Effects of dough formula and baking conditions on acrylamide and hydroxymethylfurfural formation in cookies

The effects of dough formula and baking conditions on the formations of acrylamide and hydroxymethylfurfural (HMF) were studied in a cookie model system. Increasing the sugar concentration in the dough formula increased acrylamide formation during baking at 205 °C for 11 min. The effect of sugar on acrylamide formation was more pronounced for glucose than for sucrose, expectedly. Addition of citric acid into dough formula comprising sucrose increased the susceptibility of acrylamide formation, while it decreased acrylamide formation in the dough formula comprising glucose. Decreasing the pH of dough formula increased the tendency to surface browning and the formation of hydroxymethylfurfural in cookies during baking. The results suggest that a cookie with acceptable texture and colour, but having less than 150 ng/g of acrylamide, can be manufactured by lowering the baking temperature and avoiding reducing sugars in the recipe.     

Effect of salt and sucrose addition on the formation of the Amadori compound from methionine and glucose at 40 °C

Four model solutions with the Maillard precursors methionine and glucose were reacted at 40 °C for up to 15 days. The solutions had a high or low precursor concentration leading to either high or medium water activity (0.96; 0.86). The water activity of the two other solutions was reduced by adding either salt or sucrose. Glucose, methionine and the Amadori compound (Fru–Met) were quantified after 1, 2, 6, 10 and 15 days. The results show that high salt and sucrose levels had a much more pronounced influence on glucose consumption and Fru–Met formation than differences in water activity. Glucose degradation and Fru–Met formation was favoured by high sucrose levels and inhibited by high NaCl levels.     

Effect of leavening agents and sugars on the formation of hydroxymethylfurfural in cookies during baking

The effects of recipe compositions in terms of leavening agent (ammonium and sodium bicarbonates) and sugars (sucrose and glucose), and baking conditions (temperature and time) on HMF formation in cookies were studied. Five recipes were prepared by varying the types of leavening agent and sugar. The cookies were baked at different temperatures (180, 200, 210 and 220 °C) for different time (10, 15, 20 and 25 min) to monitor physical and chemical changes in cookie composition in terms of water activity, pH, surface browning, sugar decomposition, and hydroxymethylfurfural (HMF) formation. Decreasing moisture to a level under a water activity of 0.4 appeared as the critical point in baking where the rate of HMF formation drastically increased after this point. After this stage, sucrose decomposed very rapidly if ammonium bicarbonate was used as the leavening agent at temperatures greater than 200 °C. Replacing ammonium bicarbonate with sodium bicarbonate maintained pH of cookies ranging between 9.0 and 10.0 during baking, which limited the decomposition of sucrose.     

Evaluation of the non-enzymatic browning in thermally processed apple juice by front-face fluorescence spectroscopy

Fresh apple juice was heated at 95 °C for 30 and 60 min, and then stored for 6 days for obtaining different extent of non-enzymatic browning. Front-face fluorescence excitation–emission-matrix (EEM) with excitation at 355 and 400 nm and emission ranges of 385–600, and 430–600 nm was used to measure the juice samples. The sign test pointed out an enhanced sensitivity of EEM compared to commonly used browning indicators, such as non-enzymatic browning index (NEBI), color readings in L^∗a^∗b^∗ space, and the concentration of 5-hydroxymethylfurfural (HMF). Using the fluorescence data, the correctness of classifications of fresh juice, heated juice, and stored juice were >85%. Multivariate analyses were applied to study the relations of fluorescence emission spectra and common indicators. For predicting NEBI, b^∗, and HMF, the correlation coefficients were >0.80. Resulting, the spectroscopic analyses of fluorescent neoformed products such as HMF provide a feasible approach to monitor non-enzymatic browning of juice.     

