Chemical Composition and Nutritional Evaluation of the Seeds of Suaeda salsa (L.) Pall

Chaofeng Li, Boping Tang, Senhao Jiang

Journal of Food and Nutrition Research

Chemical Composition and Nutritional Evaluation of the Seeds of Suaeda salsa (L.) Pall

Chaofeng Li1,, Boping Tang1, 2, Senhao Jiang1, 2

1Jiangsu Provincial Key Laboratory of Beach Bioresources and Environmental Protection, Yancheng Teachers University, Yancheng, China

2Jiangsu Provincial Key Laboratory of Bioresources of Saline Solis, Yancheng Teachers University, Yancheng, China

Abstract

Chemical composition and nutritional evaluation of the seed of Suaeda salsa were studied. The results indicated that seeds contained 5.35% moisture, 4.76% ash, 25.68% fat, 15.27% fiber, 27.32% protein and 20.11% carbohydrates. Sodium was the predominant element followed by potassium and then calcium. Vitamin C and vitamin E were detected. The amino acid profile compared good with FAO/WHO recommended pattern except for cystine/methionine, isoleucine, tyrosine/phenylalanine and tryptophane. Also, the first limiting amino acid was cystine/methionine. Fatty acid composition showed that linoleic acid was the major fatty acid, followed by oleic acid, palmitic acid, linolenic acid, stearic acid and palmitoleic acid. S. salsa seed was a kind of oil source that could satisfy the standards of modern nutrition towards healthy food and it possesses the development and utilization values.

Cite this article:

  • Chaofeng Li, Boping Tang, Senhao Jiang. Chemical Composition and Nutritional Evaluation of the Seeds of Suaeda salsa (L.) Pall. Journal of Food and Nutrition Research. Vol. 5, No. 1, 2017, pp 22-26. http://pubs.sciepub.com/jfnr/5/1/4
  • Li, Chaofeng, Boping Tang, and Senhao Jiang. "Chemical Composition and Nutritional Evaluation of the Seeds of Suaeda salsa (L.) Pall." Journal of Food and Nutrition Research 5.1 (2017): 22-26.
  • Li, C. , Tang, B. , & Jiang, S. (2017). Chemical Composition and Nutritional Evaluation of the Seeds of Suaeda salsa (L.) Pall. Journal of Food and Nutrition Research, 5(1), 22-26.
  • Li, Chaofeng, Boping Tang, and Senhao Jiang. "Chemical Composition and Nutritional Evaluation of the Seeds of Suaeda salsa (L.) Pall." Journal of Food and Nutrition Research 5, no. 1 (2017): 22-26.

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1. Introduction

Population explosion, land degradation, resource short and environmental pollution have attracted wide concerns and worries. Soil compaction and pollution were the worldwide problem of resources and ecology, has become the biggest obstacle to restricting the agricultural production, and then threatened the human survival.

Suaeda salsa (L.) Pall is an annual herb and euhalophyte [1], which occurs both on saline soil and in the intertidal zone [1], and the typical halophyte growing in soil which is higher than 2% in salt [2]. S. salsa was the most luxuriant in the humid soil which was 1% in salt and usually formed the single dominant plant community [2]. S. salsa showed the salt-tolerance ability, and then could effectively reduce salt content, increase soil organic matter and improve N, P, K in soil surface. Therefore, S. salsa, which could improve saline soil, was the preferred plant improving saline alkali soil and could obtain good economic, ecological and social benefits [2, 3].

The fresh branches of S. salsa were a highly valuable vegetable and its seeds could produce an edible oil, especially for the Chinese peasants in a time of serious famine [4]. Also, S. salsa was frequently used as medicine to treating fever, food retention, blood sugar and pressure, expanding blood vessel, preventing cardiovascular system diseases and improving body immunity [5]. In addition, the seed of S. salsa was an important food source for animals and recognized as the economic potential resource due to the high amount of protein and crude fiber [5]. Therefore, this study investigated the chemical composition and nutritive value of S. salsa seed. This study would provide information on whether or not advisable to incorporate this seed into the oil source and the feed additives.

2. Material and Methods

Dry mature seeds of S. salsa were collected from coastal beach in Dafeng district, Yancheng city, Jiangsu Province. Seeds were ground using an electric mill then used for chemical composition analyses. The coarsely ground seeds were passed through a 0.25 mm sieve to obtain the flour which will be used for chemical composition determination. N-Hexane was of chromatographic grade and purchased from Fisher Scientific. Linoleic Acid was of chromatographic grade and purchased from Sigma-Aldrich Co. (St. Louis, Mo., USA). All the other chemicals and reagents used in this study were of analytical grade and purchased from China.

