A method for the determination of acrylamide in bakery products using ion trap LC-ESI-MS/MS

Acrylamide levels of bakery products, e. g., bread and bread rolls, are usually below 100 microg/kg , often even below 50 microg/kg. Therefore, usual analytical methods which have an LOQ greater, not dbl equals 25 microg/kg are not sensitive enough for detailed investigations on acrylamide formation within these commodities. An improved method for trace level determination of acrylamide in bakery products was developed using ion trap LC-ESI-MS/MS. Samples were divided into crumbs and crusts to achieve an initial concentration by removing the crumbs since these are devoid of acrylamide. After sample extraction and clean-up using multimode SPE cartridges, further analyte enrichment was accomplished by solid-phase-supported liquid-liquid extraction with ethyl acetate prior to LC-MS/MS analysis. The method was evaluated using bread, bread rolls, alkali-baked bread rolls, and toast. LOQ was calculated from the confidence interval of the calibration curve and found to be 1.7 ng/mL, corresponding to 17 microg/kg of product. When crumbs and crusts were separated, an LOQ of 10.2 microg/kg of bakery product could be obtained. As demonstrated in preliminary comparative analyses, accuracy of the method met the requirements for determination of trace level acrylamide formation in bakery products. Mean recovery was 102.4% (CV 4.5%), intermediate reproducibility revealed a CV of 2.1%, and a repeatability of CV 6.0%.     

Effect of radiofrequency heating on acrylamide formation in bakery products

This work was addressed to study the influence of radiofrequency (RF) heating on acrylamide (AA) formation in bakery products. To this purpose, leavened cakes and short dough biscuits were baked to a final moisture of 3.5 and 3.0%, respectively, by means of conventional convection heating or different combinations of conventional and RF heating. Results showed that, with respect to the baking process entirely carried out in an air-circulating oven, the RF-assisted baking process, i.e. the application of RF heating in the last stages of the baking process, resulted to be a promising strategy to keep low the AA levels in the bakery products. In particular, the best results were obtained for products which were moved from the hot-air baking to the RF heating when their residual moisture was still fairly high (around 10%). Results also suggested that, when very low values of residual moisture are required, this technological intervention is more suitable to thin bakery products, such as biscuits, than to thick products, such as leavened cakes, because of excessive browning in the internal portion as a consequence of the RF heating.     

Characterization of the Maillard reaction in bread crisps

Maillard reaction (MR) is one of the main chemical event occurring during baking. To study the reaction in bakery products, a dry model system is more useful than an aqueous one. In this work, the effects of formulation and processing conditions in a crisp bread system were investigated to test the effects of different additives on both the overall reaction and the formation of MR products such as 5-hydroxymethyl-2-furaldehyde (HMF) and acrylamide. Cylindrical dough made up of flour, water and yeast was baked at 180 °C for 35 min and the slices were toasted at different times/temperatures combinations. Browning and water content were monitored along with the kinetic of formation of chemical indicators such as HMF and acrylamide also calculating rate constants and activation energy. These parameters were also monitored in systems added with glycine and asparaginase. During toasting water content follows an exponential trend, being the rate of water loss faster in the initial stage of toasting and at higher temperature. Browning was more intense when toasting at higher temperature and a linear correlations between browning (ΔL*, ΔE*), HMF and acrylamide concentration were observed when toasting at 180 °C. HMF and acrylamide content increased with the toasting time and temperature. Their concentrations were strongly dependent on the water content of the final product, and both the addition of glycine and asparaginase are effective in reducing acrylamide content. The addition of glycine enhanced the browning of toasted bread, and slightly increased HMF content at any toasting temperature. The system characterized in this work represents a suitable tool to study the development of the MR in dry systems.     

Performance and fatty acid profiling of interesterified trans free bakery shortening in short dough biscuits

Short dough biscuits were prepared using interesterified trans free bakery shortening (IETFS). Hydrogenated shortening (HS) based biscuits were prepared as a control. The diameter, height and spread ratio were determined. Biscuits were analysed up to 8 months for hardness, moisture and acidity of the extracted fat. IETFS biscuits were significantly (P < 0.05) less hard, had a higher spread ratio and were rated higher on all sensory attributes. Their overall acceptability score on a nine point hedonic scale was 8.2 ± 0.8 as compared to 7.3 ± 0.7 for control biscuits. The fatty acid fraction of control biscuits was: saturated fat, 51.6%; trans fat, 14.5%; monounsaturated fat, 28.0%; and polyunsaturated fat, 5.9% and that of IE trans free biscuits was: saturated fat, 54.8%; trans fat, 0.6%; monounsaturated fat, 38.1%; and polyunsaturated fat, 6.5%. The IETFS was found to be appropriate as an alternate to hydrogenated shortening, providing both functionality and nutritive advantage in biscuits.     

