TECHNOLOGICAL AND NUTRITIONAL ASPECTS OF UTILISATION OF TRITICALE FOR EXTRUDED FOOD PRODUCTION

Aleksandra Marciniak, Wiktor Obuchowski, Agnieszka Makowska
Institute of Food Technology of Plant Origin, University of Life Sciences in Poznań, Poland

ABSTRACT

The comparison of six triticale varieties as a source of certain nutritional components, evaluation of technological and nutritional properties of triticale milling products like flour, bran and whole-meal flour were done. It was found, that new triticale varieties have biochemical and rheological properties similar to wheat raw material required for cookie and extruded products. Triticale milling products, especially whole grain flour and bran are valuable from nutritional point of view with regard to high polyphenols and soluble fiber content and also antioxidative properties. Extrusion process has small destructive effect on polyphenols content, but improving effect on antioxidant activity and soluble dietary fiber content. It was found, that extruded products including 30% of triticale bran have in most of cases good consumer sensory properties, with high amount of soluble dietary fiber and substantial antioxidative properties.

Key words: triticale, polyphenol content, antioxidant activity, extrusion, soluble dietary fiber, farinograph characteristics.

INTRODUCTION

Triticale is a man made cereal crop genus created from crosses between wheat Triticum sp. and rye (Secale cereale L). Intense breeding and selection have made very rapid genetic improvements in triticale grain quality [3,10,11]. This cereal is a speciality of polish breeding. The area of triticale cultivating in Poland, in 2006 year, was about of 1 mln ha. Its production in Poland is growing every year and in 2005 it was even higher in comparison to rye production, with a total of about 3.7 mln ton [5,6,18] (Table 1).

It should be assumed that in the future rye production will be still going down and it will be gradually replaced with triticale. The problem is that triticale in Poland is used only as fodder and raw material for non-food production. The level of its utilisation for food in comparison to wheat, rye and even oat or barley is marginal. It is a fact that utilisation of triticale flour for breadmaking is complicated and still not successful. Nevertheless, in opinion of many specialists, new varieties of triticale grain positively changed in comparison to old, very unstable varieties , and on account of their good nutrional value they should be successfully used as a raw material for food [4,11,14], especially extruded products as well as in wafer and cookie production [4,7,8,12] on account of its good nutritional value.

The aim of the work is the comparison of some triticale varieties as a source of certain nutritional components, evaluation of technological and nutritional properties of triticale milling products such as flour, bran and whole-meal flour. The aim of the work is also the estimation of the possibilities to use this crop as a raw material for functional (extruded) food products.

MATERIALS AND METHODS

Grain and flour of one spring triticale variety: Dublet, and five winter varieties: Grenado, Sorento, Baltiko, Woltario and Zorro, obtained from Danko Harvesting Station were analysed. Triticale grain, after its technological characterisation, was milled in the Brabender Quadrumat Senior Mill and flours standardized to yield of 60% were used in the experiments. The technological properties of flour were evaluated on the basis of protein content, ash content, falling number, Zeleny sedimentation test and farinograph characteristics according to AACC Official Methods [1].

At the next step poliphenols content and antioxidative activity according to Folin-Ciocalteu method [16], towards ferulic acid were evaluated Soluble and insoluble dietary fiber content in flour, whole grain and bran were determined according to Asp method [2].

At the final step triticale bran was used to make an extruded product from the mixture of triticale bran and corn grits (ratio 30:70). Extrusion process was carried out using single-screw extruder, type Metalchem S-45. Extrusion process parameters were following: temperature of first barrel zone 120°C, second 150°C, head and shaping die 120°C, screw rotation 82/min. The expansion ratio, bulk density and sensory characteristic, as well as functional components of the extruded products were evaluated.

