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Transactions of the Society of Refrigerating and Air Conditioning Engineers, OriginalOriginal paperPaper Vol.35,No.3(2018),pp.205-210,Transactions of doi:the Japan10.11322/tjsrae.18-15FB_OA Society of Refrigerating and Air Conditioning Engineers, Received date: MayReceived 30, 2018; date: J-STAGE May 30, Advance2018; J-STAGE publishied Advance date: Julypublished 15, 2018 date: July 15, 2018 doi: 10.11322/tjsrae.18-15FB_OA

Quality Changes of Commercial -based Products after Frozen Storage

Ru JIA, Mami EGUCHI, Wei DING, Naho NAKAZAWA, Kazufumi OSAKO, Emiko OKAZAKI

* Department of Food Science and Technology, Tokyo University of Marine Science and Technology (4-5-7 Konan, Minato-ku, Tokyo 108-8477)

Summary In a preliminary study to clarify the factors affecting the quality deterioration of surimi-based products, the physical properties and drip loss of five different types of commercial surimi-based products (Itatsuki-, , Satsuma-age, Datemaki, and Hanpen) at different freezing conditions were evaluated. After frozen storage, the breaking strength and breaking strain of Itatsuki-kamaboko, which is a two-stepÐheated surimi gel without starch, decreased with frozen storage, while for the other products, which are direct-heated gels containing starch, the breaking strength and breaking strain increased. Drip loss increased after frozen storage, and the thawing drip was higher with Itatsuki-kamaboko than with other products. These changes were notable in samples subjected to slow freezing than subjected to quick freezing. Moreover, the results of physical properties and drip loss corresponded to the change in sensory characteristics. Thus, the quality change in frozen surimi-based products might be correlated to not only the freezing conditions but also the heating methods and ingredients used.

Keywords: Surimi-based product, Frozen storage, Freezing speed, Heating method, Physical property, Drip loss, Sensory evaluation

1. Introduction 2. Materials and Methods

Low-temperature preservation (freezing in 2.1 Materials particular) is a common method used for many kinds Five types of typical commercial surimi-based of food, such as meat, fish, and , to prevent products, Itatsuki-kamaboko (steamed kamaboko), physiological and chemical changes. Freezing is also Chikuwa (grilled kamaboko), Satsuma-age (fried important for commercial surimi-based products, kamaboko), Datemaki (grilled kamaboko with egg especially during periods of high demand, such as at yolk), and Hanpen (boiled kamaboko) were obtained the start of the new year in Japan, despite the belief from a supermarket (Tokyo, Japan). Samples and that gelled food like surimi-based products is their ingredients are listed in Table 1. Among them, susceptible to damage by freezing. Although reports Itatsuki-kamaboko is processed by two-step heating, have shown that protein denaturation, ice crystal and others are processed by direct heating. formation, etc., during freezing and frozen storage affect the quality of frozen meat or fish1-4), limited 2.2 Freezing and thawing information on the freezing of gelled products such Samples were cut into 25 mm cubes, vacuum- as surimi-based products is available, and the packed in plastic bags, and frozen either (A) quickly, relationship between freezing conditions and quality by immersion in −40¡C ethanol or (B) slowly, by changes in surimi-based products has not been freezing in a −20¡C freezer. The frozen samples clarified. were stored at −20¡C for 2 and 21 days and thawed Currently, surimi-based product manufacturers at 4¡C overnight before use. establish freezing conditions based not on scientific evidence but on experience. Thus, there is a need to 2.3 Determination of physical properties clarify the quality changes in surimi-based products The physical properties of samples were evaluated during freezing and frozen storage and provide by the puncture test using a rheometer (RE2-3305B; manufacturers with a scientific basis for optimal Yamaden Co., Tokyo, Japan). The plunger was processing conditions. In this study, as the first step spherical, with a diameter of 5 mm and a depression of the investigation to clarify the factors affecting speed of 1 mm/s. Samples were kept at 0¡C and the quality deterioration of frozen surimi-based measured for breaking strength (g) and breaking products, we investigated the quality changes in five deformation (mm). Each measurement was repeated different types of commercial surimi-based products four times. during frozen storage, comparing the changes in physical properties, drip loss, and sensory characteristics.