Controlled delivery of propionic acid from chitosan films for pastry dough conservation

A study was undertaken to evaluate the feasibility of using chitosan active films designed to control the release of an antimicrobial agent. In this context, the efficacy of propionic acid as both a medium for chitosan dissolution and an antimicrobial agent was examined. This work was focused on studying the potential application of chitosan active films developed to conserve a pastry dough product, modeling the release profile and evaluating the effectiveness of the active agent by extending the product shelf life.     

Effect of formulation on the capacity of l-asparaginase to minimize acrylamide formation in short dough biscuits

The influence of the matrix composition and structure on the capacity of asparaginase to reduce acrylamide formation in biscuits was studied. In particular, formulations differing for water (10 to 20% on total weight) and fat (0 to 15% on total weight) content, fat type (margarine, palm oil) and lipid phase distribution were considered. In the latter case, palm oil was substituted with a monoglyceride–palm oil–water gel (hydrogel). The results showed that high water contents, by favoring precursor mobility, promoted acrylamide formation as well as the enzyme capability of reducing the toxic molecule levels in the final product. On the contrary, the presence of fat significantly reduced acrylamide development and enzyme activity as compared with the fat free formulation. It can be hypothesized that the presence of fat would hamper the interaction between the precursors in the aqueous phase, leading to lower amounts of acrylamide. By substituting fat with hydrogel, the biscuit behaved as a fat free system, where acrylamide formation as well as its reduction by means of asparaginase activity was higher than in the fat-containing biscuits. It is likely that the inclusion of palm oil in the dough through the hydrogel modified the system morphology, thus not hampering the encounter among reactants and consequently favoring acrylamide formation.     

Evaluation of innovative technological approaches to replace palm fat with physically modified Swiss rapeseed oil in bakery products

Palm fat is often used in baked goods because of its relatively low cost, and its positive impact on texture and shelf life. Demand for alternatives has risen in recent years due to concerns about the ecological and social sustainability. This is a challenge for the bakery industry since palm fat possesses unique properties. In this study, unhydrogenated rapeseed oil was processed using novel physical technologies, such as wax crystallisation, stabilised foaming and Pickering emulsions, in order to simulate palm fat properties. Analysis showed that while the initial viscosity of the fat substitute products was low compared to palm fat, the fat replacement products behaved very similarly to palm fat in the baking experiments. The resulting biscuits baked with emulsified rapeseed oil and rapeseed oil complemented with wax crystals were judged to be suitable replacements for palm fat in terms of processability, as well as analytical and sensory assessment.     

The sensory attributes of cakes containing large numbers of low sugar raisins, as evaluated by consumers and a trained sensory panel

The sensory attributes of cakes, containing a greater number of low sugar raisins (LSR) than that normally used, were evaluated by two different groups of trained and untrained panellists. The purpose of this sensory evaluation was to find out whether such bakery products were more attractive to consumers than normal cakes and could be further promoted in the market. Cakes containing LSR and additional lemon peel scored more poorly than cakes containing only raisins, both in terms of taste and overall preference. Cakes containing only LSR had good sensory characteristics and could be considered as competitive products when compared with similar products already on the market. Young people found cakes with raisins tasty, but they did not consume them readily. The special advantages of these cakes are their natural ingredients, raisins with lower amount of sugars, good taste and high quality, all of which should be emphasized to make them attractive in the market.     

脂肪替代品在低脂肉制品中的研究进展

由于低脂肉制品可有效降低脂肪的摄入,且能预防高脂膳食所引起的各种慢性疾病,相关研究领域逐渐成为近年来的研究热点。本文基于国内外低脂肉制品的发展现状,从脂肪替代物、脂肪模拟物和复合型脂肪替代物三个方面综述了各自对低脂肉制品组成成分、组织结构、抗氧化性及感官评价等指标影响的最新研究进展,并就肉制品中脂肪替代物的发展方向进行了展望。      

The effect of hydrogel and silicone hydrogel contact lenses on the measurement of intraocular pressure with rebound tonometry

Purpose

To assess the accuracy of intraocular pressure (IOP) measurements using rebound tonometry over disposable hydrogel (etafilcon A) and silicone hydrogel (senofilcon A) contact lenses (CLs) of different powers.

Methods

The experimental group comprised 36 subjects (19 male, 17 female). IOP measurements were undertaken on the subject's right eyes in random order using a rebound tonometer (ICare). The CLs had powers of +2.00D, −2.00D and −6.00D. Six measurements were taken over each contact lens and also before and after the CLs had been worn.

Results

A good correlation was found between IOP measurements with and without CLs (all r ≥ 0.80; p < 0.05). Bland Altman plots did not show any significant trend in the difference in IOP readings with and without CLs as a function of IOP value. A two-way ANOVA revealed a significant effect of material and power (p < 0.01) but no interaction. All the comparisons between the measurements without CLs and with hydrogel CLs were significant (p < 0.01). The comparisons with silicone hydrogel CLs were not significant.