Physical and nutritional evaluation of wheat cookies supplemented with pulse flours of different particle sizes

With the aim to develop functionally and nutritionally improved cookies, the influence of the total or partial replacement of wheat flour by pulses flours on the quality characteristics of cookies was analysed. Blends containing 25, 50, 75 and 100 g/100 g of navy bean, pinto bean, green lentil and commercial yellow pea flours were prepared. Green lentil, navy and pinto bean flours were used at two degrees of milling (fine and coarse). The incorporation of pulse flours significantly affected the physical and chemical parameters of the cookies. Incorporation of fine flours remarkably increased cookies’ hardness and decreased spread while coarse flours marginally reduced both parameters. The greatest impact on the physical characteristics was observed with the incorporation of green lentil flour, where cookies made with coarse flour were of unacceptable structure and were sticky to handle. Cookies baked with pulse flours were higher in protein level and showed increased antioxidant activity compared to the control. Overall analysis indicated that cookies with acceptable physical characteristics and improved nutritional profile could be produced with partial or complete replacement of the wheat flour.     

Effect of antibrowning agents on browning and intermediate formation in the glucose-glutamic acid model

In this study, the inhibitory effects of antibrowning agents on browning and the formation of intermediates such as 3-deoxyglucosone (3-DG) and hydroxymethylfurfural (HMF) were evaluated with a glucose-glutamic acid model for soybean paste. The initial antibrowning capacity was measured in the following order: pentasodium tripolyphosphate < citric acid and oxalic acid < cysteine and glutathione < sodium sulfite. Our data showed that antibrowning agents, such as pentasodium tripolyphosphate, citric acid, and oxalic acid, were maintained antibrowning capacities during storage at both 4 and 30 °C, respectively. However, both cysteine and glutathione was reduced with storage time, especially in the air. A marked effect of nitrogen treatment was noted for 3 of the antibrowning agents after storage in air at 30 °C in the following order: sodium sulfite < cysteine < glutathione. The formation ratio of 3-DG and HMF was higher after storage at 30 °C than at 4 °C. These compounds were produced most abundantly in the presence of sodium sulfite, and the yields were not related significantly to the degree of browning. Citric acid and oxalic acid were identified as the most effective in inhibitors of browning and intermediates, even during storage in air at 30 °C.     

Effects of short-term anoxia treatment on browning of fresh-cut Chinese water chestnut in relation to antioxidant activity

The effects of short-term anoxia pre-treatment on browning of fresh-cut Chinese water chestnut (CWC), stored at 4 °C, in relation to antioxidant activity were investigated. CWC slices were exposed to pure N₂ for 4 h and then stored at 4 °C for 18 d. Anoxia significantly inhibited browning of CWC slices during storage, accompanied by lower contents of malondialdehyde, H₂O₂, and lipoxygenase activity. Furthermore, anoxia induced the activities of superoxide dismutase and ascorbate peroxidase, which could benefit scavenging reactive oxygen species and alleviating lipid peroxidation. In addition, better maintenance of reducing power and free-radical-scavenging activities against α,α-diphenyl-β-picrylhydrazy (DPPH), superoxide anions and hydroxyl was observed in N₂-treated CWC slices, with higher phenolic compounds and ascorbic acid contents. Collectively, these finds suggest that N₂ pre-treatment enhanced enzymatic and non-enzymatic antioxidant activity in CWC slices, and thereby contributed to alleviating lipid peroxidation and maintenance of storage quality.     

Redox-potential and browning of tomato paste in aluminium tubes during storage at different temperatures

The influence of temperature and applied lacquer on aluminium (Al) tubes on physico-chemical changes of tomato paste during storage was studied. Packaging and storage conditions have a considerable influence on both the oxidative changes in the product and corrosion behaviour of the Al tubes. The greatest changes during storage were the ascorbic acid and hydroxymethylfurfural contents; the compounds known to possess certain oxido-reduction power. The consequence of oxidation-reduction reactions taking place during storage was the establishment of particular redox values: the lower the reducing power of the compounds present, the higher the rH value obtained.

