A study on nutritional characteristics of ostrich meat

Gıda Teknolojileri Elektronik Dergisi Cilt: 8, No: 1, 2013 (63-68) Electronic Journal of Food Technologies Vol: 8, No: 1, 2013 (63-68)

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Makale (Paper)

A Study on Nutritional Characteristics of Ostrich Meat Nesrin ÖZSARAÇ*, Nuray KOLSARICI**, Eda DEMİROK** * Republic of Turkey Prime Ministry-The Turkish Cooperation and Coordination Agency, Ankara-TURKEY **Ankara University, Department of Food Engineering, Ankara-TURKEY nesrinbulut82@hotmail.com

Abstract In this research, it was aimed to set forth the contribution of ostrich meat to healthy nutrition by specifying its nutritional characteristics. Ostrich meat is characterized by low intramuscular fat content, a favourable fatty acids profile (PUFA/SFA and n-6/n-3 ratios). Thus, it can be considered as a high quality product of high nutritive and dietetic value. It may thus be a valuable component of human diet. The differences between m.gastrocnemius and m.iliofibularis of ostrich in terms of the parameters which have been evaluated have also been put forward. While moisture content was found to be higher in m.gastrocnemius than in m.iIiofibularis (p<0.05), amount of fat was discovered to be greater in m. iliofibularis than in m.gastrocnemius (p<0.05).

Besides, in organoleptic evaluation, m. iliofibularis got higher points than m.gastrocnemius in terms of taste and texture parameters and these values were found to be statistically significant (p<0.05). While the amount of total saturated fatty acid in m. iliofibularis was higher than m. gastrocnemius, total monounsaturated, total polyunsaturated and total unsaturated fatty acids amounts were found to be lower (p<0.05).In addition, magnesium and copper contents were found to be higher in m. gastrocnemius, while zinc and chrome contents were discovered to be greater in m. iliofibularis (p<0.05).

Key Words: Ostrich meat, nutritional characteristic, m. gastrocnemius, m. iliofibularis

Devekuşu Etinin Besinsel Özellikleri Üzerine Bir Araştırma Özet Bu araştırmada devekuşu etinin besinsel özellikleri incelenerek sağlıklı beslenmeye olan katkısının ortaya konulması amaçlanmıştır. Devekuşu eti, düşük yağ ve yüksek çoklu doymamış yağ asidi içeriği ile dikkat çekmektedir ki bu durum devekuşu etini yüksek besin değerine sahip, kaliteli ve diyete uygun gıda grubuna sokmaktadır. Bu kapsamda, m.gastrocnemius ve m.iliofibularis kasları arasındaki farklılıklar incelenmiştir. Nem içeriği m.gastrocnemius kasında m.iliofibularis kasına göre daha yüksek iken (p<0.05), yağ içeriği m. iliofibularis kasında daha yüksek bulunmuştur (p<0.05). Duyusal değerlendirme sonuçları bakımından m. iliofibularis kası m.gastrocnemius’a göre daha yüksek puanlar almıştır (p<0.05)(aroma ve tekstür parametrelerinde). Toplam doymuş yağ asitlerinde m. iliofibularis kası m. gastrocnemius den daha yüksek değerlere sahip iken; toplam tekli doymamış yağ asitleri, toplam çoklu doymamış yağ asitleri ve toplam doymamş yağ asitleri açısından daha düşük değerlere sahip olduğu tespit edilmiştir (p<0.05). İlave olarak, magnezyum ve bakır içeriği m. gastrocnemius kasında; çinko ve krom içeriği ise m. iliofibularis kasında daha yüksek bulunmuştur.

