Physical, nutritional, functional and rehydration properties of palm beetle (Oryctes rhynoceros) larvae as affected by drying and roasting

doi:10.21203/rs.3.rs-3316222/v1

The effects of sun-drying, oven-drying and roasting on physical, chemical, functional and rehydration properties of palm beetle (Oryctes rhinoceros L.) larvae were investigated. Average weight (18.64g), length (67.74mm), breadth (22.56mm), and thickness (19.12mm) of live larvae reduced to 2.85-3.86mm, 36.78-38.24mm, 20.10-21.05mm and 16.50-18.88mm, respectively, with degutting, drying and roasting. Generally, lightness (49.93) and yellowness (11.68) of live larvae reduced to 28.89 and 5.60, when sun-dried. Crude protein, ash, fat and crude fibre contents of processed larvae varied from 65.46–69.99, 9.75–10.27. 13.79–21.01 and 0.55-1.23g/100g, respectively. Potassium, magnesium and sodium contents of processed larvae varied from 212.6–379.1, 58.76–184.6, and 104.65–170.75mg/100g, respectively. Sun-dried larvae showed higher amino acids contents than oven-dried and roasted larvae. However, the processed beetle larvae were rich in leucine, lysine, phenylalanine, aspartic acid, glutamic acid, isoleucine, leucine, threonine, valine, arginine, histidine and tyrosine. The water and absorption, OAC, loose and packed bulk density and dispersibility varied between 1.77–2.03, 1.20–1.33, 0.38-0.41g/mL, 0.56-0.60g/mL, 15.15-24.67sec and 18.77-26.00sec, respectively. Moisture contents of rehydrated sun-dried larvae were higher than oven-dried and roasted larvae between 15-45^oC.

Palm beetle larvae

Oryctes rhinoceros

Drying

Roasting

Nutritional properties

Rehydration characteristics

Protein deficiency remains a major problem worldwide and, with an estimated population projection of 9.7 billion by the year 2050, and this dilemma of malnutrition may worsen if a cheaper and sustainable protein source is not urgently provided (van Huis, 2015; Gahukar, 2011). Animal and plant protein costs remain prohibitively high, with the attendant production challenges. In order to mitigate malnutrition and meet the protein requirement of these growing young populations, entomophagy which refers to consumption of insects and their products, remains a cheaper and sustainable alternative source. Most edible insects have almost the same or higher proportion of proteins, fat and energy value, and can effectively serve as a substitute to meat and fish, with lower impact on the environment (Tang et al., 2019; van Huis, 2013), and higher production yield. Moreover, insects are also rich in vitamins as well as mineral salts, especially iron and calcium (Tang et al., 2019).

Insects are consumed in their various developmental stages including eggs, larvae, pupae and adults, but mostly they are eaten in the immature stages when soft and with reduced exoskeleton (Gahukar, 2011; Charlton et al., 2015). Often, insects are consumed whole, but can also be processed into granular or paste forms or in less recognized forms such as powdered or protein isolates, which could further increase consumer acceptance and reduce the associated stigma and rejection. Extracting proteins, fats, chitin, minerals and vitamins is also possible. Insects are consumed as food in about 80 percent of the world’s nations of which majority are from Africa, Asia and larger parts of South America (van Huis, 2015). Palm weevil and beetle larvae, termites, grasshoppers, crickets and bees form part of the diet of most Asian communities, beetles (Platycoelia lutescens), larvae of the South American palm weevil (Rhynchophorus palmarum) and bearded weevil (Rhinostomus barbirostris) are consumed in parts of South America (Gahukar, 2011; Manditsera et al., 2018). In Southern Africa, the large caterpillar moth (Gonimbrasi abelian) commonly known as the mopane worm is a common protein source. There is an emerging trend towards accepting insects as a source of protein (Gahukar, 2011; Deroy et al., 2015). Crickets are consumed as whole insects in most parts of Africa and Asia but in the west, they are often integrated into food whereby they are dried and ground into a powder. The cricket powder is then incorporated in protein bars, cakes and pasta (Gahukar, 2011; Manditsera et al., 2018). Edible insects are now packaged and sold in the market of Europe and North America as they deliver adequate quantities of healthy protein (DeFoliart, 1999). Agbidye et al. (2009) reported that edible insects could be prepared in the form of snacks, and sold with other meat products like pork and poultry eggs.

