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Effect of krill powder on baking properties and its application to bread crumbs having low oil-absorbing ability

M. Tomita1, T. Maeda2, Y. Maehara3, M. Yamaoka3 and N. Morita3

1Product Research and Development Center Hachioji Office, Nippon Suisan Kaisha, Ltd., 559-6 Kitano-machi, Hachioji, Tokyo 192-0906, Japan.
Department of Life and Health Sciences, Hyogo University of Teacher Education, 942-1, Shimokume, Yashiro, Hyogo 673-1494, Japan.  
Lab. of Food Chemistry, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1, Gakuen-cho, Sakai, Osaka 599-8531, Japan.


Bread crumb powder is made after pulverizing and or drying bread and its quality is also affected by the baking properties. When the bread crumb powder is used for fried foods, the main qualities, such as softness, shortness and brown colour after the absorbing oil have been essentially required. In addition, recently the low oil-absorbing ability has been demanded for body weight reduction and calorie control. To lower the amount of absorbed oil, normally dietary fibers have been used, however the bread crumb powder was very hard and the quality was not favorable as the final product. Therefore, krill powders have been considered to keep good texture and low oil-absorbing ability of bread crumb powder as a new additive instead of dietary fiber. The krill powders have been used only for fishing bait, though they are highly nutritious. Furthermore, large amounts of krill fish resources have not been adequately used. In this study, the effects of krill powders on baking properties were investigated to develop bread crumb powders with favorable qualities.

Materials and methods

Flour and additive

The flour used in the present study was commercial hard-type wheat flour, ‘Cameria’ donated from Nisshin Flour Milling Co., Ltd (Hyogo, Japan). Additives including native krill-shell powder (KSP), whole krill-shell powder (WK) and 6 kinds of KSPs by chemical treatments and polydextrose (PD) were added to the bread ingredients as shown in Table 1. Since the PD has been used for breadmaking to lower oil-absorbing ability of bread crumb powders in food industries, amounts added of KSPs or PD were the same as those of commercial products.


Breadmaking was conducted according to the sponge-dough method (AACC 10-11, 2000) using the compositions of ingredients as shown in Table 2. KSPs, WK and PD were added to the flour to make the sponge-dough by the first long fermentation.

Bread qualities

Loaf volume of the bread and firmness of breadcrumbs during storage were determined using the same apparatuses and methods as the previous reports (Maeda et al, 1999; Maeda et al, 2001; Maeda et al, 2004). Appearance of breadcrumbs was determined by an image analysis system (Image Hyper, DigiMo Co., Ltd., Osaka, Japan). Namely, after baking and storage for 45 min, the loaves were sliced into 4 pieces from the central portion by an electric cutter, and it was copied by Canon 5020 and scanned by CanoScan 676U/N1240U (Canon Co., Ltd., Tokyo, Japan). The image analysis of crumb grain of scanned areas (160,000 mm2) was conducted according to the manufacturer’s manual (Image Analysis System Operator Manual Ver 4.8, DigiMo, Osaka, Japan) (Kim et al, 2005).

Dough properties

Mixing properties of dough samples including KSPs or PD were evaluated by a farinograph (AACC 54-21, 2000) and a rheometer (Fudo Rhometer, Rheotech Co., Ltd., Tokyo, Japan) as reported previously (Maeda et al, 2001; Morita et al, 2002a; Morita et al, 2002b; Kim et al, 2005). Concerning rheological properties, dough samples were mixed for 15 min using suitable amount of water absorption by the farinograph, packed into a plastic case (25 mm i. d. x 25mm) and hold them at 30 oC for 10 min. Thus prepared samples were compressed at 10 mm of penetration depth using acrylic resin columnar plunger (Product No. 9, 10 mm i. d.) with 30 mm/min of test speed. The compression stress of the dough samples on the penetration was determined and data were processed by a Rheosoft TR-06 (Rheotech Co., Ltd., Tokyo, Japan). Fermentation properties of dough samples were measured by a fermograph (Atto Co., Ltd., Tokyo, Japan) as reported previously (Kim et al, 2005). Namely, the amounts of CO2 gas generated in dough samples during fermentation at 30 oC were measured according to the official manual for the fermograph. To confirm the dough appearance with additives, SEM observation of the dough was carried out by the same method as reported previously (Maeda and Morita, 2001).

Table 1. Summary of various additives for wheat flour breadmaking.



Native krill-shell powder (Protein, 30.0 %)




Whole krill-shell powder (Protein, 72.6 %)


Enzyme treated whole krill-shell powder (Protein, 62.7 %)


Enzyme treated whole krill-shell powder (Protein, 58.4 %)


Enzyme treated whole krill-shell powder (Protein, 53.6 %)


Defatted krill-shell powder


Deashed krill-shell powder


Krill chitin


Table 2. Summary of ingredients for breadmaking.





