| 1. |
- Aalaei, Kataneh, et al.
(författare)
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Application of a dye-binding method for the determination of available lysine in skim milk powders.
- 2016
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Ingår i: Food Chemistry. - : Elsevier BV. - 1873-7072 .- 0308-8146. ; 196, s. 815-820
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Tidskriftsartikel (refereegranskat)abstract
- A dye-binding method using Acid Orange 12 was investigated regarding its suitability for the quantification of available lysine, as a means of monitoring the Maillard reaction in skim milk powders. The method was evaluated by analyzing a wide range of milk powders produced by three different drying methods and stored under various conditions. A pilot-scale freeze-dryer, spray-dryer and drum-dryer were used to produce skim milk powders and the samples were stored at two temperatures (20°C and 30°C) and two relative humidities (33% and 52%) under strictly controlled conditions. Moreover to validate the method, two protein isolates; bovine serum albumin and casein were investigated for their available lysine content. The results demonstrate the suitability of this method for measuring the available lysine in skim milk powders with good precision and high reproducibility. The relative standard deviations obtained from the 125 freeze-dried powders were 1.8%, and those from the 100 drum-dried samples were all 1.9%. The highest variation was found for the spray-dried powders, which showed relative standard deviations between 0.9% and 6.7%.
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| 2. |
- Aalaei, Kataneh, et al.
(författare)
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Chemical methods and techniques to monitor early Maillard reaction in milk products; A review
- 2019
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Ingår i: Critical Reviews in Food Science and Nutrition. - : Informa UK Limited. - 1040-8398 .- 1549-7852. ; 59:12, s. 1829-1839
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Forskningsöversikt (refereegranskat)abstract
- Maillard reaction is an extensively studied, yet unresolved chemical reaction that occurs as a result of application of the heat and during the storage of foods. The formation of advanced glycation end products (AGEs) has been the focus of several investigations recently. These molecules which are formed at the advanced stage of the Maillard reaction, are suspected to be involved in autoimmune diseases in humans. Therefore, understanding to which extent this reaction occurs in foods, is of vital significance. Because of their composition, milk products are ideal media for this reaction, especially when application of heat and prolonged storage are considered. Thus, in this work several chemical approaches to monitor this reaction in an early stage are reviewed. This is mostly done regarding available lysine blockage which takes place in the very beginning of the reaction. The most popular methods and their applications to various products are reviewed. The methods including their modifications are described in detail and their findings are discussed. The present paper provides an insight into the history of the most frequently-used methods and provides an overview on the indicators of the Maillard reaction in the early stage with its focus on milk products and especially milk powders.
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| 3. |
- Aalaei, Kataneh, et al.
(författare)
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Early and advanced stages of Maillard reaction in infant formulas : Analysis of available lysine and carboxymethyl-lysine
- 2019
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 14:7
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Tidskriftsartikel (refereegranskat)abstract
- Although the literature on the Maillard reaction in infant formulas is extensive, most studies have focused on model systems, and in only a few cases on real food systems. Therefore, the objective of the present study was to determine the status of the Maillard reaction, both the early and advanced phases, in a variety of commercial infant formulas available on the Swedish market. Ten powder and liquid milk-based infant formulas from three manufacturers were selected to determine available lysine and CML contents, the two established indicators of the reaction. The products were also characterized with respect to protein content, carbohydrates composition, water content and water activity. In order to be able to compare the impact of different processing steps applied on powder and liquid formulas, the solid formulas contained similar ingredients as their corresponding liquid ones. Our findings showed that powder and liquid formulas contained similar available lysine concentrations regardless of the manufacturer, showing 27.14–36.57% decrease in the available lysine, compared to the reference skim milk powder in this study. The CML concentrations were in a broad range of 68.77–507.99 mg/kg protein. In the case of one manufacturer, liquid infant formulas had significantly higher CML content, compared to the powder products (p < 0.05). The results from this study are a step taken towards better understanding of the extent of the Maillard reaction in real complex systems of infant formulas.
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| 4. |
- Aalaei, Kataneh, et al.
(författare)
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Kinetics of available lysine in stored commercial skim milk powder at moderate temperatures
- 2018
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Ingår i: International Journal of Food Science and Technology. - : Wiley. - 0950-5423. ; 53:9, s. 2159-2165
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Tidskriftsartikel (refereegranskat)abstract
- Kinetics of lysine blockage, as an early step of the Maillard reaction, was investigated in commercial skim milk powder to understand the extent of the reaction, specifically after packages are opened and during the subsequent storage. Samples were stored at six conditions including three temperatures (30, 32.5 and 35 °C) and two relative humidities (43% and 52%) for 30 days, the period in which the product is recommended to be consumed after opening. The reaction rate was determined using a dye-binding method. Based on our findings, decrease in available lysine follows first-order reaction kinetics model. Small changes in temperature (2.5 °C) caused significant increase in the reaction rate constants. Relative humidity affected temperature dependency of the reaction, and activation energies were estimated to be 142.5-170.8 kJ mol-1. This study aims to increase the awareness of the significance of storage quality in relation to the nutritional status of the products.
