Effects of Rice Batter on Oil Uptake and Sensory Quality of Coated Fried Okra FRED F

JFS S: Sensory and Nutritive Qualities of Food

Effects of Rice Batter on Oil Uptake and Sensory Quality of Coated Fried Okra FRED F. SHIH, KAREN L. BETT-GARBER, KIM W. DAIGLE, AND DAPHNE INGRAM

ABSTRACT: Okra was coated and deep-fat fried with batters of flour sources including rice flour, a mixture of rice flour and small amounts of pregelatinized rice flour (PGRF), and, as a control, traditional wheat flour. The addition of PGRF, up to 8%, enhanced batter viscosity and the coating properties of the rice batter. Oil uptake of the fried batter decreased with the addition of up to 5% PGRF. Rice flour fried batters, with and without PGRF, were found to absorb substantially lower oil, by as much as 51%, compared with the wheat batter. The fried okra coated with the rice batter containing 5% PGRF, when evaluated for sensory properties on appearance and surface attributes, was found to be superior or equal to those with the wheat batter and rice batter without PGRF. Particularly, its golden brown color is considered more desirable than the lighter yellow color of the other 2 entities. Similarly, most of its 1st-bite and after-chew properties were slightly better and were in the normal range of commercially available products. Specifically, its distinctive crispiness is considered a positive attribute, whereas its slightly higher tooth packing properties, while remaining in the range of commercial products, may be noticeable to some consumers. Keywords: rice batter, fried okra, oil uptake, sensory quality

Introduction en drumsticks and fish sticks, relatively fewer studies are reported ice ingredients are popular for use in foods because they are on coated fried foods of vegetable sources (Makinson and others Rknown to be nutritious, gluten free, and hypoallergenic (Helm 1987). Particularly lacking is information on the evaluation of oil and Burks 1996; Yokoyama 2004). They are particularly desirable for uptake and sensory quality of fried vegetables. use in infant foods or in products for people with celiac disease (glu- In this report, we coated and fried okra with batter formulations ten intolerance) (Zain and Ahamad 1985; Gallagher and others of various flour sources, including rice flour, a mixture of rice flour 2004). They also have the unique functional property of low oil and pregelatinized rice flour (PGRF), and traditional wheat flour. We uptake during frying, which is essential for the development of low then investigated and evaluated the oil uptake and sensory prop- oil food products (Mohamed and others 1998; Shih and Daigle erties of fried products. 1999). Crispy coatings are a critical part of the acceptance of fried foods. Materials and Methods However, they normally absorb great amounts of oil during frying, which has become a concern because excessive oil consumption is Materials known to contribute to obesity and many other health problems Long grain rice flour (RL) and PGRF (Remyflo R500P) were pro- (Robert 1989). Theories on oil retention in fried foods have not been vided by Riceland (Stuttgart, Ark., U.S.A.) and A&B Ingredients fully established. Some studies suggested that, during frying, oil (Fairfield, N.J., U.S.A.), respectively. Wheat flour (Pillsbury All Pur- simply replaces moisture that is evaporated or lost (Gamble and pose Flour, The Pillsbury Co., Minneapolis, Minn., U.S.A.), okra, and others 1987; Rice and Gamble 1989). Among other factors, food frying oil (LouAna vegetable oil, Ventura Foods, Opelousas, La., components and their interactions appear to play an important role U.S.A.) were purchased from a local market. All other chemicals in determining the oil-moisture relationship during the frying of used were of reagent grade and safe for human consumption. food and, in turn, the oil uptake. Essentially, mechanisms that en- able the formation of oil-barrier films or increase the water-holding Preparation of batter slurry capacity may reduce oil uptake (Duxbury 1989; Balasubramaniam A solid mixture was prepared containing common ingredients and others 1997; Lin and Mei 2000). Thus, gums, proteins, and (1.0% sodium bicarbonate, 3.0% sodium chloride, and 0.72% sodi- modified starches, including methylcellulose (Pinthus and others um pyrophosphate) and 95.28% flour (wheat flour, rice flour, or a 1993), proteins (Mohamed and others 1998), and rice flour (Mo- mixture of rice flour and various amounts of PGRF). Batter slurries hamed and others 1998; Shih and Daigle 1999), have been used as of constant solid content were prepared by adding 50 g of the sol- S: Sensory & Nutritive Qualities of Food additives in the preparation of reduced-oil food products. id mixture to 60 g deionized water. The batter slurry was mixed for Batters have been used commercially in coating a wide variety of 5 min at room temperature, equilibrated for another 5 min, and fried foods. However, while information is readily available in the then analyzed for viscosity. literature on coated and uncoated animal foods, such as fried chick- Batter viscosity was determined using an RVA-3D analyzer (Foss Food Technology Co., Eden Prairie, Minn., U.S.A.). Batter slurry (28 MS 20040231 Submitted4/15/04, Revised 6/30/04, Accepted 9/7/04. The au- g) was placed in the sample cup and the viscosity in centipoise or thors are with USDA-Southern Regional Research Center, 1100 Robert E. Rapid Visco Unit (RVU) was read after spinning, 1st at 960 rpm for Lee Blvd., New Orleans, LA 70124. Direct inquiries to author Shih (E-mail: 10 s and then at 160 rpm for the remaining time, a total of 4 min at [email protected]). 30 °C. Batter slurries of comparable viscosity were also prepared by

