Quality and Antioxidant Properties of Fried Chicken Breast Jerky Supplemented With Dolsan Leaf Mustard Powder (Brassica juncea)

돌산갓 분말이 첨가된 닭가슴살 육포 튀김의 품질적 특성

Abstract

The physicochemical properties, antioxidant activity, color value, sensory evaluation, and sinigrin content of chicken breast jerky supplemented with Dolsan leaf mustard powder (DLMP) were evaluated over a period of 120 days. The control groups contained no DLMP, and the product groups contained 0.04 g (S-1, S-3) and 0.3 g (S-2, S-4) of DLMP. These samples were stored at 25℃ and 60℃ and then compared. The pH changes decreased at 25℃ and 60℃ over the storage period, with S-1 maintaining the highest pH value over the course of the experiment. The acid and peroxide values increased at room temperature and 60℃ but were better controlled in the DLMP-containing groups. Overall, the antioxidant activity of these products decreased during storage; the most marked reduction was observed in the control group, and the greatest activity was retained in S-2 and S-4. Hardness and gumminess were higher in the S-2 and S-4 groups and thus correlated with increased DLMP concentration. Sinigrin content also increased with increasing DLMP concentration. Product color remained similar at days 0 and 120 but underwent daily fluctuations over the course of the 120-day storage period. Sensory evaluation scores for color, flavor, taste, texture, and overall acceptability were highest for the S-2 and S-4 groups stored at 25℃. This suggests that higher concentrations of DLMP were more effective at retaining good quality characteristics for fried chicken breast jerky. This was facilitated by its suppression, which decreased changes in textural and color properties while increasing the antioxidant activity of these products.

돌산갓 분말을 첨가한 닭가슴살 육포의 이화학적 특성, 항산화활성, 색도, 관능평가 및 sinigrin함량을 120일동안 저장하면서 측정하였다. 돌산갓 분말을 첨가하지 않은 대조군(Control)과 돌산갓 분말을 0.04 g(S-1, S-3)과 0.3 g(S-2, S-4)을 첨가한 제품군을 25℃과 60℃에 보관하면서 실험하였다. pH변화는 25℃과 60℃에서 저장 기간 동안 계속 감소하였고, S-1은 다른 제품들보다 높은 pH를 나타내고 있다. 산가와 과산화물가 25℃과 60℃에서 증가하였지만 대조군보다 억제되었다. 항산화활성은 총폴리페놀, 총플라보노이드, 전자공여능(EDA), ABTS radical 소거활성 및 Ferric reducing antioxidant power (FRAP) 항목으로 측정하였다. 전체적으로 항산화활성은 저장기간 동안 감소하였고 특히 대조군은 S-2, S-4 보다 낮은 활성을 나타냈다. 단단한 정도(Hardness)와 검성(gumminess)은 돌산갓 첨가량이 증가할수록 단단함과 검성은 S-2, S-4에서 높게 나타내고 있다. 또한 sinigrin 함량도 돌산갓 분말 첨가량이 증가할수록 높게 나타났다. 색도는 저장기간 동안 증가와 감소를 반복하면서 120일째에는 0일째와 비슷한 값을 나타냈다. 관능평가는 색, 향, 맛, 조직감, 전반적인 기호도로 25℃에 저장한 S-2와 S-4에서 높은 점수를 받았다. 돌산갓 분말 첨가량이 높은 제품일수록 저장기간 동안 산가와 과산화물가를 억제하였고, 물성과 색도는 감소와 항산화성 활성을 증가시킴으로써 닭가슴살 육포튀김의 품질향상에 효과적일 것으로 예상된다.

Introduction

Increasing longevity has increased people’s concern over their health, fostering greater interest in the use of, func- tional plant materials to prevent aging and maintain health [3,27]. Leaf mustard (Brassica juncea) belongs to the Cruciferae family and the stems and leaves of this plant are widely used as the main ingredient in leaf mustard kimchi or as a minor ingredient in many other kinds of kimchi. The seeds from this plant are also used to produce pungent spices be- cause of their hot taste and unique flavor [24]. Leaf mustard contains high levels of ascorbic acid, chlorophyll, and β-car- otene and has the highest antioxidant activity among leaf and stem vegetables [4,30].

