Impact of Soaking in Salt Solutions after Blanching on Acrylamide Formation and Sensorial Quality of Potato Chips

Transcription

1 Impact of Soaking in Salt Solutions after Blanching on Acrylamide Formation and Sensorial Quality of Potato Chips Dorin Bakhtiary Department of Food Science and Technology, Payame Noor University (PNU), P.O. Box, Tehran, Iran ABSTRACT The main objective of this work was to study the effect of soaking blanched potato slices in different salt solutions on acrylamide formation and sensorial quality of fried potato. Prior to frying, potato slices (Agria variety, diameter: 7 mm, width: 1.5 mm) were blanched in hot water at 5Ċ for.5 min; these slices were considered as the control. Slices of the same dimensions were blanched as in the previous step, and soaked at 5Ċ in KCL, NaCL and CaCL solutions of /1 M for 5 min. Blanched and soaked slices were fried at 1Ċ for.5 min. The acrylamide content was determined by GC-ECD. The sensory quality of the potato chips was evaluated based on their crispness, aroma, flavor and overall acceptability by using 1- point hedonic scale, where 1= dislike extremely and 1= like extremely by 5 untrained panelists. Samples soaked in KCL, NaCL and CaCL solutions showed significant reduction in the formation of acrylamide by, and 55% respectively in comparison with control. CaCL showed more efficient in inhibiting acrylamide formation than KCL and NaCL. Results of sensory evaluation demonstrated that samples soaked in CaCL solution had significantly the lowest values of taste, odor and overall acceptability. While NaCL soaked samples had significantly (p< /5) the highest scores of overall acceptability. It was concluded that soaking of blanched potato slices in NaCL solution (/1 M) can be proposed as a reliable mitigation strategy to reduce acrylamide formation in fried potato with more acceptable sensory characteristics. KEYWORD Acrylamide, Potato chips, Blanching, Soaking, Salt solution, Sensory characteristic. INTRODUCTION Acrylamide has been classified as a probable carcinogen by the International Agency for Research on Cancer (IARC, 199). The detection of surprisingly high levels of acrylamide in fried or toasted potato and cereal products in April provoked extensive international research, which * dorin.bakhtiari@gmail.com Telephone Numbe : Fax. Numbe : progressed rapidly. These processed foodstuffs are widely consumed and shown to be extremely susceptible to acrylamide formation by Maillard reaction, mainly due to the abundant presence of the free amino acid asparagines and of reducing sugars (Stadler et al., ). Acrylamide formation in foods is influenced by several factors, including processing temperature, time, content and species of reducing sugars and amino acids, ph, moisture content and frying oils, indicating that acrylamide in foods can be decreased by changing processing technology (Ciesarova et al., ). Potato products, such as crisps and French fries, are among the major contributors to the acrylamide daily intake, especially for children and teens (Wilson et al., ). In the past years, many strategies aiming to reduce acrylamide formation in potato products have been proposed (Amrein et al., 7). The selection of potato varieties having a low concentration of free carbohydrates and the use of appropriate storage conditions are of pivotal importance (Biedermann et al., ). Many studies demonstrated that it is possible to define time-temperature processing conditions which guarantee low acrylamide concentration and the retention of sensorial properties in terms of color, flavor, and starch gelatinization (Pedreschi et al., ; Granda et al., ). In a recent paper, ferulic acid, hydrogen peroxide, ferulic acid combined with HO or Fe+, tea catechin,nahco and NaHSO were used to test the eliminating capacity for acrylamide under different temperatures and it was found that combination of ferulic acid with HO or Fe+ showed highest efficiency for eliminating acrylamide (Ou et al., ). Also, Levine and Smith (5) found that NaHCO, NHHCO, cysteine, sodium bisulfite and ascorbate could eliminate acrylamide; and citric acid, ferulic acid and NaCl decreased the amount of acrylamide produced. In addition, pre-treatment with the enzyme L-asparaginase is sufficient to reduce acrylamide content, since L-asparagine is considered to be one of the main precursors for the acrylamide formation in foods (Friedman, ). Since till now, wide researches were done about the useful ways to reduce the amount of acrylamide formation

