Proximate and heavy metal analysis of five instant noodles samples was carried out using standard analytical methods. The proximate analysis showed the presence of moisture content (3.65% - 7.80%), ash content (1.11% - 5.50%), fat content (13.64% - 18.69%), crude protein content (0.167% - 0.202%), crude fibre content (1.00% - 9.25%) and carbohydrate content (63.68% - 79.72%). All essential elements (Fe and Zn) investigated in the noodle samples occurred within the threshold limit of WHO, (2003) standard (10.00 - 50.00 mg/kg and 5.000 - 22.000 mg/kg) while the heavy metals (Cd, Cr, Mn, Ni and Pd) in some samples occurred at levels relatively above the minimum tolerable limit of WHO, (2003). Hence, caution should be taken in the successive consumption of these noodles to avoid diseases associated with the over time accumulation of these heavy metals especially in samples where they appeared in relatively high amount.
Wheat flour noodles are staple foods in many Asian countries. Historically speaking, noodles originated from Northern China and subsequently introduced to other Asian Countries by traders, seafarers and migrants. Noodles have now become more widely adopted for everyday use and its storage has been facilitated by the introduction of dried noodles. Technological innovation has also been applied to enhance noodles quality and adaptation to meet up with consumer demands and also increase the taste of boiled noodles. Instant noodles known as staple food in Malaysia lack some nutritional components such as dietary intake fibre in appropriate proportion, therefore incorporation of lentil on noodles gives additional properties like increase in fibre content and indirectly contributes to protein and mineral content. Noodles are widely consumed throughout the world and their global consumption is second only to bread; it is a fast growing sector of the pasta industry. This is because instant noodles are convenient, easy to cook, low cost and have relatively long shelf-life. Wheat flour which is usually used to make instant noodles is not only low in fibre and protein content but also poor in essential amino acid; lysine. Flour of hard wheat (Tritium aestivuml) is the main primary ingredient [
Considering the above mentioned menace and others, efforts such as this work geared towards the determination of the dietary intake and heavy metals content of consumer foods such as instant noodles with a view to determining potential toxic agents should be encouraged.
The five noodles samples were bought from Eke Awka market, Awka, Anambra State, Nigeria. The samples were as follows-Indomie instant noodles, Tummy-Tummy instant noodles, Honey well instant noodles, Dangote instant noodles and Golden penny instant noodles. All the samples were in 120 g packets.
The proximate analysis which is the partitioning of the samples into six categories (Moisture content, Ash Content, Crude protein(kjedahl protein), Crude lipids, Crude fibre and Carbohydrates (Nitrogen free extracts)) based on their chemical properties were done using standard analytical procedures [
Using Atomic Absorption Spectrophotometer model varian AA 280, trace metal level of the samples were determined. Examined trace metals included Cd, Cr, Fe, Mn, Ni, Pd, and Zn [
The results of the proximate analysis of the selected noodles samples are given in
The relative low amount of moisture content in these noodles is in line with the common knowledge that the
Noodle Code | Noodle’s Name | Moisture Content (%) | Ash Content (%) | Fat Content (%) | Crude Protein (%) | Crude Fibre (%) | Carbohydrate (%) |
---|---|---|---|---|---|---|---|
V | Dangote | 5.60 | 5.50 | 15.80 | 0.167 | 9.25 | 63.68 |
W | Tummy-Tummy | 7.80 | 1.60 | 18.61 | 0.202 | 3.90 | 67.88 |
X | Indomie | 3.65 | 1.80 | 13.64 | 0.176 | 1.00 | 79.71 |
Y | Honey-Well | 6.60 | 1.50 | 18.44 | 0.211 | 3.00 | 70.30 |
Z | Golden Penny | 5.15 | 1.11 | 18.69 | 0.185 | 5.85 | 69.02 |
higher the moisture content of a food sample, the lower its shelf life because of its high susceptibility to bacterial attack. Hence, these noodles which are expected to have at least a year between date of manufacture and expira- tion are left with as little moisture as possible to limit rate of bacterial attack.
The Ash content of these selected noodles ranged between 1.11% (Sample Z) to 5.50 (sample V). This showed that sample V (Dangote noodles) had a higher mineral content as the ash content of a food sample gives an insight into the inorganic (mineral) content of the sample.
The fat content of these samples ranged between 13.64% (Sample X) to 18.69% (Sample Z). The implication of this was that the sample that had more fat had more energy than the one that had less fat, however this might pose a health risk as frequent consumption of these noodles as witnessed today would lead to the development of more fatty acid in the adipose tissue and would contribute to the cholesterol level in humans with their asso- ciated health implications such as obesity and the risk of heart disease.
The low protein content (0.167% - 0.202%) of these noodle samples showed their deficiency in supplying adequate amount of dietary protein needed for growth and development especially in children. Therefore, cau- tion should be taken in the over dependence on noodles or other protein sources such as egg, meat, fish etc could be incorporated while serving these noodles in other to augment this noted deficiency.
Crude fibre content of these noodles which range between 1.00% - 9.25% on its own is perceived to be of acceptable level as crude fibres are not of definite or unique nutritive benefits but simply helped in the bowel movement. The level of crude fibre in all these samples could be seen as permissible.
The high carbohydrate content with the range of between 63.68% to 79.71% are in consonance with expected results as these noodles are usually sources of energy given the raw material for their production (wheat flour) according to Hou and Kruk, 1998 [
The overall observation on the heavy metal level of these selected noodles as in
These little variations observed in the Proximate and most especially the Heavy metal compositions of the selected noodles samples, might not pose any immediate serious health effect given their accumulation in the human body but long time accumulation of these metals could lead to health issues.
It is therefore recommended that manufacturers of these noodles review the sources of these heavy metals which
Noodle Code | Noodle’s Name | Cr (mg/kg) | Cd (mg/kg) | Fe (mg/kg) | Mn (mg/kg) | Ni (mg/kg) | Pb (mg/kg) | Zn (mg/kg) |
---|---|---|---|---|---|---|---|---|
V | Dangote | 0.063 | 0.005 | 1.625 | 0.135 | 0.010 | 0.029 | 1.797 |
W | Tummy-Tummy | 0.084 | 0.003 | 3.086 | 0.157 | 0.028 | 0.064 | 1.358 |
X | Indomie | 0.097 | 0.005 | 1.343 | 0.115 | 0.013 | 0.026 | 1.482 |
Y | Honey-Well | 0.079 | 0.001 | 1.079 | 0.112 | 0.007 | 0.025 | 0.359 |
Z | Golden Penny | 0.118 | 0.008 | 1.550 | 0.097 | 0.004 | 0.106 | 0.973 |
WHO Standard | 0.050 | 0.003 | 10.000 - 50.000 | NA | NA | 0.025 | 5.000 - 22.000 |
NA = not available.
could be from the water they use or their machineries with a view to reducing them further to permissible levels. The protein content of these noodles should also be improved in order to be able to fairly supply the required daily allowance.