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| 5. |
- Aalaei, Kataneh, et al.
(författare)
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Storage stability of freeze-dried, spray-dried and drum-dried skim milk powders evaluated by available lysine
- 2016
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Ingår i: LWT - Food Science and Technology. - : Elsevier BV. - 0023-6438. ; 73, s. 675-682
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Tidskriftsartikel (refereegranskat)abstract
- Formation of Maillard products and the influencing factors, which are of crucial importance for both manufacturers and consumers, are still not fully understood. Thus in this study available lysine was used as a marker to monitor the extent of Maillard reactions in freeze-dried, spray-dried and drum-dried skim milk powders during 200 days of storage at highly controlled atmospheres. Storage variables included two temperatures (20 °C, 30 °C) and two relative humidities (33%, 52%). The available lysine in five replicates was quantified at pre-determined intervals by a dye-binding method using Acid-orange 12, validated in our previous work. Findings of this study show that temperature and relative humidity during storage have a profound influence on the rate of available lysine loss. Choice of the drying technology as the other investigated variable also had a significant impact. The drying process least affected the available lysine content in freeze-dried powders, followed by spray-dried and drum-dried powders. Storage at 52% relative humidity and 30 °C for 200 days led to a 39.2–45.9% decrease in the available lysine content, regardless of the drying of skim milk powder, while the powders stored at 33% relative humidity and 20 °C did not show a significant loss during the same period of time.
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| 6. |
- Aalaei, Kataneh, et al.
(författare)
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The Impact of Different Drying Techniques and Controlled Storage on the Development of Advanced Glycation End Products in Skim Milk Powders Using Isotope Dilution ESI-LC-MS/MS
- 2017
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Ingår i: Food and Bioprocess Technology. - : Springer Science and Business Media LLC. - 1935-5130 .- 1935-5149. ; 10:9, s. 1704-1714
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Tidskriftsartikel (refereegranskat)abstract
- The impact of different drying techniques and storage conditions on the formation of carboxymethyl lysine (CML) as an advanced glycation end product (AGE) was investigated in various pilot-scale produced skim milk powders (SMP). CML, an indicator of advanced stages of the Maillard reaction, was analyzed by isotope dilution ESI-LC-MS/MS after drying and at intervals during storage for 200 days. The aim of this study is to increase the awareness that the development of AGEs can be hindered by controlled storage, which is mostly neglected at the domestic level by the consumers. Pilot-scale freeze-dryer, spray-dryer, and drum-dryer were utilized for manufacturing SMPs. The storage was designed in such a way that it simulated how an average consumer keeps the dried products at home, specifically after opening the packages and how the products may be exposed to unfavorable conditions. To do so, four storage conditions including two temperatures (20 °C, 30 °C) and two relative humidities RH (33%, 52%) were studied and CML formation was monitored using LC-MS/MS. Our results show that the spray-dried samples developed two times higher CML after 200 days, compared to the freeze-dried samples, and this value was 1.6 times for the drum-dried samples. Storage at 52% RH developed 9.8–10 times more CML in the samples, in comparison with 33% RH, at the same storage temperature (P < 0.05). Our findings demonstrate that AGEs, molecules suspected to be involved in risks factors for auto-immune diseases, may be formed during storage of SMPs after opening the packages by the consumers.
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| 7. |
- Ahrné, Lilia, et al.
