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Paper No. CSBE17142

Performance of Palm Olein During Repeated Frying of Tortilla Chips

Andrea García-Pérez Abel Cerón-García César Ozuna María Elena Sosa-Morales

Departamento de Alimentos, División de Ciencias de la Vida, Campus Irapuato-Salamanca, Universidad de Guanajuato. Carretera Irapuato-Silao km 9, Ex Hacienda El Copal. Irapuato, Guanajuato, MEXICO 36500. msosa@ugto.mx

Written for presentation at the CSBE/SCGAB 2017 Annual Conference Canada Inns Polo Park, Winnipeg, MB

6-10 August 2017 ABSTRACT Fried products are very appreciated by the consumers, such as tortilla chips, which are very popular in North America. The oil employed for the frying of these products is used in repeated occasions, affecting the quality of the final product. In order to improve the performance of the oils/fats, antioxidants are added. Synthetic antioxidants (for example, butylated hydroxytoluene, BHT) are being replaced by natural antioxidants; the replacement should be assuring that the performance will be the similar than the synthetic compound. The aim of this work was to evaluate the performance of palm olein with different antioxidants during the repeated frying of tortilla chips. The tested antioxidants were BHT at 200 ppm (synthetic) and ascorbyl-palmitate (AP) at 100 ppm (natural) and their blend. Tortilla dough included 2% sesame. This was sheeted, cut, baked and fried. Batches of 80 g of tortillas were deep-fat fried at 190°C for 2 min to produce the chips. Chemical indices, such as free fatty acids (FFA) and peroxide value (PV), as well as physical parameters (color) was evaluated. After 20 batches, the values for olein+BHT were PV=29.6 meq/kg, and FFA=0.19%; for olein+AP were PV=,13.3 meq/kg and FFA=0.27%; olein+BHT+AP, PV=11.81 meq/kg and FFA=0.29%. Due to PV was higher than 20 meq/kg, the performance of olein with BHT as antioxidant is poor, only 1 day of use. The use of natural antioxidant AP improved the performed of palm olein.

Keywords: palm olein; tortilla chips; frying.

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INTRODUCTION Tortilla chips is a fried product very popular in North America (Morales-Pérez & Velez-Ruiz, 2010), which are corn dough-based foods, baked and fried. In the United States is one of the most popular snack (Kawas & Moreira, 2001). Deep fat frying is a common process at the industrial, catering and domestic scales for coking food. Fried foods are very appreciated by consumers and the food industry, the main reason for this is that frying is a fast process and different final products can be prepared, besides gives to food unique organoleptic characteristics taste, flavor, color, texture and palatability (Saguy & Dana, 2003). The frying process is complex and involves many factors, for the processing environment itself, characteristics of food and the type of oil used. Quality of deep-frying food is inseparably of the quality of the used deep-frying oils (Weisshaar, 2014).

The frying process may be considered as a dehydration process, when the water and other materials out to the food into the surrounding oil and the oil take a place into the food. Also a heat and mass transfer between the oil and the food occur, these phenomena and the temperature which is mostly between 150 and 190 °C (Gertz, 2014) can promote deteriorative chemical process as oxidation, polymerization and hydrolysis of mainly unsaturated but also saturated fatty acids (Matthaus, 2007). Lipid oxidation is one of the major problem during frying process and in storage of fried products (Guo, et al., 2016). Palm olein is used extensively in food industry. It has a competitive price and is more stable at high temperatures than other edible oils and desirable physico-chemical properties, as texture, melting point and content of a relativity high saturated fatty acids (Siddique, 2010)

Autoxidation of lipids is carried out in a free radical chain mechanism. This chain involves three steps: initiation, propagation and termination, being cyclical. The primary oxidation products are formed by the reaction of radical lipids (R∙) with atmospheric oxygen, called peroxy radical (ROO∙), which react into secondary oxidation products as aldehydes, ketones, lactones, alcohols, and acids. These compounds are often related to undesirable odors and flavors, described as rancidity (Saad, et al., 2007). On the other hand, the hydrolysis is caused by evaporation of water of food into the oil, breaking the bond of triacylglycerols, leading diglycerides, monoglycerides, free fatty acids and glycerol (Saguy & Dana, 2003) increasing the oil acidity.