The jerky is a traditional Korean food that is prepared by stirring and seasoning meat; this method has been used for storing food for a long time because the low moisture content of the foods prepared using this method allows foe their storage at room temperature for a long time. These jer- ky foods are widely used snacks, snacks, side dishes, and pyebaek [23]. Recently, the food industry has undergone a series of rapid developments which have changed the focus of these businesses. The current day consumer is looking for foods that are associated with numerous health benefits, extending well beyond simple nutritional or life main- tenance value. In order to satisfy these new consumer de- mands, many foods are being supplemented with functional ingredients.In the case of jerky manufacturing companies, many efforts have been made to develop technologies that can improve the quality of the product via the addition of various natural ingredients to meet the needs of consumer. Examples include beef jerky, green tea, rosemary, cloves, thyme, parsley powder [14], licorice, fennel seed, Cheon- gyang pepper extract [20], pine needle and mugwort juice[6], citron and plum extracts [16], and lotus leaf extract [23]. In addition, several studies have evaluated the effect of add- ing the following extracts paprika and plum extracts [19,22], onion shell extracts [8] and green tea and grapefruit seed extracts [10]. However, to our knowledge, one study has in- vestigated ingredient supplementation in chicken jerky [18]; in this study, the chicken jerky immersion solution was sup- plemented with various sugars. Importantly, compared to those on beef or pork jerky, there are very the few studies on ingredient supplementation in chicken jerky. Chicken is a high demand food by virtue of low fat and high un- saturated fatty acid and protein contents; these features make chicken a better choice for health conscious consumers. Chicken breast is known to be very poor in fat and rich in protein, amino acid, and essential fatty acid content; these features make chicken breast the cut of choice for health con- scious consumers However, due to its poor texture, consum- er preference remain low, thus, given the obvious benefits of chicken breast there isa need to develop a method to improve these considerations [18]. In this study, we inves- tigated the quality and antioxidant properties of fried chick- en breast jerky supplemented with different concentration of Dolsan leaf mustard powder (DLMP).

Materials and Methods

Materials and reagents

Dolsan leaf mustard (DLM) used in this experiment was purchased in January 2019 from the Dolsan leaf mustard Farming Association of Yeosu, Jeonnam Province. DLM was dried using a vacuum freeze dryer (FDU-8624, TRK, Japan), ground in a vacuum bag and then stored at -18℃ until use. The frying batter was purchased at local markets and had been prepared using soft flour, cornstarch, egg white pow- der, garlic powder, white pepper powder, red pepper pow- der, DLMP, and syrup. The chicken breast was thinly sliced under pressure and was used as it is. Sinigrin, Folin-Ciocal- teu’s phenol reagent, 1, 1-diphenyl-2-picrylhydrazyl (DPPH), 2, 2-azino-bis(3-ethyl-benzothizoline-6-sulfonic acid) (ABTS), sodium carbonate, gallic acid, 2, 4, 6-Tris(2-pyridyl)-s-triazine (TPTZ), iron (III) chloride hexahydrate, iron (II) sulfate hep- tahydrate (FeSO₄･H₂O), potassium persulfate, ascorbic acid, sodium chloride (NaCl), aluminum nitrate, potassium ace- tate, quercetin, methanol and ethanol were all purchased from Sigma-Aldrich (St. Louis, MO, USA).

pH

Fried chicken breast jerky was prepared using a frying batter supplemented with DLMP. DLMP wasground to a particle size of 5-10 mm using a high-speed mixer, and then, strained using sterile gauze. The pH of each sample was measured based on the mean value of 3 measurements on 10 ml of undiluted liquid DLMP using a pH meter (Orion 520A, Boston, USA).