2.1. Proximate Analysis

Proximate composition of the S. salsa seeds power was determined by using the standard Association of Official Analytical Chemists procedures [6]. Moisture content was evaluated by the loss of weight upon drying in an oven at 100°C to a constant weight. Ash was assessed by incineration at 550°C of known weights of the samples in a muffle furnace (Method No. 930.05). Crude fat was found out by exhaustively extracting a known weight of sample in petroleum ether (boiling point, 30-60°C) in a Soxhlet extractor (Method No. 930.09). Protein amount (N× 6.25) was measured by the Kjeldahl method (Method No. 978.04). Crude fiber quantity was ascertained after digesting a known weight of fat-free sample in refluxing 1.25% sulfuric acid and 1.25% sodium hydroxide (Method No.930.10). Carbohydrates were calculated by difference.

2.2. Vitamins Analysis

The vitamin C and vitamin E were determined by the methods of Li, et al [7] and Yang, et al [8] with some modifications.

S. salsa seeds power (1.00 g) was mixed with 80 mL 25 mmol/L metaphosphoric acid at an ice bath, extracted by ultrasonic at 400 W for 30 min, centrifuged at 15000 rpm for 10 min at 4°C. The supernatant was made up to 100 mL by 25 mmol/L metaphosphoric acid, and then filtered by 0.22 μm membrane and stored with airtight and light-free. Vitamin C was performed using an Ultimate 3000, equipped with a UV detector and a column, Diamonsil C18 (250 mm × 4.6 mm, 5 μm); The mobile phase was 0.005 mol/L sodium ethanesulphonate (pH 3.2) - methanol (7:3, v/v). The flow rate was 1.0 mL/min. The injection volume was 10 μL. The detection wavelength was 254 nm and the column temperature was 30°C.

S. salsa seeds power (1.00 g) was mixed with absolute alcohol at room temperature, extracted by ultrasonic at 400 W for 20 min, centrifuged (15000 rpm, 10 min, 4°C) at 15000 rpm for 10 min. The supernatant was made up to 50 mL by absolute alcohol, and then filtered by 0.22 μm membrane. Vitamin E was performed using an Ultimate 3000, equipped with a UV detector and a column, Diamonsil C18 (250 mm × 4.6 mm, 5 μm); The mobile phase was methanol. The flow rate was 1.0 mL/min. The injection volume was 10 μL. The detection wavelength was 275 nm and the column temperature was 35°C.

2.3. Minerals Analysis

The analysis of mineral elements was performed according to the method of Xie, et al [9] with some modifications. Briefly, approximately 1.00 g of S. salsa seeds power was digested by dry incineration in porcelain containers by adding 10 mL of concentrated HNO3 (10% solution, w/v). The mixture was first maintained over a hot plate until dryness and then in muffle furnace at 450-500°C for 16 h. The incinerated sample was then treated with 1 mL of concentrated HNO3 for ash whitening and this mixture was digested again for 6 h. Then, the residue was dissolved in 5 mL of 10% (v/v) HNO3 and filtered through a filter paper. The sample was diluted to 25 mL with ultra pure water. Blank solutions were prepared in the same way as the S. salsa seeds samples. The contents of the elements were determined by an inductively coupled plasma atomic absorption spectrometer (FEI, Quanta 200) with axial viewing of the emitted radiation. The flow rate of sample uptake was 1.5 mL/min. Operating parameters for the instrument included forward power 1300 W, coolant gas flow rate 15.0 L/min, auxiliary gas flow rate 0.2 L/min and nebulizer gas flow rate 0.9 L/min.

2.4. Amino Acids Analysis

Amino acids were determined by HPLC (Thermo-Fisher, Ultimate 3000, USA) according to the method of Yang, et al [10]. The S. salsa seeds power (1.00 g) was hydrolyzed with 5 mL of 6 mol/L HCl or 4.2 mol/L NaOH in a sealed tube at 110°C in an oven for 24 h. The hydrolyzed sample was made up to 50 mL and filtered using a 0.45 μm membrane filter. Sample solution (200 µL) was completely mixed with 10 µL 0.5 g/L leucine, 100 µL 0.1 mol/L isothiocyanate phenyl - acetonitrile solution, 100 µL 1 mol/L triethylamine - acetonitrile solution, and then placed at room temperature for 1 h, added 400µL n-hexane. Vibrated for 1 min, the mixture was placed for 10 min. The lower solution was absorbed by the syringe and filtered by 0.45 μm membrane filter.