2 in fried carbohydrate-rich foods especially potato chips (Matthaus et al, ; Knustsen et al, 9) But, the major challenge in frying of potatoes is to achieve a substantial reduction of acrylamide while keeping desirable product attributes such as color, flavor, texture, and taste (Pedreschi, 9). Because, for consumers the perceivable sensory attributes are the deciding factors in food acceptance (Pal et al., 1995). Therefore, the main objective of this work was to study the effect of soaking of blanched potato slices in different salt solutions on acrylamide formation and sensorial quality of fried potato. MATERIALS MATERIALS AND METHODS For this research 1 kg of potatoes (Solanum tuberosum L.), Agria variety, were purchased from Seed and Plant Improvement Institute of Iran and stored at 1 until preparing chips. For frying potatoes, refined, bleached and deodorized palm olein, was purchased from Behshahr factory. All chemicals and solvents used were purchased from Merck (Darmstadt, Germany). METHODS Preparation of potato chips. POTATO CHIP (SLICES) Potato tubers (Variety Agria) were washed and after peeling, slices (diameter: 7 mm, width: 1.5 mm) were prepared by using a mechanical slicer (Italimport SRL, Model 9915, China). BLANCHING TREATMENT Slices were rinsed immediately after cutting for 1 min in distilled water to eliminate some starch adhering to the surface prior to frying. Blanched samples were prepared by heating raw slices in l of hot water at 5Ċ for.5 min. Blanched slices were considered as the control. After blanching potato slices were cooled in ice water for 1 min. blanched slices were drained and fried at 1. SOAKING TREATMENT Slices of the same mentioned dimensions were blanched in distilled water at 5Ċ for.5 min. The blanched potato slices were drained and divided into three portions and were soaked at 5Ċ in KCL, NaCL and CaCL solutions of /1 M for 5 min. The soaked slices were drained and fried at 1. FRYING CONDITION 1 g of each treatment were fried in an electric deep fryer with a capacity of Lit of oil at 1 for /5 min in palm olein. After frying, the samples were dried to remove excess oil. DETERMINATION OF ACRYLAMIDE Method of measuring acrylamide by Gas Chromatography which is equipped with an electron capture detector (ECD) is based on extraction of the acrylamide from defatted sample with sodium chloride and derivatization of acrylamide with bromine and then tracking it by an electron capture detector (ECD). MANNER OF EXTRACTION The samples were prepared for acrylamide analysis using a procedure described by Lehotay and Mastovska (). In the first stage, 5/ g of the homogeneous sample were mixed with 5 ng/g of meta acrylamide as an internal standard, 5 ml of hexane solution and distilled water and acetonitrile in the equal ratio by vortex mixer for 15 minutes. Then, 5 g of sodium sulfate anhydrous and sodium chloride were added to it. The mixture was centrifuged at 5 rpm for 5 minutes and after using ultrasonic for minutes, the acetonitrile layer was separated completely. MANNER OF DERIVATIZATION The collected acetonitrile layer was brominated based on a procedure described by Tareke and Rydber (). For this aim, potassium bromide, hydrobromic acid and saturated bromine water were used. Obtained solution was kept in the refrigerator at for a day. Then, the excess of bromine became colorless by adding some drops of sodium thiosulfate solution and this solution was extracted twice with 5 ml of ethyl acetate. The obtained organic phase was dried with 1 g of sodium sulfate and transferred in to rotary vacuum evaporator. Then the solution was concentrated under the nitrogen gas till a volume of 5 µl. Finally, 1 µl from each of