Anahtar Sözcükler: Devekuşu eti, besinsel özellik, m. gastrocnemius, m. iliofibularis

Bu makaleye atıf yapmak için Özsaraç, N., Kolsarıcı, N., Demirok, E., “Devekuşu Etinin Besinsel Özellikleri Üzerine Bir Araştırma” Gıda Teknolojileri Elektronik Dergisi, 2013, 8(1)63-68 How to cite this article Özsaraç, N., Kolsarıcı, N., Demirok, E., “A Study on Nutritional Characteristics of Ostrich Meat” Electronic Journal of Food Technologies, 2013,87(1)63-68

Teknolojik Araştırmalar: GTED 2013 (8) 63-68

A Study on Nutritional Characteristics of Ostrich Meat

1. INTRODUCTION As in the whole world, inadequate and unbalanced nutrition has great significance in our country and increases day by day. In order to satisfy the need of animal protein despite increasing population, countries have to look for different protein sources for diversifying animal products [1]. Increasing educational level of consumers and their satiety for ordinary animal products have led many breeders to different production sources such as ostrich [2].

The disadvantages concerning health caused by excessive animal fat consumption in developed countries with high purchase power and product range provided in chicken and turkey meat have reduced red meat consumption. Ostrich meat is characterised, relatively to meat from other species, by low intramuscular lipid content, favourable fatty acids profile (PUFA/SFA and n-6/n-3 ratios), low sodium (Na) content, and high iron, selenium, zinc content. Although numerous studies on the cholesterol content and fatty acid composition of ostrich meat have been conducted [3,4,5] little is known on differences of nutrient composition between muscles. When today’s tendency towards healthy and light food is taken into consideration, ostrich meat can be accounted as the ideal meat type for all of its characteristics which have been stated [6; 7; 8] .

Nowadays, the modern consumer wants to be sure of the nutrient composition of food that is bought for consumption. Unfortunately, until now the current knowledge of the nutritive value of this meat is still limited. Therefore, the present research was prepared in order to set to be providing an informational source for the foundations producing ostrich meat, of which consumption tends to increase in parallel with production in recent years, by determining its nutritional characteristics, helping consumers increase their awareness regarding the characteristics and the nutritional value of the meat and enlightening people who work in meat technology field on this matter.

2. MATERIALS AND METHODS Two different muscles (m. gastrocnemius, m. iliofiularis) from the ten ostriches, at the age of 14 months, were analyzed. They were stored at -20 ºC in laboratory of the Food Engineering Department in Engineering Faculty of Ankara University, Ankara, Turkey.

Moisture, protein, fat, ash assessment were determined by AOAC methods [9]. For pH determination, the sample (10 g) was homogenized in 100 ml of distilled water. The pH was measured with a pHmeter Orion 420 A (Orion Research-USA).

Lipit was extracted according to the method used by Gırolamı et al., [10]. Lipid extracts were transferred to test tubes for subsequent gas chromatographic analysis. Duplicates of 10 ml chloroform extract, corresponding to 100 mg of lipid, were methylated adding 1 ml of hexane and 0.05 ml of 2N methanolic KOH [10]. Gas chromatograph analysis was performed on a Agilent model GC-6400 (Germany) instrument equipped with a DB-23 capillary column (length 60 m, internal diameter 0.25 mm, film thickness 0.25 µm). Operating conditions were: a helium flow rate of 1 ml/min, a FID detector at 250 ºC, a split-splitless injector at 220ºC, injection volume of 0.5 ml. The individual fatty acid peaks were identified by comparison of retention times with those of known mixtures of standard fatty acids (FAME, Sigma;18912;1891;1896) run under the same operating conditions. Fatty acids were expressed as percent of total methylated fatty acids.

The determination of cholesterol was performed using the method of Rudel and Morris [12]. This method involves direct saponification of the samples, extraction of the unsaponifiable compounds with cyclohexane and read on a UV-Visible spectrophotometer (UNICAM UV\Vis, ABD). The content of cholesterol was expressed as mg/100 g of meat.

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Method of wet decomposition procedure was used to prepare the samples for mineral analysis and the mineral content determined by ICP-AES (Varian Vista Inductivelly Coupled Plasma Atomic Emission Spectrometer-Australia [13].