Some of the common species of insects that are commonly consumed are beetles, moths, crickets, locusts, caterpillars, palm weevils, termites, and edible grasshoppers (Halloran et al., 2013; Ramos-Elordy, 1998). Some insects could be consumed raw while others need to be cooked in various ways to enhance their organoleptic characteristics. Capinera (2004) reported that the simplest and most primitive way of preparing insects is to roast them in a fire or for example by throwing them in hot ash. Other common methods include boiling or simmering in hot water or soup, roasting them in skewers or frying in hot oil. Insects are commonly cooked together with vegetables and spices (Alexander Kohl, 2016). Traditionally, insects are preserved by drying in the sun, on hot ashes, or oven (Lucas González et al., 2019). Mujuru et al. (2014) posited that boiled insects could be preserved using salt. Also, a study carried out by Klunder et al. (2012) on mealworm larvae (Tenebrio molitor), small cricket (Achetado mesticus) and large crickets (Brachytrupu ssp.) showed that they experienced quality deterioration when stored in the refrigerator (4 ºC) and at room temperature (28–30 ºC). In order to pacify this deteriorating effect, heating or steaming of the insect before storage was recommended. Also, acidifying the insects with vinegar to a pH of 4.5 with drying was considered as the best methods of processing if the insects are to be stored at room temperature without the use of a refrigerator (Klunder et al., 2012). In Africa, consumption of insect is a traditional and cultural way by which low-income earners improve the protein contents of their high carbohydrate diets (Ekpoet al., 2009). Palm beetle larvae (Oryctes rhinoceros) are highly relished food items in Nigeria, especially among the rural populace. Oluwo et al. (2012) reported that the O. rhinoceros larvae could be used as snacks or incorporated into local soups as accompaniments in main meals in Southwest Nigeria.

Rehydration is a complex process aimed at the restoration of previously dried materials in contact with water. The degree of rehydration is dependent on the degree of cellular and structural disruption (Falade and Abbo, 2007). Dehydrated products can be used in many processed or ready-to-eat foods in place of fresh foods and have several advantages such as convenience in transportation, storage, preparation and use (Lewicki et al., 1980). Dehydrated products may be rehydrated before consumption or further processing (Oliveira and Ilincanu, 1999). During rehydration, absorption of water into the tissue results in an increase in the mass. Simultaneously, leaching out of solute (sugars, acids, minerals, vitamins) occurs and both phenomena are influenced by the nature of the product and conditions employed for dehydration (Krokida and Marinos-Kouris, 2003). Currently, literature is sparse on the effect of processing methods on physical, proximate, functional and reconstitution properties of whole and flour larvae. Thus, the objective of this research was to evaluate the effect of pretreatment of palm beetle (Oryctes rhinoceros L.) on the physical, proximate, functional and rehydration properties of whole and flour larvae.

The palm beetle (Oryctes rhinoceros L.) larvae, was harvested from dead raffia palms trees at Yafin village in Badagry local government, Lagos state. The palm beetle larvae was transported in a plastic bucket containing some substrate from the dead raffia palms trees to keep the insects alive and well fed.