S18 JOURNAL OF FOOD SCIENCE—Vol. 70, Nr. 1, 2005 © 2005 Institute of Food Technologists Published on Web 12/22/2004 Further reproduction without permission is prohibited Rice batter coated fried okra . . .

Table 1—Sensory appearance and texture attributes Appearance Color description: the actual color name describing the batter, such as from yellow to brown, and so forth 0 = yellow to 15 = brown Evenness of coating: the evenness of distribution of the batter over the product 0 = uneven/blotchy to 15 = even Surface consistency/texture: the amount of irregularity, protrusions, grains, or bumps, which can be seen on the surface of the product (batter) 0 = smooth to 15 = rough Surface shine: amount of light reflected from the product’s surface 0 = dull to 15 = shiny Adherence of coating: the amount of adherence of the coating to the product after frying 0 = no adherence to 15 = much adherence Surface attributes Roughness: the amount of particles, bumps, protrusions, or craters in the surface 0 = JELL-O® brand gelatin to 15 = FINN CRISP® rye wafer Surface greasiness/oiliness: the amount of oil on the surface 0 = unsalted saltines to 7a = hot dog (did not have a numerical reference for 15) First bite Hardness: the force to compress between the molars 1a = cream cheese to 14.5a = LifeSavers® hard candy Cohesiveness: the degree to which sample deforms rather than crumbles, cracks, or breaks. 1a = cornbread muffin to 15 = Freedent® chewing gum Crispiness: the force and noise with which a product breaks or fractures (rather than deforms) when chewed with molar teeth (1st and 2nd chew). 2a = Quaker low fat granola bar to 17a = Melba toast Chew down Cohesiveness of mass: the degree to which a chewed sample (at 10 to 15 chews) holds together in a mass 0 = shoestring licorice to 15 = raw Pillsbury® biscuit dough After swallowing (or expectorating) Residuals: the amount of particles remaining in the mouth after swallowing 0 = no particles to 15 = many particles (4.5 = cooked spaghetti) Tooth packing/tooth sticking: the degree to which product sticks on the surface of the teeth 0 = canned mini clams to 15.0 = Jujubes candy Mouthcoating (oily): the amount of greasiness/oiliness remaining on the mouth surface 5a = Great ValueTM brand canned/baked biscuits to 9a = Pillsbury® GrandsTM baked biscuits aSome attribute scales were well defined in Meilgaard and others (1999), but do not have intensity references for the values of 0 or 15 or were developed at Southern Regional Research Center (SRRC). References for the extreme ends of the scale were not identified or found.