In order to retard, reduce or prevent oxidative deterioration, antioxidants are added to oil. Antioxidants may be classified as primary and secondary. Primary antioxidant, also called of type I, are chain-braking antioxidants they can act delay or inhibit the initiation step or interrupt the propagation step of autoxidation, some of them are Butylated Hydroxyanisole (BHA), Butylated Hydroxytoluene (BHT), Tertiary-butylhydroquinone (TBHQ) and gallates. Secondary antioxidants, are also called of class II, they act as chelators for prooxidant or catalyst metal ions, provide H to primary antioxidants, decompose hydroperoxide to nonradical species, or act as oxygen scavengers. The secondary antioxidants often enhance the antioxidant activity of primary antioxidants (Wanasundara & Shahidi, 2005).

The aim of this study was evaluated the performance of palm olein added with BHT 200 ppm; Ascorbyl-palmitate (AP) 100 ppm, with synergist effect (Masson et al., 2002); and their blend to improve the stability of palm olein in frying process to tortilla chips. Different analytical methods are used to monitoring the changes which decreased the quality of frying oil (Navas et al., 2007).

MATERIALS AND METHODS

Materials. Palm olein added with two different antioxidants, Butylated Hydroxy Toluene (BHT) 200 ppm, ascorbyl-palmitate (AP) 100 ppm and their blend, were supplied by Aarhus Karlshamn, Mexico.

Tortillas chips were made with corn commercial flour and sesame seed 2% w/w, using for 1 kg of flour, 20 g of sesame blended and 1.83 mL of water, all the ingredients were mixed until obtain a

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homogeneous dough; tortillas were made in a metal press, then were cut in circles of 4 cm of diameter and finally baked in a griddle for 60 s. Tortillas chips baked and frying are show in figure 1. They were storage at fridge until their use.

Figure1. Tortilla chips elaborated with 2% of sesame seed.

Repeated frying procedure. In a commercial electric deep fat fryer (T-fal) with 3 L of capacity, fresh palm olein was heated until 190°C, then tortilla chips were fried for 120 s. There was a total of 25 batches. One batch was 80 g of tortilla. These conditions were modified from Abdulkarim et al. (2007). The procedure was repeated for each antioxidant.

Samples. Samples of oil and tortilla chips, were collected at beginning and from the batches 10, 15, 20 and 25 to each cycle of frying.

Oil samples analysis. Samples of oil were analyzed for measure the oxidation and hydrolysis behavior and physical parameters.

Peroxide Value. (PV) The peroxide value is based on the quantitation of the primary oxidation products, mainly hydroperoxides, from unsaturated fatty acids. It was determinate according to the Mexican Standard, NMX-F-154-1987. 1 g of used palm olein was added with 1 g of potassium iodide (KI) and 20 mL of acetic acid and chloroform (mixture 2:3) and were shaken until dissolve, the mix was heated in a water bath for 1 minute and added 0.5 mL of a solution of KI 5%. After a minute, 30 mL of hot water (18-20 °C) and 2 mL of starch 2% indicator solution were added. The mix was colored brown, then added sodium thiosulphate (Na2S2O3) until distinguish visual end-point when the mix turn to a white color or light yellow. Each test was done in duplicate. The results are expressed according the next equation

(1) 𝐼𝑃 #$%&'

=)*+,-,./∗1∗233

'

p-Anisidine Value. (AnV) The p-anisidine value, measures the secondary oxidation products as 2-alkenals and another aldehydes. It was carried according the manual of the Food Lab Touch Junior (CDR Foodlab., Florence, Italy), an instrument for rapid methods. The results were expressed as p-anisidine value according to the reference AOCS (Cd 18-90).

Free Fatty Acids (FFA)The free fatty acids were carried according to the standard method AOAC (1984). 3 g of used palm olein were taken in a flask, 30 mL of isopropyl alcohol were added to it followed by 2 drops of phenolphthalein. Sodium hydroxide was added until colored. Each test was done in duplicate. The results were expressed as % palmitic acid, according the next equation

(2) 𝐴𝐺𝐿 = )*+.7∗1∗3.9:;'

𝑥100.

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Color. The color test was carried in ColorFlex EZ 45/0 spectrophotometer (Hunter Associates Lab., Inc. Reston, VA. Unites States) at 25°C. The results were expressed as CIE L*a*b* scale. Each test was done in triplicate.

RESULTS AND DISCUSSION

Oxidative deterioration The PV is one of the most widely used test, and the Mexican Standard stablish as maximum limit for this parameter 20 meq/kg, after to reach this value the oil must be discarded. The initial value for the olein with AP, BHT and AP+BHT were respectively 0, 1.95 and 2.7 meq/kg. Palm olein with BHT after 20 batches has the highest value 29.612 meq/kg. PV decrease after 25 batches; this is a normal behavior for PV, as reported by Rady & Madkour (1995), due to after a maximum level, new secondary compounds are formed. Palm olein with AP+BHT had lower peroxide values than oleins containing individual antioxidants.