prepared samples was injected into the capillary column ( m /5 mm /5 µm) of GC/ECD. Four standard solutions of acrylamide were prepared with volumes of 1, 15,, 5 ml and were extracted and brominated on the basis of procedure described for the samples. The calibration curve was generated by injecting 1 µl from each of acrylamide standards into the GC/ECD and acrylamide concentration formed in the samples was determined by using this curve ( Figure1.) Table 1. GC-ECD Device Parameters Area from GC-ECD GC-ECD Parameters Column temperature - Ċ Injection temperature 5 Ċ Detector temperature Ċ Injection volume 1 µl y= 11 x R² = ppb Fig.1. GC-ECD Calibration Curve

3 SENSORY EVALUATION The sensory quality of the examined potato chips was evaluated based on their crispness, aroma, flavor and overall acceptability by using 1-point hedonic scale, where 1= dislike extremely and 1= like extremely by 5 untrained panelists. STATISTICAL ANALYSIS The experiments were carried out in the completely randomized design (CRD) in triplicates. The average was compared with each other by Duncan method. Analysis of variance (ANOVA) and comparison of averages was done by SPSS1. software. RESULTS AND DISCUSSION RESULTS OF TESTING ACRYLAMIDE As shown in figure, Samples soaked in KCL, NaCL and CaCL solutions for 5 min showed significant (p<.5) reduction in the formation of acrylamide by, and 55% respectively in comparison with control. CaCL showed more efficient in inhibiting acrylamide formation than KCL and NaCL. Moreover, the formation of acrylamide appeared to be significantly lower in NaCL soaked slices compared to samples for KCL. Similar results were reported recently (Mestdagh et al., ; Pedreschi et al., 9). The acrylamide inhibiting mechanism for KCL, NaCL and CaCL may be due to its complexation with amines and some intermediates of the Maillard reaction products as reported before (Delgado-Andrade et al., ; O Brien and Morrissey, 1997). Recently, evidence was found that cations such as Ca+ or Mg+ would change the reaction path from the Maillard reaction toward dehydration of glucose (Gokmen and Senyuva, 7).Also it has been reported that Na+ or Ca+ could interact with asparagine to prevent the formation of acrylamide (Park et al., 5; Lindsay and Jang, 5; Gokmen and Senyuva, 7). On the other hand, the addition of NaCl, CaCl or KCL might also change the oil uptake (Bunger et al., ; Rimac-Brncic et al., ; Pedreschi et al., 7). This could therefore be an additional factor, possibly influencing the formation of acrylamide in fried foodstuffs. Acrylamide ppb Control 1 RESULTS OF SENCORY EVALUATION Results of this study showed that significant (p</5) differences occurred in the sensory characteristics of examined potato chips. Samples soaked in NaCL solution had significantly (p</5) the highest scores of taste, odor and overall acceptability while CaCL soaked samples had the lowest. Moreover, control was more acceptable for panelists in taste, odor and overall acceptability than the KCL soaked samples (Figures, and 5). These results confirm previous findings (Varela et al., 7; Pedreschi et al., 7). Potassium chloride and Calcium chloride can cause a bitter aftertaste (Varela et al., 7). Consequently, these pre-treatments may also cause unwanted sensorial defects. score of taste Fig.. Average of taste in control and blanched potato strips dipped in KCL, NaCL and CaCL solutions (/1 M). Control corresponds to potato strips blanched in hot water at 5Ċ for.5 min and numbers 1, and score of odor Control 1 Control 1 Fig.. Acrylamide content of control and blanched potato strips dipped in KCL, NaCL and CaCL solutions (/1 M). Control corresponds to potato strips blanched in hot water at 5Ċ for.5 min and numbers 1, and Fig.. Average of odor in control and blanched potato strips dipped in KCL, NaCL and CaCL solutions (/1 M). Control corresponds to potato strips blanched in hot water at 5Ċ for.5 min and numbers 1, and