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Table 1. Kinds of kamaboko Sample Product name Ingredient Heating method A Itatsuki-kamaboko Surimi (Croaker), Sugar, , Egg white, Salt, Steamed (Two-step Seasoning; heating) B Chikuwa Surimi, Potato starch, Sugar, Egg white, Glucose, Salt, Grilled (Direct heating) Vegetable oil, Lard, Seasoning; C Satsuma-age Surimi (Herring, Cod, Horse mackerel, Croaker, others), Fried (Direct heating) Soybean protein, Potato starch, Glucose, Seafood extract, Salt, Seasoning, Sugar, Vegetable oil; D Datemaki Egg, Surimi, Sugar, Egg white, Seasoning, Starch, Grilled (Direct heating) Seafood extract, Salt, Modified starch, Emulsifier; E Hanpen Surimi, Egg white, Starch, Sugar, Yam, Mirin, Boiled (Direct heating) Vegetable oil, Salt, Seafood extract, Thickening polysaccharides, Spice, pH regulator

2.4 Determination of drip loss Traditionally, physical properties, including Drip loss included thawing drip (TD) and breaking strength and breaking deformation, are the expressible drip (ED). The TD was determined by main functional properties of surimi-based products. measuring the sample weight (W1) and drip weight These properties are also primary indicators of the (W2) of samples using No. 5 filter paper and was quality of surimi-based products6-9). calculated using equation (1). The breaking strength and breaking deformation TD (%) = W2/W1 × 100 (1) results for five commercial surimi-based products The ED was measured based on the method of before freezing are shown in Fig. 1. It was suspected Shimizu5) with slight modifications. A slice of that the change after 2 days would reflect the effect sample (2 mm thick and approximately 1.0 g in of freezing itself, and the change after 21 days weight) was placed between two filter papers for a would reflect the effect of frozen storage at −20¡C. compression test on a RE-3305B rheometer under 10 The breaking strengths for Itatsuki-kamaboko, kg/cm2 pressure for 20 s. Samples were weighed Chikuwa, Satsuma-age, Datemaki, and Hanpen were before (W1) and after compression (W2), and the 790, 293, 196, 84, and 80 g, respectively. In the ED was calculated using equation (2). processing of surimi-based products, grinding with ED (%) = ((W1 − W2)/W1) × 100 (2) salt and heating are the most important steps10). Grinding with salt can increase the ionic strength of 2.5 Sensory evaluation fish meat, thus increasing actomyosin solubility and Commercial products (Itatsuki-kamaboko and generating a sol form. Heating below 40¡C, called Chikuwa) were obtained from a supermarket, Òsuwari,Ó can change its rheological properties from subjected to slow freezing and stored at −20¡C. the sol form to gel11). Due to the formation of a Frozen samples were then thawed at 4¡C overnight protein network structure, heating at high after 2-week frozen storage. Sensory evaluation of temperatures after suwari heating (two-step heating) samples before and after frozen storage was produces increased gel strength12). Therefore, due to performed by nine panelists from the Food the two-step heating processing method of Itatsuki- Processing Laboratory of Tokyo University of kamaboko13), it had the highest breaking strength Marine Science and Technology. The panelists before freezing. Chikuwa is typically heated at 130Ð included four males and five females aged 20 to 40. 180¡C until the center temperature reaches 75¡C; The appearance, elasticity, smoothness, and moisture Satsuma-age is heated to 160Ð200¡C in oil; Hanpen levels were evaluated, comparing thawed samples to is boiled at 85Ð90¡C; and Datemaki is grilled. unfrozen samples. A seven-point scale was used: 3, Therefore, these four surimi-based products heated much stronger; 2, somewhat stronger; 1, slightly by direct heating had low breaking strength. These stronger; 0, unchanged; −1, slightly weaker; −2, results are consistent with previous studies9, 14, 15). somewhat weaker; and −3, much weaker) to Furthermore, Fig. 1 shows a high correlation evaluate each item. coefficient (R = 0.9784) between breaking deformation and breaking strength. These results 3. Results and Discussion indicate that surimi-based products with higher breaking strength had larger deformation values. 3.1 Physical properties Similar results were observed by Qian16).

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The breaking strength results of five surimi-based 1000 products, frozen quickly and slowly and stored for 2 and 21 days, are shown in Fig. 2. The breaking 800 A strength of Hanpen did not significantly change during frozen storage; however, for Datemaki, 600 Chikuwa, and Satsuma-age, which were processed with direct heating, the breaking strength increased 400 during frozen storage, by 67.9%, 43.7%, and 23.6%, B respectively, compared to that before freezing. Breaking strength (g) strength Breaking 200 C Conversely, for Itatsuki-kamaboko, which was E D processed with two-step heating, the breaking 0 strength with slow freezing decreased by 12% after 0 5 10 15 20 frozen storage. Changes in breaking deformation are Breaking deformation (mm) shown in Fig. 3, and the similar trends in breaking Fig. 1 Breaking strength and breaking deformation strength are displayed. It was speculated that the difference in physical of five surimi-based products before freezing. properties among the five kinds of products after Itatsuki-kamaboko (A), Chikuwa (B), Satsuma-age freezing was due to the different heating methods. (C), Datemaki (D), and Hanpen (E). Moreover, addition of starch was also considered to be the reason of increase in physical properties due 17) to the starch retrogradation . A B Quick freezing Quick freezing 1200 Slow freezing 600 Slow freezing a a a ab A B a a a bc Quick freezing Quick freezing b bc 15 800 400 20 Slow freezing Slow freezing c c a a ab b b b b a 15 b b c bc 10 400 200 10 Breaking strength (g) strength Breaking Breaking strength (g) strength Breaking 5 0 0 0 2 21 0 2 21 0 2 21 0 2 21 5 Storage period (days) Storage period (days) Breaking deformation (mm) deformation Breaking Breaking deformation (mm) deformation Breaking 0 0 0 2 21 0 2 21 0 2 21 0 2 21 Storage period (days) Storage period (days)