adding various amounts of deionized water to 50 g of the solid mix- was full. Carbon dioxide (65 mL) was used to extract the sample at ture to achieve a viscosity of 1440 to 1740 cP (120 to 145 RVU). The 7500 psi and 100 °C, and the restrictors were set at 140 °C. The flow slurry was then used for okra coating and frying. rate was 2.5 to 2.7 mL/min (Shih and others 2004). The oil content was calculated from the weight gain of the oil collected in tubes Coating and frying of okra packed with 1.5 g of glass wool during the extraction. A 5.7-L Dazey deep-fryer (Dazey Co., New Century, Kans., U.S.A.) with a strainer was used for the frying experiment. The Sensory analysis heating was controlled by a temperature controller, Therm-O- Ten panelists trained in the principles and concepts of descrip- Watch L6-1000SS (Instruments for Research and Industry, Chelten- tive analysis (Meilgaard and others 1999) and 1 to 10 y of experience ham, Pa., U.S.A.). The oil bath, filled to a depth of 4.5 cm with 1.4 L participated in the study. The panelists were screened for interest, of the vegetable oil, was heated at 177 °C. availability, and normal abilities to determine textural intensities. Okra pieces were dipped and coated evenly in the batter slurry During the original training process, panelists learned fundamen- before being dropped into the fryer. After frying for 7 min, the bat- tal properties of sensory evaluation, how to describe textural prop- ter-coated okra was cooled on the strainer and weighed. The fried erties in common food products, development of texture definitions batter crust was peeled from the okra and weighed. It was then and methods of evaluating texture, and developing intensity scales ground in liquid nitrogen, and the resulting powder was used for oil for individual sensory properties. The fried okra lexicon used was analysis. developed at the USDA’s Southern Regional Research Center (SRRC). It included 5 appearance and 10 texture attributes (Table 1). Oil analysis The appearance attribute scales were developed exclusively for Oil content was analyzed using a supercritical fluid extraction fried okra. Panelists were given anchors for the extreme ends of the system (SFX 220, ISCO, Lincoln, Nebr., U.S.A.). The sample cartridge scale. The line scale was unstructured, and panelists were instructed was loosely filled with 1 g of Ottawa sand (EM Science, Gibbstown, to mark the line at the point that placed the sample in proportion to N.J., U.S.A.) at the exit end of the cartridge, followed by 1 g of diato- the extreme reference points. Anchored intensity line scales were maceous earth and 1.5 to 3.0 g of ground batter until the cartridge used to evaluate the texture attributes (Meilgaard and others 1999).

URLs and E-mail addresses are active links at www.ift.org Vol. 70, Nr. 1, 2005—JOURNAL OF FOOD SCIENCE S19 S: Sensory & Nutritive Qualities of Food www.ift.org 45.5 44.5 45.545.545.545.5 52.1 51.1 47.6 45.0 URLs and E-mail addresses are active links at Results and Discussion a Oil uptake Solid content For sensory evaluation, fried okra samples were prepared by For practical purposes, the addition of PGRF is required to devel- When rice batter slurries were prepared containing a constant When rice batter slurries of the fried bat- Batter viscosity not only affected the oil uptake 44.6 ± 0.3 44.0 ± 0.2 29.0 ± 0.128.5 ± 0.622.0 ± 0.2 26.3 ±24.5 0.6 ± 1.1 27.3 ± 0.9 28.0 ± 1.0 29.2 ± 1.0 Sensory evaluation Sensory evaluation Effect of PGRF Effect of PGRF Effect of batter viscosity Effect of batter viscosity using 3 different batter formulations, based on the main flour com- and mixed rice flour rice flour, ponent used, including wheat flour, op the needed viscosity and enhance the coating properties for the a to offset the effect of viscosity on oil uptake, However, rice batter. comparable batter viscosity in the range of 1440 to 1740 cP (120 to 145 RVU) was established for all the batters by adjusting the water 2. As the batter viscos- Table in also shown are The results content. ity is now comparable, oil uptake of the fried batters depends solely the oil uptake of the fried on the batter composition. Noticeably, rice-batters remains substantially lower than that of the wheat in absorb- indicating the unique ability of rice ingredients batter, the oil uptake of rice batters as ing less oil during frying. However, a group remains practically unchanged, with or without the addi- the addition of PGRF in small amounts Apparently, tion of PGRF. (<8%) was less of a factor on oil uptake when the viscosity was ad- which justed to a comparable level, than the 92% plus rice flour, dominated the frying of the batter. properties total solid content, batter viscosity changed, depending on the total solid content, batter viscosity changed, traditional wheat flour batter composition. For comparison, the 2, the batter of rice Table in As shown batter was also prepared. cP (46.8 RVU). It in- flour alone had the lowest viscosity of 561 the vis- At 8% PGRF, in the rice batter. PGRF with increased creased that of the traditional cosity was 2340 cP (195 RVU), surpassing and it viscosity, with increased uptake decreased Oil wheat batter. to the 5% reached a low of 22% oil at the viscosity corresponding in PGRF and viscosity. rising with further increases before PGRF, was invariably substan- Nevertheless, the oil uptake of rice batters than that of the wheat batter. tially lower Batter operation. of the food-coating but also the effectiveness ter, are too thin to coat okra viscosities lower than 1200 cP (100 RVU) in a poorly formed resulting batter crustrelative- with a effectively, hand, batters with ly high percentage oil uptake. On the other are too thick to coat the higher than 2400 cP (200 RVU) viscosities puffy fried batter overly and in a lumpy resulting okra evenly, are often undercooked crust. Also, the thick and uneven coatings percentage oil-uptake and result in inconsistent or unusually low values. Sensory evaluation Effect of PGRF Effect of batter viscosity Sensory evaluation Sensory evaluation Effect of PGRF Effect of PGRF Effect of batter viscosity Effect of batter viscosity samples adjusted with water to achieve a comparable batter viscosity. batter a comparable to achieve samples adjusted with water

