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Subject: Entomology × Author: Bhattacharjee, Snigdha × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    NUTRITIONAL PROFILING OF SOME EDIBLE ORTHOPTERAN INSECTS
    (AAU, Jorhat, 2021) Bhattacharjee, Snigdha; Bhattacharyya, Badal
    Laboratory experiments were carried out to assess the nutritive value of four edible orthopteran insect species viz., field cricket (Brachytrupes portentosus), mole cricket (Gryllotalpa africana), rice grasshopper (Oxya sp.) and cone headed grasshopper (Ruspolia nitidula) based on their proximate & elemental content, amino & fatty acid profiles, antioxidant & anti-nutritional properties as well as their microbial aspects in the Soil Arthropod Pests Laboratory, Department of Entomology; Post Graduate Laboratory, Department of Biochemistry & Agricultural Chemistry and Soil Biodiversity- Biofertilizers Laboratory, Department of Soil Science, Assam Agricultural University, Jorhat during 2017-2020. Proximate analysis of all the four edible insect species revealed that the moisture content ranged from 2.559-7.537 per cent. Perusal of data showed that the highest mean percentage of moisture content was recorded in B. portentosus (7.537%) whereas R. nitidula registered the least moisture content (2.559%) which makes the insect powder preferably suitable to be preserved for a reasonable period of time without the risk of any microbial deterioration. The carbohydrate content of the studied species varied widely and ranged from 5.138-24.219 per cent where the maximum (24.219%) was registered in Oxya sp. and the lowest (5.138%) was recorded in B. portentosus. Appreciable amount of crude protein content was estimated in all the studied species which ranged from 45.892-69.591 per cent. The highest (69.591%) crude protein was registered in Oxya sp. and it was found to be significantly superior over rest of the species. The protein content recorded in G. africana, B. portentosus and R. nitidula were 67.884, 53.096 and 45.892 per cent, respectively. Crude fat content registered in the studied species varied significantly and was ranged from 8.478-37.619 per cent. The highest (37.619%) crude fat content was recorded in R. nitidula followed by B. portentosus (25.347%) and Oxya sp. (10.773%) whereas G. africana recorded the lowest (8.478%) amount of crude fat content. The crude fibre content varied from 2.899-9.138 per cent and Oxya sp. registered significantly high amount of crude fibre (9.138%) content followed by B. portentosus (8.409%) and G. africana (7.553%). The highest (5.958%) ash content was recorded in B. portentosus which showed statistical parity with G. africana (5.686%) whereas the lowest (1.642%) was recorded in case of R. nitidula. While analyzing the energy content (kcal/100g) of all the four species, the maximum energy content (573.371) was estimated in R. nitidula followed by Oxya sp. (472.197) and B. portentosus (461.059) whereas, G. africana recorded the lowest energy content of 374.330 kcal/100g. 6 Altogether 8 minerals as elemental composition were estimated in all the studied species. The mineral analysis indicated that the concentration of macro elements viz., K and Ca were significantly higher (58.868 & 29.765, mg/100g, respectively) in B. portentosus except for Na and Mg (35.694 & 20.319 mg/100g) whereas the lowest amount (49.573, 8.188, 17.105 and 29.549 mg/100g, respectively) was recorded in R. nitidula. Considerable amount of four micro elements were also recorded in all the studied species. The Fe content estimated in the studied species ranged from 12.231- 53.280 mg/100g where G. africana registered the highest Fe content (53.280 mg/100g) which was significantly superior over rest of the species. Zn content (mg/100g) was estimated to be the highest (15.423) in G. africana which showed statistical parity with B. portentosus (15.295) whereas significantly superior over Oxya sp. (12.950) and R. nitidula (7.848). Mn and Cu content of all the species were found comparatively in trace amounts which ranged from 0.866-6.579 mg/100g and 0.566-3.348 mg/100g, respectively. Perusal of data as regards to the amino acid composition of all the four edible species indicated the availability of 18 common amino acids, out of which 8 were essential. Among all the amino acids quantified, glutamic acid was found to be the most abundant (7.87-5.14%) in all the four species. Alanine, leucine, aspartic acid and valine were the other amino acids available in appreciable amount with values ranging from 7.21-4.86, 5.11-3.89, 4.78-3.47 and 4.18-2.83 per cent, respectively. The percentage of savory amino acids (i.e. glutamate & aspartic acid) was estimated to be highest in B. portentosus (7.87 & 4.78%) followed by Oxya sp. (7.69 & 4.62%) and G. africana (7.28 & 3.85%), respectively. In case of sweet amino acids (i.e. alanine & glycine), the highest amount was recorded in Oxya sp. (7.70 & 3.93%) followed by B. portentosus (7.21 & 3.42%) and G. africana (5.90 & 3.26%), respectively. Relatively trace amount (0.69-1.14 and 0.10-0.25%) of total sulphur containing amino acids (methionine and cysteine) were quantified in all studied edible insects, respectively. The total fatty acid analysis of all the four species revealed that the highest (13.22, 25.31 and 2.47%) amount of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) were recorded in R. nitidula followed by B. portentosus (9.61% SFA, 10.56 % MUFA and 8.13 % PUFA) and G. africana (5.45 % SFA, 7.18 % MUFA and 4.82 % PUFA). Quantification of the fatty acid profile revealed that palmitic acid was the most predominant fatty acid in all the studied species and was recorded to be highest in R. nitidula (11.35%) followed by B. portentosus (7.14%) and G. africana (3.60%) whereas the least (1.55%) amount was recorded in Oxya sp. The findings also revealed the presence of one essential omega 6 7 fatty acid i.e. linoleic acid (1.65%) in Oxya sp. The rest of the fatty acids were recorded in relatively trace amounts in all the studied insect species. The rest of the fatty acids were recorded in trace amount in all the studied insect species. As antioxidants, phenol and flavonoid contents of all the studied edible insect species was estimated and the data found to be varied from 1.062-4.467 mg catechol equivalent/g and 2.412-4.470 mg quercetin equivalent/g, respectively. Oxya sp. registered the highest (4.467 mg catechol equivalent/g) phenol content and was found to be significantly superior over rest of the species. The highest flavonoid content (4.470 mg quercetin equivalent/g) was also registered in Oxya sp. followed by B. portentosus (3.071 mg quercetin equivalent/g) and G. africana (2.799 mg quercetin equivalent/g). Tannin, phytic acid and oxalic acid contents were also estimated as antinutritional factors and were recorded within the permissible limit (250-500 mg/100g). The concentration of phytic acid and tannin were ranged from 26.620-122.427 mg/100g and 97.823-210.500 mg tannic acid equivalent/100g, respectively. The oxalic acid recorded in case of B. portentosus, G. africana, Oxya sp. and R. nitidula were 3.542, 2.910, 3.530 and 3.795 mg/100g, respectively. Investigations on the microbial aspects of insect powders revealed that the Total Viable Counts (TVC) were higher in the samples stored under ambient temperature (9.06-9.29 log cfu/g) as compared to the samples stored under refrigerated temperature (7.33-7.66 log cfu/g). Perusal of data showed that the obtained values exceeded the guideline values for minced meat (i.e. between 5.7-6.7 log cfu/g), however, microbial enumerations of powdered insect samples after 15 days of storage showed that all the samples were free of any yeast and mould contaminations. Biochemical test kits further confirmed the absence of two common food borne pathogens i.e. Escherichia coli and Salmonella sp. in all the studied insect samples.