Conclusions

Rebound tonometry can be reliably performed over silicone hydrogel CLs. With hydrogel CLs, the measurements were lower than those without CLs. However, despite the fact that these differences were statistically significant, their clinical significance was minimal.     

Quantitative fit of a model for proving of bread dough and determination of dough properties

The early stages of bread dough proving were modeled following the diffusion theory and using a newtonian constitutive equation to account for dough rheology. The model was fitted, by constrained minimization of the sum of squared errors function, to experimental growth curves of common dough formulations. Values for the dough viscosity, a first order fermentation rate constant and the bubble size at the beginning of proving were chosen as the degrees of freedom in the fitting procedure. The viscosity value obtained for a plain dough formulation was 30 × 10⁶ Pa s, this value is in the range of viscosity values determined by Rouillé et al. (2005), for wheat dough through creep-recovery and lubricated squeezing flow tests. The results obtained were plotted as a function of dough formulation composition and the trends were observed and analyzed. The observed tendencies and correlations between dough properties and dough formulation follow the trends observed in experimental data reported in the literature for dough systems.     

Effects of lysosomal deposition on the friction coefficient of hydrogel contact lenses

When a contact lens is in contact with the eyelid and the cornea, tear proteins start to be accumulated on the lens and may subsequently undergo conformational changes. Protein adsorption or conformational changes on the lens may lead to discomfort, red eye, or even inflammatory reactions. Although measuring the friction coefficient of contact lens has been linked to comfort degree in vivo, there is not much research about the effects of tear protein deposition on the friction coefficient of the contact lens. Therefore, we investigated the friction coefficient of three distinct materials of contact lenses in two different lysosomal concentrations. We also studied lysozyme deposition on the lens without the influence of friction. The results demonstrated that although the amount of lysozyme deposition was high on all the materials we tested, it was not corresponded to higher friction coefficient. In addition, we investigated the effect of the contact lens care solution we developed on friction coefficient and lysozyme deposition of three different materials of contact lenses. The results showed that the care solution could reduce the increased friction coefficient caused by high lysosomal concentration. Therefore, we proposed a potential mechanism of why lysosomal deposition may result in high friction coefficient for certain types of hydrogel contact lenses.     

Factors influencing the prescribing of hydrogel contact lenses

Despite the current market popularity of silicone hydrogel contact lenses, conventional hydrogel lenses still represent a significant proportion of the overall contact lens market. Data gathered from annual UK contact lens fitting surveys over the past 13 years indicate that 64% of hydrogel lenses prescribed during this period were of low/medium water content (≤60% water). Whereas, in the past, practitioners would choose the water content of a hydrogel lens to meet specific clinical needs, this choice appears today to be largely governed by product availability.     

Mitigation of the processing contaminant acrylamide in bread by reducing asparagine in the bread dough

Over the past few years there has been an increasing awareness regarding acrylamide (AAM) content of various foods. Although there are several relevant articles on AAM mitigation in industrially prepared products, the literature regarding homemade preparations is rather scarce. The objective of this study is to mitigate the AAM formation in baked buns made with 1:1 sifted wheat/wholegrain flour through the depletion of asparagine (ASN) in the bread dough. Using a full-factorial design, the effect of four factors (yeast amount, fermentation time, fermentation temperature and yeast types) was tested. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for AAM and its main precursor, ASN, determination. The resulting ASN depletion in the dough (68–89%) is significantly affected by fermentation time and yeast type, while AAM mitigation levels in the baked buns are significantly influenced by yeast amount, fermentation time and yeast type. The mean concentrations for each combination range between 5 and 15 µg kg^–1.     

Consumer evaluation of bakery product flavour as affected by incorporating the prebiotic tagatose

This study evaluated whether incorporating tagatose, a monosaccharide with prebiotic properties, into bakery products affected their flavours. Cinnamon muffins, lemon cookies, and chocolate cakes were prepared; 1 or 2% tagatose was added to the experimental products while an equal amount of sucrose was added to the control products. Using triangle tests, untrained consumer panels (n=65–81) were unable to distinguish between the flavour of products with and without tagatose. In addition, the flavours of bakery products containing and not containing tagatose were liked similarly. Based on this data, bakery products may be formulated containing low levels of tagatose for its health benefits without altering the product's flavour.     

红糖色源物的探讨

红糖(又称为黑糖)的深红褐色源主要是甘蔗本身所具有的多种生理活性的多酚化合物与人体需要的微量元素,部分来自制糖过程各种化学变化形成的深色素物。本文对这些色素物试图进行剖析探讨,论述天然色素物的保健价值,讨论在制糖过程如何使美拉德反应既增加红糖的色、香风味的正面作用,又不会产生微量的不良产物-丙烯酰胺的负面作用。