—Vol. 70, Nr. 1, 2005 70, Nr. —Vol. AB AB AB 2003 1509 (%) (cP) (%) (%) JOURNAL OF FOOD SCIENCE Experimental design for the sensory data was a randomized 20 -level set at 0.1. A = samples prepared at a constant batter solid content; B = a constant batter solid content; A = samples prepared at Statistical analysis Statistical analysis S complete block design with panelists as blocks. Analysis of variance was accomplished on each sensory attribute with PROC GLM (SAS, HSD (honest- Tukey’s N.C., U.S.A.). 8.2, 1999-2001, Cary, Release ly significant difference) was used for mean comparisons with the ␣ Texture scales were universal for all foods and not specific for fried universal for were scales Texture uniquely developed for each texture attribute okra. Each scale was 1999) and anchored with 2 or more points (Meilgaard and others Texture products. the attribute in commercial using the intensity of products so that intensity references are selected from commercial to help the pan- they represent the attribute at different intensities attributes (Meilgaard elists set the scale in their minds. Published panels from 2 food re- and others 1999) were developed by trained at SRRC attributes developed Texture or technical centers. search guidance of a qualified were developed by our panelists under the attribute and give food items with the texture They take panel leader. come to consensus on scores to the attribute. The group of panelists intensity exceeds the score for each anchor (food product). If attribute none of our samples ap- 15, the scale can be expanded; however, at 15 with most sam- proached 15, so we left the line scale end-point at or below 15. Scores ples having the highest anchor at an intensity (Compusense FIVE, were recorded on a computerized ballot system The study consisted of Compusense Inc., Guelph, Ontario, Canada). presented, immediately 2 sessions in which fried okra samples were Styrofoam plates, at 15- after cooking, draining, and portioning onto fluorescent lights. A min intervals and analyzed under cool white evaluated during were a and 3 experimental samples “standard” presented twice during taste session. Each experimental sample was samples consisted of 5 pieces of fried okra Each panelist’s the study. “standard,” The formulationfor evaluation of texture. within a given product, was presented which was a commercially available fried okra and served as a means and scored at the beginning of each session of calibration for the panelists. In addition, this data served as a point of discussion for relating the experimental products to a commercially available product. Panelists were divided into 2 groups for sensory assessments. At a large table, 1 group assessed the appearance of 1 shared sample in which 2 of the 5 fried okra pieces were halved to conducted the other group whereas view, a cross-sectional provide texture evaluations at individual test stations. Each group rotated so that appearance and texture descriptors were evaluated by each panelist for all samples. All panelists evaluated appearance on the same 5-piece sample and evaluated texture on their own 5-piece sample. Distilled, filtered water (Hydrotech drinking water filtration was used to cleanse the mouth be- U.S.A.) Calif., Valencia, system, tween samples. 100989592(wheat) a 0 2 5 8 561 546 1350 2345 1504 1558 1671 1715 Batter compositionRFviscosity Batter PGRF Table 2—Oil uptake of fried okra as a function of batter composition of batter as a function okra of fried 2—Oil uptake Table Statistical analysis Statistical analysis Statistical analysis Rice batter coated fried okra . . . . . okra fried coated batter Rice

S: Sensory & Nutritive Qualities of Food Rice batter coated fried okra . . .