Chromatographic conditions: Amino acids analysis were performed using an Ultimate 3000, equipped with a UV detector and a column, Venusil XBA-AA column (250 mm × 4.6 mm, 5 μm); The mobile phase was consisted of solvents A (0.1mol/L sodium acetate -acetonitrile 97:3, v/v) and solvent B (acetonitrile - ultra pure water 4:1, v/v). The elution was performed as a linear gradient as follows: 0 min, 0% B; 13 min, 7% B; 23 min, 23% B; 29 min, 35% B; 35 min, 40% B; 40 min, 100% B; 45 min, 100% B; 47 min, 0% B; The column temperature was 40°C. The quantification of analysis was performed by UV detector at 254 nm. The injection volume was 2 μL. The flow rate was 1.0 mL/min.

2.5. Fatty Acids Analysis

Accurately weighed 200 mg S. salsa seeds power, added 2 mL 1mol/L KOH/methanol solution to saponify for 10 min at 70°C water bath and then cooled down, added 3 mL 1mol/L boron trifluoride/methanol solution to methyl esterification for 10 min at 70°C water bath. After cooling down, accurately added 0.5 mL n-hexane and the supernatant of organic phase was determined by gas chromatography (Agilent 7890B) according to the method of Liang, et al [11]. Fatty acids analysis was performed using a Gas Chromatograph (GC-17A), equipped with a flame ionization detector and a column, HP-88, (100 m, 0.25mm i.d. x 0.2 µm). The column temperature was programmed from 70°C for 1 min then elevated to 280°C at a rate of 25°C /min and hold at 280°C for 10 min. All the injector and detector temperatures were 250°C. Nitrogen was the carrier gas at a flow rate of 1.5 mL/min.

2.6. Statistical Analysis

All the analyses were performed in triplicate. Data were expressed as mean ± standard deviation (SD). Statistical analysis was done using Microsoft office excel 2007.

3. Results

3.1. Proximate Composition

The results presented in Table 1 showed that the moisture content of S. salsa seeds was low (53.57 g/Kg) indicating excellent storing quality for this seeds. Ash content of S. salsa seeds was 47.61 g/Kg. The crude fat yield (256.89 g/Kg) was higher than that reported for soybean, and basically equal in Oenothera biennis L. which was health care oil widely concerned by the world [12]. The relatively high level of crude fat in S. salsa seeds indicated that the seeds would be a good source of energy. The content of crude fiber was 152.75 g/Kg. Therefore, S. salsa seeds could be considered as a good source for dietary fiber. In fact, the dietary fiber had an important role in the human nutrition in that fiber helped to maintain the health of the gastrointestinal tract, but in excess may bind trace elements, leading to deficiencies of iron and zinc [13].

The results showed that S. salsa seeds contained the abundant protein (273.20 g/Kg). These results indicated that S. salsa seeds could be included in food formulations as a source of protein. Regarding the carbohydrate content, S. salsa seeds contained 201.18 g/Kg carbohydrate. This level of the carbohydrate was low, due to the higher levels of crude protein, crude fat and fiber in the seed. Therefore, the chemical composition of S. salsa seeds was determined to be nutritious and incorporating this seeds into the human diets would improve the nutrition status.

3.2. Minerals

Plants were known to provide the required minerals important for human health. Table 1 showed the minerals composition of S. salsa seeds. Sodium was the predominant mineral, the other elements in descending order by quantity were K, Ca, P, Fe, Zn, Mn, Cu and Se. Based on the above results, S. salsa seeds were a good source for minerals, especially Na, K, Ca, P, Fe and Zn. Specially, Se was abundant in S. salsa seeds. Since some flours used in commercial feed for livestock were deficient in one or more element and protein, addition of S. salsa seeds flour might improve their nutritional properties. Moreover, S. salsa could be used as the material of plant salt extraction.

3.3. Vitamins

Vitamins were important indexes for evaluation of nutritive value and essential to human health. In this paper, fat-soluble vitamin E and water-soluble vitamin C were determined. Results were shown in Table1. As the results showed vitamin E was richer than the water-soluble vitamin C in S. salsa seeds and the content reached 2000 mg/Kg.

Table 1. The Proximate Composition of S. salsa Seeds

3.4. Amino Acids

The amino acid profile and essential amino acid score (AAS) for S. salsa seeds were listed in Table 2 and Table 3. The potential food value of the seeds proteins (as a source of amino acids) could be justified by comparison with the FAO reference pattern [14]. In S. salsa seeds, the essential amino acids/total amino acids (EAA/TAA) was 0.36 and the essential amino acids/non-essential amino acids (EAA/NEAA) was 0.56. According with the ideal model recommended by FAO/WHO, the quality of protein was excellent when EAA/TAA was about 0.40 and EAA/NEAA was more than 0.60. Therefore, the S. salsa seeds were a good source of protein and used as the feed for livestock.