3.1.Pre-treatment and processing of the palm beetle larvae

The harvested palm beetle larvae were manually separated from the substrate residue and cleaned by thoroughly rinsing them with clean water for several times. The cleaned palm beetle larvae were degutted, rinsed and steamed at boiling temperature (100 ^oC) for about 10 minutes in a steam colendria, in order to avoid leaching of nutrients into the boiling water, denature the protein, and also to sterilize the larvae before further processing. After the steaming, the larvae were divided into three portions and were subjected to three drying methods: oven drying, sun drying and roasting. Oven drying (202-0AB, Huanghua Mingyu, China) of the steamed larvae was carried out at 55℃ for about 48 hours. The steamed larvae were spread on stainless tray and placed in trays exposed to the sun for about 96 hours, while roasting was done using the roaster (COV- 8320- C, Century electrical products, Ltd, China) at 180℃ for about 20 minutes. After drying or roasting, the dried larvae were allowed to cool for about 30 minutes before milling with hammer mill (8 Lab Mill, Christy and Norris Limited Process Engineers Chelmsford, England). The different flours were sieved using a 800 µm sieve, after which the flour were sealed in airtight polyethylene bag for further analysis.

3.3 Determination of physical characteristics of fresh and processed palm beetle larvae

3.2 Physical Dimensions of fresh and processed palm beetle larvae

The dimensions (weight, length, width, and thickness) of live, roasted, sun-dried and oven dried palm beetle larvae were examined using a Digital Vernier caliper.

3.3.1 Determination of colour parameters of fresh and processed edible larvae

A colourimeter (CR 410 Model, Konica Minolta Sensing Inc., Sakai Osaka, Japan) was used to determine L, a and b values of fresh and processed palm beetle larvae. After calibrating the The chromameter was calibrated with a standard white tile (L = 93.75, a = -5.36, b = 8.50), while the colour values were determined in replicates. The colour parameters of the fresh (unprocessed palm beetle larvae) was taken as the control, hue (H*) angle and colour intensity (∆E) were determined using equations 1 and 2, respectively (Hunt, 1991).

Hue angle = Tan^− 1b/a 1

\(\varDelta E=\sqrt{{(\varDelta \text{L}\text{*})}^{2}+ {(\varDelta a*)}^{2}+{(\varDelta b*)}^{2}}\) 2

3.6 Chemical composition of Palm beetle larvae flour

Using gravimetric method, moisture content of the dried or roasted palm larvae was evaluated using conventional oven drier (Model OV-160, Gallenkamp, UK) until constant weight was attained at 102^oC (AOAC, 2005: method 942.05). Fat and crude protein (method No. 978.04) were respectively evaluated by solvent extraction and standard Kjeldahl distillation (AOAC, 2005). Ash content was determined by incineration up to 600 ^oC. The difference between 100 and the sum of moisture, fat, crude fibre and ash contents was noted as the carbohydrate content.

Mineral analysis

Minerals were analyzed by dry-ashing 1 g of the sample at 550°C in a furnace. The ash obtained was dissolved in 10% HCl, filtered with filter paper and made up to standard volume with dionised water. The dried or roasted palm larvae was processed using acid digestion method, cooled, filtered with distilled water, final volume made to 50 mL and the filtrate was used for the analysis of mineral contents. The mineral contents were determined using the atomic spectrophotometer (Buck Scientific Inc, USA ).

Amino acid profile

Amino acid analysis of the sun-dried, oven-dried and roasted palm beetle larvae was conducted by hydrolysing the samples in sealed ampoules in vacuo with 6 N HCl at 110 for 22 h (Moore, 1963). Excess acid was removed in a flash evaporator under reduced pressure at a temperature of less than 40 C. The sample was then dissolved in buffer and amino acid analysis carried out in a Biochrome30 Amino Acid Analyzer (Peace & Gilani, 2005). The tryptophan in the known sample was hydrolyzed with 4.2 M NaOH (Maria et al., 2004). The known sample was dried to constant weight, defatted, hydrolyzed, evaporated in a rotary evaporator and loaded into Amino Acid Analyzer (Model 120A, Applied Biosystems Inc., Foster City CA, USA).