Sensory evaluation was performed on duplicate sample using a eight-member trained panel. The meat samples were thawed overnight at room temperature, taken out their package and boiled with water (1:1, v/v) during 1 hr. Subsequently, 2x2x2 cm samples were cut from the muscles and offered to the panelists.

Cooked samples were scored for colour, flavour, tenderness and overall acceptance using a 9-point scale (0: lowest intensity, 9: highest intensity) [14].

3. STATISTICAL ANALYSIS Results were analyzed using the paired-t test and sensory analysis were analyzed using the Wilcoxon Sign Test procedures of the Minitab (Minitab 13.0, 1995) statistical software [15].

4. RESULTS AND DISCUSSION Table 1 shows the results of the chemical analysis, cholesterol content and fatty acids profile of ostrich meat. Of particular interest is the low fat content, combined with high protein content of the ostrich muscles.

Neither the pH nor the protein content differed (p>0.05) in either the m. iliofibularis or m.gastrocnemius in between muscles. A similar range of values was found by Sales, and Hayes; Paleari et al., [4; 16]; whereas Hoffman and Fisher [17] reported lower contents of protein. Intramuscular fat and moisture content was different (p<0.05) between the m. iliofibularis and the m. gastrocnemius. The higher intramuscular fat content obtained for the m. iliofibularis. A similar range of values was found by Girolami et al., [10]. The intramuscular fat content is one of the most important factors influencing consumers’ choice with regards to meat type.

As also observed by Horbanczuk et al., [3] cholesterol content did not differ significantly among muscles (p>0.05). However, it can be considered comparable to the values previously reported for beef and chicken [18]. [19] and [20] stated that fat is the main source of cholesterol and that reduction in fat caused decrease in cholesterol content. Low cholesterol in meat depends on low intramuscular fat content. The studies also showed that the cholesterol content of ostrich meat is lower than those of many other animal species [16]. Cholesterol content is similar to that of beef and chicken meat (59 and 57 mg/100 g, respectively) [5]. Cholesterol content of ostrich meat has been reported as 57 mg/100 g tissue [21], 65-68 mg/100 g [3] and 83 mg/100 g [22].

The percentage of saturated, monounsaturated and polyunsaturated fatty acids showed different trends between muscles (p<0.05). The saturated C16:0; C17:0 monounsaturated C14:1; C16:1 and the polyunsaturated C20:2;C20:4 fatty acids were lower in the m.gastrocnemius than in the other muscle (p<0.05), whereas the amount of C24:0;C18:2 fatty acids were higher. As with turkey, bovine, [16] in our study a high percentage of C18:1 was found in all muscles. The highest percentage of total monounsaturated fatty acids were found in the m.gastrocnemius (46.5 %), followed by m. iliofibularis (44.31%) p<0.05. The percentage of polyunsaturated fatty acids differed significantly between muscles (p<0.05). The m.gastrocnemius showed a higher percentage (46.51;24.39;70.90%, respectively) of total monounsaturated, polyunsaturated and unsaturated and poliunsaturated fatty acids. Horbanczuk et al., [3] stated that polyunsaturated fatty acids (PUFA) rate among all fatty acids in ostrich meat was 30%, while Sales, [23] stated that it was 35,1%. In the research by Paul and Southgate [24], PUFA rate was determined to be 19% in chicken meat and 5% in beef. Moreover, among fatty acids, the amounts of C18:1 (oleic acid), C16:0 (palmitic acid) and C18:2 (linoleic acid) amounts were higher than the findings 65

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A Study on Nutritional Characteristics of Ostrich Meat

of many researchers [3; 10; 16] they are among the fatty acids which have the most frequent existence in ostrich meat Table 1. Chemical Parameters and Total Fatty Acid Content of Ostrich Meat M.gastrocnemius (n=10)

M. Iliofibularis (n=10)

pH

5.63±0.04

5.65±0.06

Moisture (%)

75.74±0.22 a

72.34±0.33b

Protein (%)

19.32±0.25

20.91±0.35

Fat (%)