As oil deterioration continues, the peroxides method is useful just in the first step of oxidation, does not give information about the next step. The appropriated method to evaluate secondary oxidation is p-anisidine reaction Guo et al., 2016). Three different samples of fresh palm olein have the same AnV of 1.2, the AnV was increasing through the time in all the samples, the final values after 25 batches were 4.3 for AP, 4.4 for BHT and 4,5 for the blended. Guo et al, (2016) reported 1.7 as initial value for palm olein and palm olein+BHA and values after 5h of frying potatoes at 180°C of 15.4 y 8.6 respectively. Table 1 shows the values for oxidative deterioration parameters

Hydrolytic deterioration For Free Fatty Acids (FFA), the maximum limit is 3% as Mexican Standars establishes. FFA are reported as a percentage of the majority fraction of fatty acid, in palm olein is palmitic acid. Palm olein+BHT has lower values than other antioxidants and olein+BHT+AP has higher. The initial FFA values were 0.01% for olein+BHT and 0.08% for olein+AP and olein+BHT+AP; after 25 batches has values of 0.19%, 0.27% an 0.29% respectively, Figure 2 shows the initial values and after batches 10,15 20 and 25.

Table 1. Oxidative deterioration values for palm olein after different batches during repeated frying of tortilla chips with 2% sesame.

Characteristic

Batch

Antioxidant BHT AP BHT+AP

Peroxide value

(meq/kg)

0 1.95 0 2.7

10 13.532±1.3 10.238±1.47 5.390±1.52

15 15.066±1.78 11.920±0.59 8.076±0.63

20 29.612±1.21 13.378±0.64 11.815±1.37

25 12.491±1.39 11.278±0.36 12.160±0.98

p-anisidine value

AnV

0 1.2 1.2 1.2

10 2.7 3.7 2.1

20 3.0 3.7 2.9

25 4.4 4.3 4.5

*PV shows an average of three replicates and their standard deviation. AnV not has replicates.

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Figure 2. Free fatty acids for palm olein after different batches during repeated frying of tortilla chips

with 2% sesame.

Color. Color is an important physical characteristic of an oil. It was measured to evaluated the darkening in oil through frying time, table 2 shows values for parameters L* (lightness), a* (redness) and b* (yellowness) for each olein, after batches 10,15, 20 and 25. As well know, in frying process the color of oil becomes darker, and increases the intensity of red and yellow colors (Rady & Madkour, 1995). Thus, a* and b* parameters increase and L* value, which measured lightness, decreases.

Table 2. Hunter parameters of color of palm olein after different batches during repeated frying of tortilla chips with 2% sesame.

Parameter

Batch

Antioxidant

BHT AP BHT/AP

L*

10 72.5166±0.45 67.12±1.40 69.56±3.51

15 67.8233±5.19 62.2866±6.98 70.1466±1.59

20 70.7966±0.74 68.5166±3.20 59.4766±2.13

25 71.2633±1.53 59.5666±4.49 63.0366±4.13

a*

10 -4.46±0.18 -3.84±0.28 -4.3±0.67

15 -3.44±1.04 -2.4866±1.68 -4.1266±0.20

20 -3.8966±0.12 -3.86±0.61 -1.7633±0.49

25 -4.02±0.16 -1.6466±1.12 -2.21±0.83

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b*

10 49.7166±1.5 46.6866±1.16 46.1166±1.02

15 50.0533±1.67 47.7266±1.27 46.8433±0.99

20 46.5066±5.62 47.35±0.72 48.2533±0.70

25 49.9066±0.81 49.0966±0.99 48.5333±0.34

*Values show an average of three replicates and their standard deviation.

CONCLUSION. The best performance of palm olein was observed when a blend of antioxidants 200 ppm BHT + 100 pm ascorbyl palmitate were used for the repeated frying of tortilla chips, made by corn flour and 2% of sesame seed. When 200 ppm of BHT was employed as antioxidant, the peroxide values exceeded the permitted value for this index. More antioxidants should be studied in order to extend the performance of palm olein when is used for repeated frying of tortilla chips, as these chips are a valuable product in the market.

Acknowledgements. Authors thank to EDUCAFIN, CONACYT and Presidency of Campus Irapuato-Salamanca for financial support.

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