3.4 Determination of swelling capacity, water and oil absorption capacities, and loose and packed bulk density

The swelling capacity of the processed palm beetle larvae flour was evaluated by a standard (Okaka & Potter, 1977). The ratio of mass of wet sediment to mass of initial dry (flour) sample was determined as the swelling power. Water and oil absorption capacities of the palm beetle larvae flour were evaluated by the method described by Beuchat (1975) and Sosulski et al. (1976), respectively. Water or oil absorption capacity was expressed as gram of water or oil bound per gram of dry powder. Loose and packed bulk densities of the palm beetle larvae flour were evaluated by the method described by Narayana and Narasinga Rao (1984). Packed and loose bulk densities were both calculated as the ratio of the tapped and bulk weight to the volume of the container (g/mL) respectively.

3.4 Determination of Wettability and Dispersibility of palm beetle larvae flour

The wettability of the palm beetle larvae flour was assessed by method described by Falade and Omojola (2008). Palm beetle flour (3 g) was placed around a pestle to block the funnel opening. The pestle was then lifted in order to allow the flour flow through the opening of the funnel into the beaker of distilled water. As soon the all the larvae flour has flown into the beaker of water, a stopwatch was started, and the time taken for a sample of the palm larvae flour to completely get wetted by water was recorded. Dispersibility of the palm beetle larvae flour was determined using the method used by Falade and Bukola (2008). Flour (3 g) was poured over the surface of water in a beaker, and the time taken by the palm larvae flour to distribute itself over the surface of the water, and to sink into the water was noted.

3.5 Determination of Rehydration characteristics of dried and

Prior to the commencement of rehydration of the palm beetle larvae, the oven-dried, sun-dried and roasted whole larvae were further air-dried at 45℃ for about 48 hours in a hot air oven. The palm larvae were rehydrated in 1 L of water at different temperatures of 15 ℃, 30 ℃, and 45℃ respectively, maintaining a sample: water ratio of 1:100. Samples were pre-weighed prior to immersion, and weighed when samples were withdrawn after 0.25, 0.50, 0.75, 1.00, 1.50, 2.00, 2.50, 3.50, 4.50 and 5.500 hours. After the rehydration, moisture content sample of the palm larvae was determined by the method of AOAC (1990). All the experiments were performed in triplicate and average values were reported.

3.7 Statistical analysis

Statistical analyses were carried out using Statgraphics Centurion XVI (Statpoint Technologies Inc., Warrenton/ USA). Data are expressed as mean ± standard deviation (SD) of the performed replications. Data were subjected to one-way analysis of variances (ANOVA), and means were generated and adjusted using LSD post hoc test. Unless otherwise stated, a 95% confidence level (statistical significance at p ≤ 0.05) was considered.

4.3 Physical dimensions of live and processed Palm Beetle Larvae

As expected, the physical dimensions including the weight, length, breadth and thickness of live palm beetle larvae were significantly higher than whole dried, degutted sun-dried, degutted oven-dried and roasted larvae (Table 1). The live larvae showed average weight (18.64 g), length (67.74 mm), breadth (22.56 mm), and thickness (19.115 mm) while the processed larvae varied from 2.85 - 3.86 mm, 36.78 - 38.24 mm, 2010-21.05 mm and 16.50-18.88 mm, respectively. Degutted and 0ven-dried palm beetle showed significantly lower weight compared to the other processed and live larvae. The weight of the roasted and sun-dried larvae were significantly lower than live larvae. The live larvae was significantly longer and wider than the whole oven dried, degutted sun-dried, degutted oven-dried and degutted roasted palm beetle larvae. The degutted sun-dried larvae showed significantly lower thickness than live, whole dried, oven-dried and roasted palm beetle larvae (Table 1). Also, the length and breadth of the live palm beetle were significantly higher than the processed counterparts. Only the sun-dried palm beetle larvae showed significantly lower thickness compared to the other processed and live larvae. The weight and length of live palm beetle larvae reduced with degutting, drying and roasting. This differences in dimensions compared to the live larvae is obviously due to degutting of the palm beetle larvae and moisture loss during dehydration.