C D Quick freezing Quick freezing 400 Slow freezing 200 Slow freezing C D a Quick freezing Quick freezing a a a 300 a 150 15 Slow freezing 15 Slow freezing b b b c c c c a a a 200 100 b 10 10 b b ab a 100 50 bc bc bc c Breaking strength (g) strength Breaking (g) strength Breaking 5 5 0 0 0 2 21 0 2 21 0 2 21 0 2 21 Storage period (days) Storage period (days) (mm) deformation Breaking (mm) deformation Breaking 0 0 0 2 21 0 2 21 0 2 21 0 2 21 Storage period (days) Storage period (days) E Quick freezing 200 Slow freezing E 150 Quick freezing 15 Slow freezing b b a 100 b c c

10 a 50 b b b

Breaking strength (g) strength Breaking c c 0 5 0 2 21 0 2 21 Storage period (days)

(mm) deformation Breaking 0 0 2 21 0 2 21 Storage period (days) Fig. 2 Breaking strength of five surimi-based products, frozen quickly and slowly and stored for 2 Fig. 3 Breaking deformation of five surimi-based and 21 days. Itatsuki-kamaboko (A), Chikuwa (B), products, frozen quickly and slowly and stored for 2 Satsuma-age (C), Datemaki (D), and Hanpen (E). and 21 days. Itatsuki-kamaboko (A), Chikuwa (B), Data are shown as means ± standard deviations. Satsuma-age (C), Datemaki (D), and Hanpen (E). Different letters indicate significant differences (P < Data are shown as means ± standard deviations. 0.05). Different letters indicate significant differences (P <

0.05).

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3.2 Drip loss sensory evaluation as representatives of two-step The drip losses from the five surimi-based products heated sample and direct heated samples, stored at −20¡C for 2 and 21 days are shown in Fig. respectively. 4. It was confirmed that Itatsuki-kamaboko became Before freezing, the EDs were 5.12%, 11.62%, watery and significantly lost smoothness after frozen 11.11%, 26.22%, and 21.55% in Itatsuki-kamaboko, storage, as shown in Fig. 5. It also displayed Chikuwa, Satsuma-age, Datemaki, and Hanpen, noticeable surface changes after frozen storage as respectively. The ED value for Itatsuki-kamaboko shown in Fig. 6. The reason for the relatively darker was the lowest. After frozen storage, the total drip color in frozen samples might be because traces of loss increased by freezing and frozen storage, and ice crystals clearly remained as voids, forming the amount was higher after 21 days than that after 2 irregularities on the surface of the product. The ease days. The total drip loss was higher in samples of formation of the ice crystals probably causes a subjected to slow freezing than that subjected to large amount of drip loss and loss of smoothness. quick freezing. Samples with slow freezing that Moreover, the taste component in the product were stored at −20¡C for 21 days had the highest flowed out with the drip loss, which might have total drip loss, which increased by 120.1%, 18.5%, influenced the taste of the product, as shown in the 153.4%, 32.0%, and 62.4% for Itatsuki-kamaboko, results. Meanwhile, Chikuwa displayed similar Chikuwa, Satsuma-age, Datemaki, and Hanpen, results for all evaluation items before and after respectively, compared to that before freezing. frozen storage. This result is consistent with the After 21 day-frozen storage subjected to slow higher TD observed in Itatsuki-kamaboko compared freezing, Satsuma-age showed high TD (3.3%), to Chikuwa. As described above, the results of the because it can absorb oil during the frying process13, drip loss and the sensory test corresponded well. 16), oil was probably also included in the TD measurement. Itatsuki-kamaboko also had a TD of

approximately 3.3%, followed by Datemaki and A Expressible drip (%) B Expressible drip (%) 15 Thawing drip (%) 20 Thawing drip (%) Hanpen at 2.0Ð2.5% and Chikuwa at 1.2%. a a a As mentioned above, Itatsuki-kamaboko was b 15 b b 10 c c c