(a mixture of rice flour with 5% PGRF). Evaluations were conducted from the others. The mixed rice flour and the rice flour formulations according to the attributes as shown in Table 1, and results of the were significantly crispier than the wheat flour formulation, which evaluation are shown in Figure 1. is likely a positive attribute. Of the after-swallowing texture attributes, mouth coating did not change between the 3 formulations. Appearance The residual particles were higher in the mixed rice flour formula- The 3 formulations did not differ significantly in evenness of tion than the wheat flour. The rice flour was not different from the coating, surface consistency, surface shine, or adherence of coat- other 2 formulations. The tooth packing/tooth stick was significant- ing. Of the 5 visual properties, including color description, evenly higher in the mixed rice flour formulation than the other 2 for- ness of coating, surface consistency, surface shine, and adherence mulations. Tooth packing/tooth sticking is the only attribute that of coating, only color description resulted in a statistically signifi- may need some adjustment. It is not known how far from commer- cant difference. The color of the mixed rice flour formulation result- cially available products that this attribute can go and still be ac- ed in a desirable golden brown product (intensity score of 7.1). ceptable to consumers. Meanwhile, the wheat flour (3.1) and the rice flour (3.0) formulations gave a lighter and more yellow product. The mixed rice sam- Conclusions ple with its golden brown color looked more like the golden brown ow oil-uptake batters for the coating of okra have been formu- of the commercial sample used for calibration at the beginning of L lated using rice flour and small amounts of the modified rice the panel than the wheat-based batter did, which indicates that it flour PGRF. The addition of PGRF provided the needed viscosity to was in the commercially acceptable range. the batter slurry for coating, and, at 5%, effectively lowered the oil uptake of the fried batter by up to 51% compared with that of the Mouth-Feel wheat batter. Based on the sensory evaluation, the same batter has Of the 2 surface texture properties, roughness and surface greas- some superior properties, such as crispiness or cohesiveness, which iness, only roughness had any significant difference. The 2 rice are quite desirable. It has good browning properties. Its tooth pack- formulations appeared to be slightly rougher than the wheat for- ing/tooth stick properties are a little high, but probably not out of mulation. Commercial products can have cornmeal added, which the range of consumer acceptability. makes them quite rough. Therefore, the greater roughness of the rice flour and mixed rice flour treatment may not be an issue with Acknowledgments consumer acceptance. We would like to thank Myrna Franklin for her participation and Hardness, cohesiveness, and crispiness were 1st-bite properties assistance in the okra coating and frying experiments. and resulted in mean differences that were statistically significant. The rice flour formulations were harder than the wheat flour formu- References lation, but the rice flour formulation was not out of the normal range Balasubramaniam VM, Chinnan MS, Mallikarjunan P, Phillips RD. 1997. The effect of edible film on oil uptake and moisture retention of a deep-fat fried of the commercially available product (mean of commercial prod- poultry product. J Food Proc Eng 20:17–29. uct is 5.4 ± SE of 0.52). The cohesiveness in mixed rice flour formu- Duxbury DD. 1989. Oil/water barrier properties enhanced in fried food batters. Food Proc 50(2):66–7. lation was significantly less than in the wheat flour formulation. Gallagher E, Gormley TR, Arendt EK. 2004. 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St. Paul, Minn.: American of 3 fried okra samples with batter coatings of rice flour Assn. of Cereal Chemists. p 595–609. batter, wheat flour batter, and mixed rice flour batter con- Zain AM, Ahamad ZC. 1985. Formulation and acceptance of rice-based baby food. Asian Food J 1:146–8. taining 5% pregelatinized rice flour

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