1.80±0.17 a

2.71±0.74 b

Ash (%)

1.24±0.05

1.29±0.01

Cholesterol (mg/100g)

59.74±3.69

58.17±3.61

C12:0

0.05±0.00

0.05±0.00

C14:0

0.75±0.02

0.78±0.01

C15:0

0.24±0.01

0.23±0.01

C16:0

21.20±0.37b

23.93±0.26a

C17:0

0.22±0.01 b

0.25±0.01 a

C18:0

6.12±0.40

6.18±0.26

C24:0

0.21±0.03 a

0.07±0.01b

C14:1

0.12±0.01 a

0.08±0.00b

C16:1

8.35±0.65 a

6.30±0.50b

C17:1

0.22±0.01

0.19±0.01

C18:1

37.52±0.69

37.44±0.40

C20:1

0.30±0.01

0.30±0.01

C18:2

19.67±0.67 b

20.64±0.66 a

C18:3

1.22±0.06

1.21±0.05

C20:2

0.26±0.08 a

0.14±0.01b

C20:4

3.24±0.47 a

1.79±0.26 b

Total saturated

28.8±1.86 b

31.49±0.92 a

Total monounsaturated

46.51±4.09 a

44.31±2.4 b

Total polyunsaturated

24.39±2.58 a

23.78±2.12 b

Total unsaturated

70.90±1.91 a

68.09±1.22 b

Saturated/Unsaturated

0.41±0.03

0.46±0.06

Fatty Acids (%) Saturated

Monounsaturated

Polyunsaturated

a,b: Different letters within the columns indicate significant differences (p<0.05) (n=10)

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Table 2: Mineral Content of Ostrich Meat (mg/100 g)

Mineral

M.gastrocnemius (n=10)

M. Iliofibularis (n=10)

Potassium

366.0±12.0

371.7±7.0

Phosphorus

230.7±15.4

237.4±15.4

Magnesium

26.52±0.90

a

29.40±0.37 b

Iron

6.51±0.61

6.97±0.38

Zinc

5.36±0.37 a

2.72±0.31b

a,b: Different letters within the

columns indicate significant differences (p<0.05) (n=10)

Table 2. contains the mineral composition of the ostrich muscles. Of the major minerals determined magnesium and zinc were the highest (in that order) in the m.gastrocnemius (p<0.05). An important characteristic of ostrich meat is that its mineral content is greater in comparison to beef and chicken meat [4].

Meat in human diet is considered an important source of protein and minerals, especially iron and zinc.

Zinc levels of raw ostrich meat evaluated by Lombardi et al., [25] varied between different muscles as 3.1 mg/100g Results of the sensory evaluation are presented in Table 3. Flavour and tenderness are among the most important attributes infuencing customer choice and colour also plays a relevant role on the perception of quality of meat products. m.iliofibularis had the highest points in all parameters.

Table 3. Sensory Evaluation of Ostrich Meat m.gastrocnemius (n=10)

m.iliofibularis (n=10)

Flavour

5.55±0.11a

6.06±0.14 b

Tenderness

5.30±0.18a

6.03±0.22 b

Colour

6.00±0.08

6.19±0.14

Overall Acceptance

5.48±0.12

5.99±0.23

a,b: Different letters within the columns indicate significant differences (p<0,05) (n=10)

It can be concluded that this study contributes to a description of the nutritional composition of ostrich meat, obtained on different muscles, which could be use to extend existing information. In addition to its high protein content, ostrich meat contains low fat. This low intramuscular fat content makes ostrich meat more advantageous and plays an important role in the marketing strategy of ostrich meat when the significance of fat for health is taken into account. Moreover, if the recommendations regarding reducing saturated fatty acid content and preferring food containing high amounts of unsaturated fatty acids are taken into consideration, ostrich meat will be a promising product in this respect. In order to establish a database on the nutrient composition on ostrich meat for further use in research on human consumption of this relative unknown type of meat.

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