processed by two-step heating, while the others were d 10 e e 5 Drip loss (%) loss Drip processed by direct heating. Because of the more (%) loss Drip 5 intense coagulation caused by rapid unfolding of 18) 0 0 proteins during direct heating , water is more easily 0 2 21 0 2 21 0 2 21 0 2 21 Quick freezing Slow freezing Quick freezing Slow freezing sealed in such a network configuration after low- Storage period (days) Storage period (days) 19) temperature heating ; hence, two-step heated gel was expected to produce less drip. However, after C Expressible drip (%) D Expressible drip (%) 40 Thawing drip (%) 40 Thawing drip (%) frozen storage, the opposite result was observed, and a a b a c high TD was generated in Itatsuki-kamaboko. A 30 30 d d b c c similar trend was observed by Akahane, who 20 20 d d Drip loss (%) loss Drip observed that low-temperature-heated surimi gel (%) loss Drip 10 10 released more water than did high-temperature- 20, 21) 0 0 heated gel under storage with vacuum-packed 0 2 21 0 2 21 0 2 21 0 2 21 Quick freezing Slow freezing Quick freezing Slow freezing condition. It was presumed that the difference in the Storage period (days) Storage period (days)

degree of water entrapped inside the gel would be

related to the generation of released water. Although E Expressible drip (%) the phenomenon of higher TD in Itatsuki-kamaboko 40 Thawing drip (%) a b can be explained by Akahane's hypothesis, further 30 c c d d investigation is still needed. Moreover, unlike other 20

products, Itatsuki-kamaboko was produced without (%) loss Drip 10 addition of starch, which may also be the reason for 0 the higher TD. 0 2 21 0 2 21 Quick freezing Slow freezing 3.3 Sensory evaluation Storage period (days) For the results of TD, Itatsuki-kamaboko and Chikuwa had the highest and lowest values, Fig. 4 Drip loss of five surimi-based products respectively. For the results of physical properties, stored at −20¡C for 21 days. Itatsuki-kamaboko (A), Itatsuki-kamaboko decreased, whereas Chikuwa Chikuwa (B), Satsuma-age (C), Datemaki (D), and increased after frozen storage. It was speculated that the quality changes were related to the different Hanpen (E). Data are shown as means ± standard heating methods. Therefore, to verify whether the deviations. Different letters indicate significant sensory quality has the same tendency, Itatsuki- differences (P < 0.05). kamaboko and Chikuwa were selected for the

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Itatsuki-kamaboko Before freezing After freezing

4

2

0

Taste Sensory scores Sensory -2 Elasticity Wateriness Smoothness -4 Evaluation items

Chikuwa

4

2

Itatsuki-kamaboko 0

Taste Sensory scores Sensory -2 Elasticity

Wateriness Smoothness

-4 Evaluation items

Fig. 5 Sensory scores of Itatsuki-kamaboko and Chikuwa after frozen storage. Data are shown as means ± standard deviations. Chikuwa 4. Conclusion Fig. 6 Images of Itatsuki-kamaboko and Chikuwa The results indicate that different types of before and after frozen storage. surimi-based products displayed different tendencies of physical property changes and drip loss during References frozen storage. The breaking strength of Itatsuki- kamaboko (two-step-heated product) decreased 1) Petrović, L., R. Grujić, and M. Petrović, Definition of during frozen storage, while for Chikuwa, Satsuma- the Optimal Freezing RateÑ2. Investigation of the age, and Hanpen (direct-heated products), the Physico-chemical Properties of Beef M. longissimus breaking strength increased after frozen storage. dorsi Frozen at Different Freezing Rates, Meat Drip loss increased after freezing in all samples, Science, 1993, 33(3), pp. 319-331. with a higher thawing drip for Itatsuki-kamaboko 2) Chevalier, D., A. Sequeira-Munoz, A. Le Bail, B.K. than that of the others. These changes were notable Simpson, and M. Ghoul, Effect of Freezing in samples with slow freezing but were slight with Conditions and Storage on Ice Crystal and Drip quick freezing. In conclusion, heating and freezing Volume in Turbot (Scophthalmus maximus): conditions, as well as ingredients such as starch, Evaluation of Pressure Shift Freezing vs. Air-blast Freezing, Innovative Food Science & Emerging may influence the quality changes in surimi-based Technologies, 2000, 1(3), pp. 193-201. products after freezing and frozen storage. 3) Suvanich, V., M. Jahncke, and D. Marshall, Changes in Selected Chemical Quality Characteristics of Acknowledgements Channel Frame Mince during Chill and Frozen Storage, Journal of Food Science, 2000, 65(1), This study was supported by the project ÒTohoku pp. 24-29. 4) Fukuda, Y., Denaturation by Freezing of Fish Muscle Marine Science Center ProjectÓ from Ministry of Proteins, Bulletin of the National Research Institute Education, Culture, Sports, Science and Technology, of Fisheries Science,1996, 8, pp. 77-92. (in Japanese) Japan. 5) Shimizu, Y., I. Fujita, and W. Simidu, Water

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