The amino acid profile of S. salsa seeds revealed that both threonine and tryptophan had higher levels than those listed in FAO/WHO reference pattern. Also, the level of valine and lysine were very similar to that of the FAO/WHO reference pattern. However, the other essential amino acids had lower levels when compared with those of the FAO/WHO reference pattern. Moreover, the result of AAS indicated that the most limiting amino acids were cystine/methionine (0.34) and isoleucine (0.56).

Table 2. Amino Acids Composition of S. salsa Seeds

Table 3. AAS and CS in the protein from S. salsa seeds

3.5. Fatty Acids

The fatty acid profile of S. salsa seeds was shown in Table 4. Linoleic acid was the predominant fatty acid (1769.47 mg/Kg), followed by oleic acid (355.84 mg/Kg), palmitic acid (193.54 mg/Kg), linolenic acid (114.94 mg/Kg), stearic acid (50.43 mg/Kg) and palmitoleic acid (49.92 mg/Kg). These results indicated that linoleic acid in S. salsa seeds was richer than that of Perilla frutescens seeds and slightly less than those of O. biennis seeds and Carthamus tinctorius seeds. Also, the results of S. salsa seeds indicated that the seeds had relatively high levels of the essential fatty acid, linoleic acid, followed by oleic, palmitic and linolenic acid. The unsaturated fatty acids in S. salsa seeds were 2290.18 mg/Kg and more abundant than that of O. biennis seeds. Moreover, the higher index of mono- and polyunsaturated fatty acids would play an important role in human and animal health, and then the linoleic acid could play a significant role in reducing blood cholesterol levels when consumed regularly as a part of the diet [15]. Therefore, S. salsa seeds could be used as the material producing unsaturated fatty acids and linoleic acid. And then these indicated that the oil was highly nutritious.

Table 4. Fatty acids composition of S. salsa seeds

4. Discussion

In all the oil crops, soybean was one of the most important oil plants in the world. In soybean, the fat content was above 20%, which was similar with that of S. salsa seeds and a bit less than that of S. salsa seeds. However, S. salsa usually grew in the desert, wasteland, beach, and so on, did not occupy the cultivated land and need to manage, and then naturally grew and died. Therefore, S. salsa had the high value of development in oil source, which should be taken enough attention, especially in the case of desertification, salinization, and deforestation. Furthermore, when S. salsa was cultivated and grown in the soil salinity of 0.23% ~ 0.98%, the yield of S. salsa seeds might been increased by 1 or 2 times [16].

In the nutrition evaluation of fatty acids, PUFA/SAF was an important index. When the ratio of PUFA/SAF was more than 2, the fat might reduce blood lipids. Moreover, the greater the ratio was, the stronger the ability to reduce blood lipids was. The PUFA/SAF ratio was 7.72 and much more than 2 in the fatty acids of S. salsa seeds, so S. salsa seeds oil, which was used as health edible oil, had the high valve. Because of the abundant nutrition, Oenothera biennis and Perilla frutescens had been become the oil plants, and the linoleic acid was 73.5% ~ 81.9% [17] and 10.43% ~ 16.65% [18], respectively. In S. salsa seeds oil, the linoleic acid was far richer than that of Perilla frutescens, and was similar with that of Oenothera biennis and Carthamus tinctorius L.. Therefore, S. salsa seeds oil could meet the need of the market and the development value, and could be used as the high quality and cheap material for synthesizing conjugated linoleic acid which had the function of anti-cancer, anti-cardiovascular diseases, and participated in lipolysis, metabolism and other physiological activity.

S. salsa was a kind of halophyte accumulating salt in vivo, and then could desalinate, reduce soil salinity, increase nitrogen, phosphorus, potassium, organic matter, microbial in soils, and so on, thereby improve the soil quality[19]. S. salsa was conducive to saline environment and vegetation restoration, could eliminate the bare salt and alkali wasteland, prevent soil erosion, protect wetlands [20]. S. salsa was very developed in root and one of an excellent sand fixing plants, could prevent the desert migration [21]. Thus, the development S. salsa had also the good ecological effect and meet the requirement for environmental improvement.

5. Conclusions

The present study on the chemical composition of S. salsa seeds suggested that these seeds could be useful as a new source of edible oil especially for health care and a favorable livestock feed for adding protein, and so on.

Acknowledgements

We are grateful for financial support from Jiangsu Province Natural Science Research Foundation, No. BK20150422 and Jiangsu Provincial Key Laboratory of Coastal wetland Bioresources and Environmental protection open Foundation, No. JKCBE2012027.

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