Acid value (AV)

AV was determined using the method described by Kim et al. [11]. Briefly, 100 ml of ethanol: ethyl ether (1:2) mixture of 100 ml was added to 0.3 g of the sample and shaken well. Four drops of phenolphthalein solution were then add- ed and shaken for 5 minutes and the solution was then ti- trated with 0.1 N ethanolic potassium hydroxide. The end-point was determined based on a color change in the solution for 30 seconds.

AV (acid value) = 5.611 ⨉ (T-B) ⨉ F/W

T: Optimum consumption of 0.1 N ethanolic potassium hydroxide solution for this test (ml)

B: Optimum consumption of 0.1 N ethanolic potassium hydroxide solution in the blank test (ml)

F: Volume of the 0.1 N-KOH solution used for titration

W: Sample weight (g)

Peroxide value (POV)

POV was determined using the method described by Kim et al. [11]. Frist 30 ml of chloroform: acetic acid (2:3) mixture and 1 ml of saturated iodine potassium solution were added to 0.3 g of the sample, then the mixture was stirred lightly for 1 minute and incubated in the dark for 5 minutes. Then 30 ml of distilled water was added and the solution was titrated using 0.01 N sodium thiosulfate.The end-point was determined based on the loss of starch-associated coloration (colorless) the blank test was performed separately.

POV (meq/kg) = (A-B) ⨉ F ⨉ 10/S

A: Optimum consumption of 0.01 N sodium thiosulfate solution for this test (ml)

B: Optimum consumption of 0.01 N sodium thiosulfate solution of the blank test (ml)

F: Volume of 0.01 N sodium thiosulfate solution used for titration

S: Sample weight (g)

Total polyphenol content

The total polyphenol content of the fried chicken breast jerky supplemented with DLMP added was evaluated using the Folin-Ciocalteu’s phenol reagent in conjunction with col- orimetric method [29]. Folin-Ciocalteu’s phenol reagent (200 μl) and distilled water (2.6 ml) were added to the sample (200 μl), and the mixture was allowed to react for 6 minutes at room temperature. Then, 7% (w/v) Na₂CO₃ (2 ml) was added, and the mixture was left to react for 90 minutes. Absorbance was then measured using a microplate reader (Infinite F50, Männedorf, Switzerland) at 750 nm. Gallic acid was used to create a standard curve and the polyphenol con- tent was reported in mg gallic acid equivalents (GAE)/g.

Total flavonoid content

The total flavonoid content of the fried chicken breast jer- ky samples was evaluated using the Moreno method [17]. The sample (1 ml), 10% aluminum nitrate (0.1 ml) 1 M potas- sium acetate (0.1 ml), and 8% (v/v) ethanol (4.3 ml) were added sequentially, and the mixture was allowed to react for 40 minutes in the dark. Then the absorbance was meas- ured at 415 nm and a quercetin standard was generated, i.e., flavonoid content data are reported in mg quercetin equivalents (QE)/g.

Electron donating ability (EDA)

Electron donating ability (EDA), which is the radical scav- enging effect of 1, 1-diphenyl-2-picrylhydrazyl (DPPH), was used to evaluate the reducing power of the fried chicken breast jerky samples 0.5 mM DPPH (0.5 ml) was added to a test tube containing 1 ml of sample, 1 ml methanol, and 0.99 ml 100 mM sodium acetate buffer (pH 5.5), and then the mixture was agitated and left to react in the dark for 5 minutes. Radical concentration was then measured at 517 nm and was reported using the following equation [32]:

EDA (%) = (1 - absorbance of the solution with the sample added/absorbance of the solution without sample) ×100

2, 2-azino-bis(3-ethyl-benzothizoline-6-sulfonic acid) (ABTS) radical scavenging activity

ABTS radical scavenging activity was measured using the method described by Kriengsak et al. with minor mod- ifications [13]. Breiefly, equal volumes of 1.8 mM ABTS and 0.63 mM potassium persulfate were combined and left to react in the dark for 24 hr at 37℃, thereby facilitating the release of ABTS free radicals. This solution was then modi- fied so that the absorbance at 735 nm was 1.4±0.1 then, 5 ml of the ABTS solution containing ABTS radicals was add- ed to 0.1 ml of the sample, and allowed to react for 7 minutes. 735 nm was then measured and the reducing pow- er of the samples were calculated as folloes.