---

Braunwerden und Redoxpotential des Tomatenkonzentrates bei verschiedenen Lagerungstemperaturen

Zusammenfassung Es wurden der Einfluß der Temperatur und der Alu-Verpackung auf physikalisch-chemische Änderungen des Tomatenkonzentrates während der Lagerung untersucht. Dabei wurde festgestellt, daß die Verpackung und die Lagerungsbedingungen auf die oxydativen Veränderungen des Tomatenkonzentrates und der Korrosionsprozeß in der Alu-Verpackung einen großen Einfluß haben. Die größte Änderungen während der Lagerung wurde im Gehalt an Askorbinsäure und Hydroxymethylfurfural festgestellt. Die genannten Verbindungen haben gewisse Redox-Eigenschaften. Die Redox-Reaktion während der Lagerung hat Einfluß auf die Veränderung des Redox-Potentials, und zwar ist dieses um so höher, je niedriger die Reduktionskraft der anwesenden Verbindungen ist.

     

Study of hydroxymethylfurfural and furfural formation in cakes during baking in different ovens,using a validated multiple-stage extraction-based analytical method

A procedure for extraction of hydroxymethylfurfural (HMF) and furfural from cakes was validated. Higher yield was achieved by multiple step extraction with water/methanol (70/30) and clarification with Carrez I and II reagents. Oven type and baking time strongly influenced HMF, moisture and volatile profile of model cakes, whereas furfural content was not significantly affected. No correlation was found between these parameters. Baking time influenced moisture and HMF formation in cakes from traditional and microwave ovens but not in steam oven cakes. Significant moisture decrease and HMF increase (3.63, 9.32, and 41.9 mg kg⁻¹ dw at 20, 40 and 60 min, respectively) were observed during traditional baking. Cakes baked by microwave also presented a significant increase of HMF (up to 16.84 mg kg⁻¹ dw at 2.5 min). Steam oven cakes possessed the highest moisture content and no significant differences in HMF and furfural. This oven is likely to form low HMF and furfural, maintaining cake moisture and aroma compounds.     

防止贮存期柿口干提取液氧化褐变的研究

柿叶提取液加入不同浓度的D－Vc、蜂蜜、β－环糊精、植酸、明胶、壳聚糖等药剂，于37℃恒温贮存40天后取样分析，结果表明：各试验组药剂对防止柿叶提取液中维生素C和单宁的氧化褐变有显著的效果。     

Effect of Temperature and Initial Moisture Content on the Chemical Stability and Color Change of Various Forms of Vitamin C

Vitamin C is a widely used food ingredient, and its stability is both important and sensitive to environmental conditions. To monitor chemical and color stability, samples were prepared with varying water contents (0–50 mol water/mol solid) and stored at temperatures (22–60°C) for up to eight weeks. Three common methods (UV/Vis spectroscopy, high performance liquid chromatography, and 2,6-dichloroindophenol titration) were used to monitor chemical stability. Color changes were documented using Hunter colorimeter analysis. Both temperature and moisture content had a significant effect on chemical stability. Browning occurred faster than chemical degradation, and kinetic models were developed for both chemical degradation and color change.     

Influence of various parameters on the browning of potassium sorbate in the presence of amines

Potassium sorbate can undergo oxidation to form carbonyl moieties and cause browning. This investigation studied the fate of the compounds produced by auto-oxidation of potassium sorbate and measured the browning in the presence of amines. Experimental plans in which four factors were combined (temperature, oxygen, amine and light) led to the observation that the interaction between oxygen and high temperature (75°C) favoured browning, independently of the presence of amine. At 4°C, the amine seemed to cause a decrease in the proportion of carbonyl-containing compounds which would appear to participate in carbonylamine reactions. At 75°C, the amine forms adducts with the potassium sorbate. In parallel, high temperature favours auto-oxidation reactions that produce carbonyls. GC/MS and NMR analysis of the reaction products of potassium sorbate/amine mixtures led to the identification of cyclic products.     

