. Data were analyzed using the MIXED procedure in SAS (SAS Institute Inc.). Cows had low β-carotene concentrations (0.85 μg/mL) in blood serum before treatments began. Compared with CON cows, BC cows had higher overall mean concentrations of β-carotene (2.87 μg/mL vs. 0.73 μg/mL) and retinol (165 vs. 143 ng/mL). Cows fed BC had lower α-tocopherol in serum than cows fed CON (2.26 vs. 2.46 µg/mL). Cows fed BC had lower peak milk than cows fed CON (50.9 vs. 55.3), but total lactation milk yield did not differ significantly. No effects of BC were observed on days to conception (100 d) or times bred (2.4). Treatments did not affect incidences of ketosis, retained placenta, displaced abomasum, off feed, lameness, footrot, mastitis, or metritis. In conclusion, in pregnant cows already receiving adequate vitamin A but with low serum β-carotene concentration, supplementation of β-carotene increased concentrations of β-carotene and vitamin A in blood serum, but did not affect production, reproduction, or health.     

Mechanical-electrical Integration of Textile Machinery in China

Recently, leading textile machinery manufacturers in Chinahave adjusted their strategy to a market-oriented and profit-based one. They spent greater efforts on technical innovation,aimed at improving the mechanical-electrical integration levelof textile machinery and making them more competitive on amarket requiring small batch, diversified variety and quickresponse. As a result, they have developed a batch of high-quality new textile machinery that can adapt to the need onmarket. These produc…