ABTS radical scavenging activity (%) = (1 - absorbance of the solution with the sample added/absorbance of the solution without sample) ×100

Ferric reducing antioxidant power (FRAP)

FRAP was evaluated using a slightly modified version of the procedure described by Benzie et al. [1]. Acetate buffer (30 mM; pH 3.6), 2, 4, 6-tripyridyls-triazine (TPTZ; 10 mM) dissolved in HCl (40 mM), and iron (III) chloride hexahy- drate (20 mM) in a 10:1:1(v:v:v) ratio. Then 150 μl of the sample and 2, 850 μl of this reaction mixture were reacted for 30 minutes; absorbance was measured at 593 nm and a standard curve was generated using FeSO₄·H₂O, FRAP content was quantified as mg FeSO₄ equivalents/g extract.

Sinigrin standard curve and high-performance liquid chromatography (HPLC) operating conditions

A sinigrin standard representing 125, 250, 500, and 1, 000 ppm was generated; each measurement was repeated three times and the mean value of these three measurements was used to generated the standard curve. This standard curve was then used to quantify the sinigrin content in each of the fried chicken breast jerky fried samples evaluated in this study. HPLC was hen performed using a Phenomenex Luna 5 um C18 column (4.6×250 mm) was used with a flow rate of 0.4 ml/min and an injection volume of 10 μl on a Shimadzu JP/LC-20Avp, fitted with a UV-VIS detector set at 228 nm.

Color analysis

The chromaticity of each sample was measured using a colorimeter (JZ-350, Kingwell, Shenzhen, China). Pulverized samples were evaluated for lightness (L, lightness), redness (a, redness), and yellowness (b, yellowness). All these analy- ses were completed using a standard whiteboard, L=97.07, a= -0.06, and b=0.21.

Texture analysis

The physical properties of the fried chicken breast jerky were evaluated by cutting the samples into 4x4 cm. The hardness and gumminess of each sample were measured three times on a rheometer (CR-500DX, Osaka, Japan), and expressed as an average value. The measurement conditions were set to a trigger load of 20 g, a test speed of 2 mm/s, and a load cell of 10,000 g.

Sensory evaluations

Ten trained panelists, all of whom were graduate students from the Chonnam National University, performed the sen- sory evaluations. The color, flavor, taste, texture and overall acceptability were evaluated using a 9-point scale (1 = very weak, 3=little weak, 5=moderate, 7 = little strong, 9 = very strong).

Statistical analysis

All tests and analyses were repeated at least three times. The results are expressed as the mean ± standard deviation (SD). One-way analysis of varance (ANOVA) and Duncan’s test were used to evaluate multiple comparisons on SPSS version 21.0 (SPSS Institute, Chicago, IL, USA). In all experi- ments, differences between values were considered signifi- cant at p<0.05.

Results and Discussion

pH, AV and POV during storage

Thinly pressed chicken breast jerky was battered using the batter described in Table 1 and fried at 160-180℃ for 380 seconds. Evaluations were performed every 30 days for 120 days upon storage 25℃ and 60℃. Fig. 1 shows the changes in pH, acid, and peroxide values for the fried chick- en breast jerky samples over the course of the storage period. The pH for these samples ranged between 5.17 and 5.95 on day 0, and the control group recorded the lowest pH value (5.03, 5.05) during the storage period. Chicken breast jerky samples stored at 60℃ showed a greater reduction in pH than those stored at 25℃. As the amount of DLMP increased, the pH of the fried chicken breast jerky decreased, and was similar to the pH profiles of chicken breast jerky supple- mented with Lycii fructus powder profile [33].