(författare)
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Improvement of texture by modifying processing conditions
- 2003
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Ingår i: Acta Hortic.. - : International Society for Horticultural Science. - 9789066059764 ; 604, s. 277-277
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Konferensbidrag (refereegranskat)abstract
- Fruit and vegetable processors, faced with the challenge of gaining and maintaining a healthy position in the competitive fruit and vegetable sector, are optimising traditional processes towards product quality. Using frozen potatoes as a case study, the aim of this study was to evaluate the potential of improving the texture of potatoes by modifying the processing conditions. The texture of processed frozen potatoes is the result of the integral effect of the unit operations applied through the production chain. Production of frozen potatoes includes a blanching, a freezing, thawing/cooking step before being served. In this study, blanching temperatures from 70 to 97 °C up to 10 minutes were tested and combined with freezing by two freezing methods, impingement and air-blast freezing. The texture was measured after cooking of frozen potatoes in boiling water. Besides texture, water holding capacity, microstructural evaluation and pectinmethylesterase (PME) activity were determined. Blanching of potatoes prior to freezing can both improve water holding capacity and texture of potatoes, but this effect depends on the freezing rate and blanching temperature. Potatoes frozen with fastest freezing method are firmer and hold more water than the ones frozen by air-blast freezing. Blanching at 70 °C can lead to potatoes that after cooking retain a firmer texture, compared with blanching at 90 °C. The duration of the blanching treatment has also an important effect on texture changes. The studies of PME activity showed a good correlation between texture and PME for blanching at 90 °C, but for blanching at 70°C and longer times, the development of texture does not seem to be solely related to PME activity. Microstructural studies showed that the differences in texture are due to differences in the degree of starch gelatinisation and integrity of the cellular structure.
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| 8. |
- Alessandrini, Laura, et al.
(författare)
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Effect of steam cooking on the residual enzymatic activity of potatoes cv. Agria
- 2011
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Ingår i: Journal of the Science of Food and Agriculture. - : Wiley. - 1097-0010 .- 0022-5142. ; 91:12, s. 2140-2145
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The aim of this work was to study the influence of steam cooking on pectin methylesterase (PME) and endogenous alpha- and beta-amylase activities in different tissues (cortex and pith) of raw and heat-treated potatoes cv. Agria. Three different cooking temperatures were chosen (55, 70 and 85 degrees C). For each cooking trial, time-temperature profiles were recorded and the degree of cooking was expressed in terms of cooking factor. RESULTS: Steam cooking contributed to significantly activate PME at 55 degrees C and to reduce its activity at the final processing temperature (85 degrees C), with the highest amount in the cortex (0.3745 +/- 0.0007 mu mol galacturonic acid (GA) g(-1) fresh weight (FW) min(-1)) compared with the pith (0.2617 +/- 0.0012 mu mol GA g(-1) FW min(-1)). The presence of heat-labile and heat-stable isoforms of PME in the considered potato tissues was also assumed. Heat treatment by steam resulted in a significant decrease in endogenous alpha- and beta-amylase activities in both tissues compared with the raw potato, though without complete deactivation. Starch-degrading enzymes were also found to be differently distributed in the raw tuber. CONCLUSION: Steam cooking affected in different ways the assessed residual enzymatic activity in the considered tissues of potatoes cv. Agria. Further research is needed to confirm the results obtained. (C) 2011 Society of Chemical Industry
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| 9. |
- Alklint, Charlotte, et al.
(författare)
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Accelerated storage and isothermal microcalorimetry as methods of predicting carrot juice shelf-life
- 2005
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Ingår i: Journal of the Science of Food and Agriculture. - : Wiley. - 1097-0010 .- 0022-5142. ; 85:2, s. 281-285
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of predicting the shelf-life of pasteurized carrot juice by isothermal microcalorimetry or change in pH was investigated and compared with traditional plate count results. A small increase in thermal power (2 muW), maximal increase of and acceleration of thermal power all gave rapid, well-correlated results for the shelf-life, as did pH, during accelerated storage. The effect of accelerated storage (17degreesC) on the microbial flora of pasteurized carrot juice was also compared with the flora from storage at 8degreesC, and it was found that accelerated storage is feasible for the rapid evaluation of shelf-life, but that the microbial flora in the spoilt juice will be different. (C) 2004 Society of Chemical Industry.
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| 10. |
- Alklint, Charlotte, et al.
(författare)
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Effects of modified atmosphere on shelf-life of carrot juice
- 2004
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Ingår i: Food Control. - 0956-7135. ; 15:2, s. 131-137
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Tidskriftsartikel (refereegranskat)abstract
- The effects of de-aeration and modification of the headspace atmosphere on carrot juice shelf-life were investigated. The shelf-life was defined by microbial growth, determined by isothermal calorimetry and plate counts. Compared with storage under air, de-aeration of carrot juice by helium or nitrogen bubbling, followed by flush packaging had no effects on shelf-life. Similar treatment with carbon dioxide, giving a carbonated drink, prolonged the shelf-life by up to 250%. This effect could not be explained by the change in pH to 5.6, since the shelf-life was not prolonged by the addition of hydrochloric acid until pH <4.5. Both the concentrations of H+ and of dissolved CO2 were correlated to the shelf-life of fresh carrot juice; higher concentrations giving shorter shelf-lives. The concentration of dissolved CO2 was also linearly correlated to the peak thermal power. (C) 2003 Elsevier Ltd. All rights reserved.
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