Wheat flour

180 g


Wheat flour

120 g



Amounts from optimum water absorption calculated from farinogram


Amounts from optimum water absorption calculated from farinogram






6 g



15 g



KSP, 0.6-2.0 %; PD, 5.0 %


6 g


Results and discussions

Effects of KSPs on the bread qualities

Additions of KSPs to flours did not change the specific volume or storage properties up to 1.0 %, whereas additions of 1.5 % or more decreased the loaf volume of bread samples (Table 3). Concerning appearance of breadcrumbs including KSPs, the numbers or diameter of gas cells could not be affected by additions of KSPs in the range of 0.6-1.0 % additions. The commercial bread crumb powders with a low oil-absorbing ability include KSP and PD with 0.6 % and 6.0 %, respectively, on a flour weight basis. Although the PD additions did not show significant differences on the gas cell distributions as compared with control sample without additives, the numbers of gas cells were the smallest among all samples. Normally, the low specific volume of bread with small diameter or numbers of gas cells would lower the oil-absorbing ability of its bread crumb powder. The PD addition distinctly lowered the loaf volume regardless of the presence of KSPs, therefore it might lower the oil-absorbing ability of bread crumb powder. However, there are some problems on the texture of final products, and low specific volume could decrease the sensory value of bread crumb powders. On the other hand, the bread crumb powders including KSPs have been reported to decrease the oil-absorbing ability. Therefore, from the present results, the KSP additions up to 1.0 % were expected to become new additives for bread crumb powder having a low oil-absorbing ability and provide the softness and good similar mouth feel to control sample. To determine the effects of various kinds of KSPs, six KSP preparations obtained by chemical treatments were added to the flours. The whole krill-shell powder (WK), enzyme-treated krill-shell powders (ETK I, II and III) significantly increased the loaf volume of bread, and also the WK, ETK I and II sufficiently improved the storage properties. Especially, the addition of WK including the highest amount of protein showed the largest specific volume among all samples. Since the ETKs were treated by protease, the protein portion of krill-shell was considered to improve bread qualities. The lipid or ash components in the krill-shell might not affect bread qualities from the results of defatted or deashed krill-shell powders (DFKS and DAKS). And also, the krill chitin (KC) did not influence the qualities of final products distinctly.

Table 3. Effect of krill shell powders on baking properties of breadcrumbs.

Abbreviations: Control, wheat flour without an additive. Values followed by the same letters in the same column are not significantly different (p<0.05).

Effects of KSPs on the dough qualities

Additions of KSPs to flour at 0.6 or 1.0 % amount had the same water absorption as the control, but significantly increased the stability of dough with the higher valorimeter value than that with the control (Table 4). In contrast, the PD significantly decreased the water absorption with the higher stability and valorimeter value rather than other samples. As for the rheological properties, KSPs or PD increased the compression stress of doughs, as compared with the control. Additions of all kinds of KSPs to flours also hardened the dough mixed, but significant differences were not obtained among samples. The dough samples with KSPs added in the range of 0.6-2.0 % suppressed the ratio of leaked gas to total amounts of gas during fermentation. Therefore, the KSP was considered to stabilize the gas cell membrane of the dough. This result was coincided with the SEM images as shown in Figure 1. The flour with 0.6 % KSP made relatively more viscous dough appearance than that with the control (Figures 1-A and -B). Although there was no difference in the water absorption between the control and 0.6 %-KSP flours as shown in Table 3, the quite different appearances were obtained between the two samples. In addition, the sample D with combined additions of KSP and PD might be slightly more viscous than the sample C containing PD alone, although the water absorption of the sample D was similar to the sample C (Table 3). Therefore, the flour sample including only PD made quite dry doughs among all samples, and the PD was considered to affect dough properties differently from the KSP.

Table 4. Farinograph data of various doughs.

Values followed by different letter in the same column are significantly different (p<0.05). Abbreviations and amounts of added KSP and PD were the same as in Table 3.

Figure 1 Scanning electron microscopic observation of dough. A: wheat dough; B: KSP 0.6% added wheat dough; C: PD 5.0% added wheat dough; D: KSP 0.6% and PD 5.0% added wheat dough. Abbreviations are the same as in Table 1.


Effects of KSPs on baking properties were studied to develop bread crumb powders with favourable qualities. Addition of KSPs to wheat flour could increase the stability of gas cell membrane in fermented dough, retarding the leak of generated gas during fermentation without depending on the amounts added, and this improved property coincided with the SEM images. The addition of 0.6 or 1.0 % KSPs to wheat flour made the mixed dough more stable than the control, while bread qualities, such as loaf volume, softness and gas cell distribution were maintained. Comparing the KSP with PD for their application to lower oil-absorbing ability of bread crumb powder, the KSP was expected to become an additive without restraining the good texture of bread, followed by keeping favourable properties, such as softness and good mouth feel of bread crumb powders.


The authors wish to thank the Nisshin Flour Milling Co., Ltd. (Hyogo, Japan) for donating wheat flours and J. T. Foods Co., Ltd. (Shizuoka, Japan) for providing dry yeast.


American Association of Cereal Chemists, Approved Methods, 10th Edition. (2000). Approved Method 10-11; 54-21.

Kim, J. H., Maeda, T., and Morita, N. (2005). Cereal Chemistry 82:144-151

Maeda, T., Kim, J. H., and Morita, N. (2004). Cereal Chemistry 81: 660-665.

Maeda, T., Maeda, N., and Morita, N, (2001). Journal of Applied Glycoscience 48: 27-36.

Maeda, T., and Morita, N. (2001). Journal of Applied Glycoscience 48: 63-70.

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Morita, N., Maeda, T., Miyazaki, M., Yamamori, M., Miura, H., and Ohtsuka, I. (2002a). Cereal Chemistry 79: 491-495.

Morita, N., Maeda, T., Miyazaki, M., Yamamori, M., Miura, H., and Ohtsuka, I. (2002b). Food Science and Technology Research 8: 119-124.

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