荔枝保藏中的褐变研究进展

本文根据荔枝果实的结构与生理特点，综述了荔枝保藏中果皮褐变的原因，着重从水分、多酚氧化酶及花色素苷三方面进行了评述，并阐述了褐变产生的机制及控制的途径。     

Effect of raffinose on sucrose recrystallization and textural changes in soft cookies

ABSTRACT:  Sucrose recrystallization and the release of moisture that occurs as molecules of sugar are incorporated into a growing crystal lattice have been hypothesized as the cause of firming in soft cookies over time. Raffinose, a trisaccharide and known sucrose crystallization inhibitor, was tested as a means to inhibit or slow this process. Texture changes in the cookies were quantified using peak force measurements obtained by employing a puncture test. Sucrose recrystallization was successfully suppressed by the addition of 5% raffinose (w/w), as demonstrated by quantitative results obtained using powder x-ray diffraction and the degree of crystallization correlated with texture. Cookies with added raffinose were found to be significantly softer in texture, as well as having significantly decreased quantities of recrystallized sucrose. The hypothesis that sucrose recrystallization is responsible in part for the firming of cookies was shown to be logical.     

Water sorption isotherms of fresh and partially osmotic dehydrated pumpkin parenchyma and seeds at several temperatures

Experiments were conducted to determine the equilibrium moisture content of pumpkin (cv Cucurbita Pepo L.) at different temperatures (278.1 K, 298.1 K and 318.1 K) and relative humidities (8–91%). Fresh and partially osmotically dehydrated (using sucrose solutions) samples of pumpkin parenchyma were employed. The desorption isotherm of pumpkin seeds at 298.1 K was determined as well and was found to be similar to other sorption isotherms of other seeds with similar fat and protein compositions. No significant dependence of the equilibrium experimental data on the temperature or osmotic pre-treatment was found. Several common mathematical models were used to fit the experimental data. For the parenchyma tissue, statistical analysis proved that those of Halsey, Oswin, Chirife and GAB were the best, while for the seeds, the Henderson, GAB and Peleg models are preferable.     

Effect of flour type on Maillard reaction and acrylamide formation during toasting of bread crisp model systems and mitigation strategies

Maillard reaction along with caramelisation are the main chemical reactions occurring in bakery products. They are referred to as non enzymatic browning. In this work, the effect of flour type (wheat, rye and whole-wheat flours) and process conditions were investigated by using a bread crisp model system made up of flour, water and yeast. The bread was toasted at different temperature for different times. In a second set of experiments several additives (glycine, 0.1% on flour; asparaginase, 2000 U kg⁻¹ of flour and an antioxidant extract from green tea) were added to the basic formulations in order to test their ability in reducing the formation of potentially harmful Maillard reaction compounds such as HMF and acrylamide. Browning development and water content along with antioxidant activity were also monitored.Rye model systems produced more HMF and acrylamide at all temperature tested, while wholewheat systems produced less HMF, but more acrylamide than wheat one. The addition of glycine was effective in reducing acrylamide formation, and it increased browning development, antioxidant activity and HMF formation. Asparaginase reduced acrylamide formation up to 88% and had no effect on browning development and antioxidant activity. The addition of exogenous antioxidant compounds from green tea did not produce clear effect on acrylamide formation, thus it was not useful as mitigation strategy in bakery products, likely because of the low fat content.     