RESULTS AND DISCUSSION

The evaluated triticale varieties were characterized by large, distinguished grain, with test weight above 70 kg·hl^-1. Much lower test weight in comparison to wheat grain suggest, that the endosperm of the triticale grain is more floury and not so compact, and the surface of the grain is still wrinkled. Winter varieties were characterized by bigger grain. The grain of all varieties showed good milling properties, between 60.3% (Baltico) and 66.7% (Dublet) (Table 2). The milling properties of triticale varieties were relatively  much better than common rye grain, and similar to obtained from wheat grain [13].

The ash content in the flour of triticale varieties ranged from between 0.44 to 0.67%. Higher values of ash content showed winter varieties Sorento and Baltico. Protein content in all but one triticale variety (Grenado) was  between 11.9-12.8%. The falling number of four varieties was above 135s, and only Wolatrio variety showed high amylolytic activity on the level of 71s (Table 3). It suggest, that most of triticale varieties are not so supposed on sprouting process like years earlier, but still have amylolytic activity higher in compare to wheat. Nevertheless, not so high values of falling number and relatively low protein content of triticale gives results similar to wheat flour useful for cookie goods.

The same suggestion gives results of farinograph evaluation of triticale varieties. Rheological properties of triticale dough evaluated on the basis of farinograph characteristics (Table 3) are very similar to properties of wheat varieties required for cookie production. Analyzed varieties shoved great differentiation of water absorption, low: Grenado, Voltario and Zorro (50 to 51.8%) and quite high Baltico (61.7%). In addition, gluten of all triticale varieties showed weak protein matrix (Fig.  1). On the whole: specific biochemical properties of triticale flour expressed  in amylolytic activity and weak gluten protein characteristic indicate, that it could be a good raw material for cookie and extruded products [4,12].

From nutritional point of view analyzed grain of triticale varieties, and  especially bran and whole-meal flour are a valuable source of polyphenols and fiber substances. All the whole grain flours showed the best antioxidative activity value (Table 4).

The fiber content in triticale grain is similar to one in average wheat grain [1].  It was established (Table 5), that  whole grain flour is richer in total dietary fiber substances, as well as water soluble and insoluble fractions in comparison with patent flour. Whole grain however has the higher ratio of insoluble/soluble fiber in comparison to patent flour. From nutritional point of view it would be valuable if the amount of soluble fiber in patent flour was at the same level as in the whole grain.

It was observed, that the extrusion process of bran from evaluated varieties of triticale has decreasing effect on polyphenols content in extrudates (Fig. 2 ). On the other hand extrusion has as a result a positive effect on antioxidative properties of the product (Fig. 3). It should be assumed, that in spite of destruction of polyphenols, the total antioxidative properties are better because of the new compounds created in gentle Maillard reaction. The extrudates are also characterized similar amount of total fiber content but much higher level of soluble dietary fiber in comparison with raw material (Fig. 4, 5). Similar results according to soluble fraction of fiber observed Rzedzicki and Zarzycki  [15] in their research.

The results of sensory characterization of extrudates with 30% of triticale flour are in the Table 6. Most of the extruded products showed good consumer properties: good porosity, texture, expansion ratio, color and taste. The best results obtained for Zorro and Dublet varieties. Somewhat lower total score for Baltico was the result of a little higher hardness, specific flavor and color of extrudates.

CONCLUSIONS

The specific characteristic of triticale grain and triticale milling products indicates, that it could be a good raw material for extruded products. The best extrusion performance show varieties Dublet and Zorro, but other varieties are also valuable raw material, which could be used to increase the assortment of nutritional products rich in fiber and antioxidative substances.

The results of investigation indicates, that high level of total and soluble dietary fibre, good antioxidative properties and specific protein composition of triticale varieties grown in Poland are the reasons for using them for production of the group of products mentioned above. It should be also assumed, that permanent study concerning variety selection, grain preparation for milling, milling to whole grain flour, selection of the best extrusion parameters and/or addition of some other components gives the possibility to create a new, nutritionally valuable products belonging to functional food on the basis of domestic triticale grain, which could be a Polish regional contribution to world food market.

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Accepted for print: 8.10.2008

Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.