Table 1. Frying batter ingredients and Dolsan leaf mustard powder concentration for each group

Fig. 1. Changes in pH (A, B), acid value (C, D) and peroxide value (E, F) for fried chicken breast jerky over 120 days of storage at 25℃ and 60℃.

AV is used to index the degree of rancidity of fats and oils produced during the decompositin process that may alter the flavor profile of the food produce. AV acts as a direct indication of the free fatty acid content resulting in the concomitant deterioration of quality and is linked to the acceleration of automatic oxidation and lowering of the flame points [28]. The AV of fried chicken breast jerky stored at 25℃ and 60℃ gradually increased over the course of stor- age period. All of the DLMP supplemented products stored at 25℃ maintained an AV of one or less and all of the DLMP supplemented samples stored at 60℃ maintained an AV of two or less. Previous reports have shown that when oil comes into contact with air or impurities the oil oxidation rate increases [23]. Here we were able to show reduced ran- cidity in fried chicken breast jerky supplemented with DLMP, indicating-that DLMP may reduce oil oxidation dur- ing storage.

POV is an indirect indicator of oil oxidation and thus ran- cidity peroxide is the primary oxidative product formed dur- ing the oil oxidation process. If acidity continues to increase, peroxide would decomposed, resulting in reduced POV [9]. During the storage period, the control samples showed the highest peroxide value, and the peroxide values while the DLMP supplemented samples were less affected. The POV for fried chicken breast jerky with DLMP stored at 25℃ was 11.22 meq/kg, which was about 50% less than the POV for the control group. This suggests that the addition of DLMP to the batter inhibited the production of lipid peroxies [12]. The POV for fried foods cannot exceed 60meq/kg and none of the values exceeded this limit, suggesting that all of these products were safe for ingestion.

Changes in antioxidant activity during storage

Table 2 summarizes the results of our total polyphenol and flavonoid. Samples from the S-2 and S-4 groups demon- strated the highest total polyphenol and flavonoid content, and were shown to demonstrate the slowest reduction in these values over the evaluation period. Protein products or added phenolic compounds are reported to inhibit lipid oxidation via interactions with hydroperoxide and other re- actants produced during the early phases of fatty acid oxida- tion [7]. This finding was consistent with the results of this study that show that the total polyphenol content was higher in the DLMP supplemented samples and that the lipid per- oxide content was significantly lower in these samples when compared to that in the control. In the case of the fried chick- en breast jerky products stored at 25℃, the EDA level was significantly higher by 58.2-65.6% between day 0 and day 60 than that in the control, but this value began to rapidly decrease from day 90 to the end of our evaluation period stored at 60℃ exhibited a 50% reduction in EDA at day 120. ABTS radical scavenging activity was significantly higher in fried chicken breast jerky products supplemented with DLMP over the entire storage period, and S-2 and S-4 showed higher radical scavenging activity tan any of the other samples at day 0. In addition to radical scavenging ability, FRAP reducing power, an indirect measure of anti- oxidant activity was significantly higher in all the DLMP samples compared to that in the control group. Other studies have shown that jerky products supplemented with green tea extracts also exhibited reduced lipid peroxide production during storage, and that this was directly linked to the anti- oxidant activity of the green tea supplement [26], thereby demonstrating significant similarities with our study. Taken together these data suggest that fried chicken breast jerky would exhibit improved antioxidant properties and an ex- tended shelf life upon supplementation with an appropriate amount of DLMP.