Identification of the miRNAs and their target genes involved in fresh-cut potato browning inhibition by nitrogen

Browning decreases the quality and shortens the shelf life of fresh-cut potato, causing enormous economic losses. This study indicated that nitrogen treatment could inhibit this browning process. However, whether microRNAs (miRNAs) are involved in inhibiting the fresh-cut potato browning by nitrogen remains unclear. Therefore, nine small RNA libraries were constructed and performed high-throughput sequencing using fresh-cut potatoes from control and nitrogen-treated for 1 h groups at 25 °C to identify the miRNAs and their target genes involved in fresh-cut potato browning inhibition by nitrogen. The results revealed that four common differentially expressed miRNAs (DEmiRNAs) were identified as associated with browning. The correlation analysis indicated that fresh-cut potato browning was closely related to the expression of DEmiRNAs and their potential target genes. The miR172d targeting APETALA2/ethylene response factor and phospholipase D, miR482e targeting ATPase GET3-like, and PC-3p-17015_391 targeting stachyose synthase are vital in the nitrogen inhibited fresh-cut potato browning by regulating the ethylene signalling pathway, membrane lipid metabolic process, ATPase activity, and carbohydrate metabolic process. This study provides new insights into fresh-cut potato browning inhibition and helps to improve the quality of fresh-cut potato using nitrogen.     

Comparison of the viscosity of trehalose and sucrose solutions at various temperatures: Effect of guar gum addition

The viscosity of trehalose and sucrose solutions was measured and compared as well as the effect of adding guar gum. Viscosity measurements of trehalose and sucrose solutions were performed in the range 20-45 g/100 g; 0.1 g guar gum/100 g was added in mixed systems. Viscosity of trehalose or sucrose solutions was measured at 20, 27 and 34 °C. Trehalose solutions had always a higher viscosity than sucrose, with the biggest difference (p < 0.001) in the range 30-45 g/100 g. Addition of guar gum revealed a synergistic effect with both disaccharides, particularly for trehalose. Viscosity dependence on temperature was also analyzed by calculating activation energies for all systems studied.     

Effect of malvidin-3-monoglucoside on the browning of monomeric and dimeric flavanols

 The behaviour of (+)-catechin (cat), (–)-epicatechin (epi) and the procyanidin dimers B2 [epi-(4→8)-epi] and B3 [cat-(4→8)-cat], alone and in the presence of malvidin-3-monoglucoside, was studied in hydro-alcoholic solutions at pH 3.2 maintained at 32  °C for 120 days. Browning was observed both in the presence and absence of the anthocyanin, except in the solution containing only cat. The formation of pigments showing maximum absorption in the visible region of 440–460 nm was detected. The majority of these new pigments did not require the anthocyanin for their formation, but rather were derived directly from the flavanol. Nevertheless, some specific pigments showing similar spectra appeared in each of the solutions containing both a flavanol and the anthocyanin, and their production was attributed to a condensation process between the two latter compounds. The cat units showed a greater tendency to condense with the anthocyanin, while the epi units were more sensitive to chemical oxidation. The formation of pigments which showed maximum absorbance in the visible region around 530–545 nm, resulting from the condensation between the flavanol and the anthocyanin mediated by acetaldehyde, was also detected. As no acetaldehyde was added to the solutions, its presence was attributed to the oxidation of ethanol coupled to autoxidation of the catechol rings of the flavanols. Received: 29 December 1997 / Revised version: 23 March 1998     

The role of polyphenol oxidase and peroxidase in the browning of water caltrop pericarp during heat treatment

The mechanism of browning involving enzymatic browning was investigated in the pericarp of water caltrop, an Asian vegetable popular for its taste and medicinal properties. Polyphenol oxidase (PPO) and peroxidase (POD) activities were determined in pericarp at various times and temperatures. Water caltrop consisted of 44.22% moisture content, 37.23% crude fibre, and 2.63% crude protein. PPO and POD activities dropped from 62 and 38 units/g sample, respectively, as water temperature was increased from 30 to 80 °C. Optimum pH and temperature for PPO activity was at pH 5.0, 25–45 °C, and POD activity peaked at 60 °C. High PPO and POD activities at 40–50 °C resulted in degradation of phenolic compounds, which led to increased aggregation of browning pigments and discolouration (lower L-values) of the pericarp. Enzymatic browning was determined as the major factor in the browning discolouration of heat-treated water caltrop pericarp.