4 score of overall acceptability 1 Control 1 respectively in comparison with blanched potato slices as a control. Although that CaCL showed more efficient in inhibiting acrylamide formation than KCL and NaCL but potato slices soaked in CaCL solution had the weakest scores of taste, odor and overall acceptability while NaCL soaked samples had the highest values of overall acceptability. According to this fact that for consumers, the perceivable sensory attributes are the deciding factors in food acceptance, it was concluded that soaking of blanched potato slices in NaCL solution (/1 M) can be proposed as a reliable mitigation strategy to reduce acrylamide formation in fried potato with more acceptable sensory characteristics for consumers. Fig.5. Average of overall acceptability in control and blanched potato strips dipped in KCL, NaCL and CaCL solutions (/1 M). Control corresponds to potato strips blanched in hot water at 5Ċ for.5 min and numbers 1, and indicate the blanched potato strips soaked for 5 min at 5Ċ in KCL, NaCL Soaking of potato strips in salt solutionss previous to frying could reduce significantly the oil absorption and increased texture parameters in the fried potatoes (Bunger et al., ). According to the obtained results of this study soaking of blanched potato slices in KCL, NaCL and CaCL solutions improve significantly the crispness of texture in fried potatoes in comparison with control. And samples soaked in CaCL solution had significantly (p</5) the highest scores of crispness. Moreover, NaCL soaked samples appeared to be more acceptablee for panellists in crispness than the samples for KCL (Figure ). Similar results were reported recently (Varela et al., 7; Pedreschi et al., 7). 1 score of crispness Control 1 Fig.. Average of crispness in control and blanched potato strips dipped in KCL, NaCL and CaCL solutions (/1 M). Control corresponds to potato strips blanched in hot water at 5Ċ for.5 min and numbers 1, and CONCLUSION Results of current investigation showed that soaking of blanched potato slices at 5Ċ in KCL, NaCL and CaCL solutions for 5 min before frying reduced dramatically acrylamide formation of potato chips by, and 55% REFERENCES [1] Amrein, T.M., Andres, L.., Escher, F., Amado, R, 7. Occurrence of acrylamide in selected foods and mitigation options. Food Addit. Contam, : 1-5. [] Biedermann-Brem, S., Noti, A., Grob, K., Imhof, D., Bazzocco, D., Pfefferle, A,. How much reducing sugar may potatoes contain to avoid excessive acrylamide formation during roasting and baking. Eur. Food Res. Technol, 17: 9-7. [] Bunger, A., P. Moyano and V. Rioseco,. NaCl soaking treatment for improving the quality of french-fried [] potatoes. Food Res. Int., : [5] Ciesarova, Z., E. Kiss and E. Kolek,. Study of factors affecting acrylamide levels in model systems. Czech J. Food Sci., : [] Delgado-Andrade, C., I. Seiquer, R. Nieto and M.P. Navarro,. Effects of heated glucose-lysine and glucose-methionine model-systems on mineral solubility. Food Chem., 7: 9-7. [7] Friedman, M,. Chemistry, biochemistry and safety of acrylamide. Journal of Agricultural and Food Chemistry, 51: 5-5. [] Granda, C., Moreira, R.G.. Tichy, S.E,. Reduction of Acrylamide Formation inpotato Chips by Low-temperature Vacuum Frying. Journal of Food Science, 9 (): [9] Gokmen, V. and H.Z. Senyuva, 7. Acrylamide formation is prevented by divalent cations during the Maillard reaction. Food Chem., 1: 19-. [1] IARC, (199). Acrylamide.. Monographs on the evaluation of carcinogenic risks to humans: Some industrial chemicals. : 9-. [11] Knutsen, S.H., Dimitrijevic, S., Molteberg, E.L., Segtnan, V.H., Kaabera, L., Wicklund, T, 9. The influence of variety, agronomical factors and storage on the potential for acrylamide formation in potatoes grown in Norway, LWT-Food Science and Technology, : [1] Lehotay, J., Mastovska, K,. Rapid sample preparation method for LC-MS/MS or GC-MS analysis of acrylamide in various food matrices. Journal of Agricultural and Food Chemistry, 5: [1] Levine, R.A. and R.E. Smith, 5. Sources of variability of acrylamide levels in a cracker model. J. Agric. Food Chem., 5: 1-1. [1] Lindsay, R.C. and S. Jang, 5. Chemical intervention strategies for substantial suppression of acrylamide

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