Table 2. Changes in the antioxidant activities of fried chicken breast jerky over 120 days of storage

¹⁾mg GAE/100g

²⁾mg QE/100g

³⁾mg FeSO₄eq./100g

* Data represent the mean ± SD of experiments performed in triplicates. The different lower-case letters (superscript) in the same row (a-e) and column (A-D) indicate statistically significant difference by Duncan's multiple range test (p<0.05)

Changes in sinigrin and textural properties during storage

Table 3 summarizes our evaluations of the sinigrin con- tent and textural properties of the fried chicken brast jerky samples evaluated in this study. The control group did not contain any sinigrin, while all of the supplemented samples were positive for it. In addition, increasing DLMP content shown in S-2 and S-4 to correlate with higher sinigrin content. Further, we noted the following: longer the storage period and the higher the storage temperature, faster the decrease in the sinigrin content. In addition, sinigrin was very stable against heat, as it exhibited antibacterial activity even after heat treatment at 100℃ for 10-50 minutes and 12 1℃ for 10-30 minutes in heat stability for the extracts ex- tracted as they were and the water extracts pretreated with shaking [25].

Table 3. Changes in sinigrin content and textural properties of fried chicken breast jerky over 120 days of storage

¹⁾Not detected

* Data represent the mean ± SD of experiments performed in triplicates. The different lower-case letters (superscript) in the same row (a-d) and column (A-D) indicate statistically significant difference by Duncan's multiple range test (p<0.05)

Hardness refers to the transforming force required when cutting the jerky with the teeth and gumminess refers to the force required to break down the jerky using the tongue or teeth. The hardness and gumminess of fried chicken breast jerky supplemented with DLMP and stored at 25℃ were 6211.46-6985.73 g and 604.18-681.48 g, respectiely be- tween day 0 and day 60, the exception being the control group, that showed no significant difference in these values over time. Both hardness and gumminess are affected by changes in texture and can depend on various factors, in- cluding additives, rawness, drying method, frying method, and packaging method, among others [2, 5, 21, 31]. In gen- eral, Koreans tend to enjoy crispy fried foods, so fried foods with high hardness and elasticity are popular [18], given this samples S-2 and S-4 are expected to be more popular than the samples in the control group.

Changes in color value during storage

The results of the surface color evaluations are summar- ized in Fig. 2. The L-value, representing the brightness of the fried chicken breast jerky stored at 25℃ was 47.52 for the control group on day 0, and 44.01-57.62 for S-1, 2, 3, and 4 and was significantly reduced following 60 days of storage. The redness a-value was 12.46-16.24 and the yellow- ness b-value was 23.61-37.47, and was significantly de- creased over the storage period. In this study, this phenom- enon is thought to be the result of the browning of the pig- ment and free sugars, and amino acids found in DLMP dur- ing the frying process.

Fig. 2. Changes in color values of the fried chicken breast jerky over 120 days of storage at 25℃ and 60℃.

Changes in sensory evaluation during storage

Table 4 summarizes the results of the sensory evaluation of these fried chcken breast jerky products. Sensory evalua- tion showed high scores for samples S-2 and S-4 stored at 25℃, and included strong scores for color, flavor, taste, tex- ture, and overall acceptability, with all of these values being significantly higher than those of samples in the control group. Previous reports had suggested that there were no significant differences in the sensory evaluation results for jerky products supplemented with various spices including green tea, rosemary, cloves, thyme and parsley [15]. In view of the results of this study, it is hypothesized that the addi- tion 0.25% DLMP of chicken breast when preparing fried chicken breast jerky would positively influence the physio- logical activity of these products and increase their palat- ability and improve their storage capacity.

Table 4. Changes in the sensory evaluation of fried chicken breast jerky over 120 days of storage

* Data represent the mean ± SD of experiments performed in triplicates. The different lower-case letters (superscript) in the same row (a-e) and column (A-D) indicate statistically significant difference by Duncan's multiple range test (p<0.05)

 

In the physicochemical change, antioxidant activity, sini- grin content, color change, and sensory evaluation of fried chicken breast jerky products added with DLMP, the func- tionality increased as the amount of DLMP added increased. However, since studies on the separaion, purification, and identification of sinigrin and its derivatives, which are major components of DLMP are insufficient these studies will need to be further conducted in order to be used as functional food materials in the future.