4.2 Colour parameters of live and processed Palm beetle larvae

The live palm beetle larvae are significantly higher in lightness (49.93) and yellowness (11.68) than sundried, oven-dried and roasted palm beetle larvae (Table 2). However, sun-dried palm beetle larvae showed darker colour as indicated by the L (28.89), and b (5.60). Visually, the sundried palm beetle larvae showed consistent poorer appearance compared to the lighter colour appearance of the live palm beetle larvae. The roasted palm beetle larvae showed significant better colour parameters and visual appearance than oven- and sun-dried beetle larvae.

4.3 Chemical composition of processed Palm beetle larvae

The proximate and mineral compositions of sun-dried, oven-dried and roasted palm beetle larvae is shown in Table 3. The palm beetle larvae showed relatively high protein content which ranged from 65.46 to 69.99 g/100g. Highest protein value was found in the sun-dried larvae, followed by the oven dried (68.50 g/100g), while the least value was observed in the roasted. According to Tang et al. (2019), the crude protein content of edible insects varies between 40 to 75 g/100g on dry weight basis, Moreover, the protein content of oven dried and lyophilized cricket flour gave high content of protein of 62.68–67.48 % on dry weight basis, respectively (Lucas‑González et al., 2019). Parker et al (2020) reported that the protein content of raw and dried palm weevil larva (Rhynchophoris phoenicis) were 52.72 and 53.04%, respectively. These reported values are higher when compared to conventional meat and chicken. The total ash content of the processed palm larvae samples ranged between 9.75 and 10.27%. Oven dried larvae had the highest ash content, followed by sun dried larvae, while roasted beetle larvae had the lowest ash content. There was no significant difference in the ash content of oven-dried and sun-dried palm larvae. The fat content of the palm beetle larvae ranged from 13.79 - 21.01 g/100g, with the lowest and highest values recorded by sun-dried and roasted larvae, respectively (Table 3). Similarly, Lucas‑González et al (2019) reported that the fat content of oven dried (24.91%) and lyophilized cricket flours (19.32%) varied. Crude fibre content of palm beetle larvae varied insignificantly from 0.55 – 1.23 g/100g. The roasted beetle larvae had lower crude fiber content, while the sun-dried had the highest but there was no significant difference in the crude fiber content of the processed palm beetle larvae. Generally, sun-dried and oven-dried palm beetle showed higher protein, ash, crude fibre and carbohydrate contents, while roasted palm beetle larvae showed higher fat content (Table 3).

Potassium, magnesium and sodium contents of sun-dried, oven-dried and roasted palm beetle larvae varied significantly from 212.6 – 379.1, 58.76 – 184.6, and 104.65 – 170.75 mg/100 g, respectively (Table 3). Moreover, the potassium, magnesium and sodium contents of the processed palm beetle larvae were relatively high. This showed that the processed palm beetle larvae is a rich source of these minerals. The calcium content of the processed palm beetle larvae varied from 9.79 - 11.35 mg/100 g, and was not significantly affected by the drying methods and roasting. Edible insects contains relatively high potassium, magnesium and sodium and iron contents (Tang el., 2019). The iron content of sun-dried-, oven-dried and roasted palm beetle larvae varied significantly from 2.3 - 10.83 mg/100 g, while the zinc content of oven-dried and roasted palm beetle larvae was significantly higher than sun-dried counterpart (Table 3). Also, the copper content of roasted palm beetle larvae was significantly higher than sun-dried and oven-dried counterparts, but the values were generally low. All the values obtain for the amino acid content of the processed palm beetle larvae were within values published in the literature (Tang et al., 2019). According to Tang et al (2019), the trace element content in edible insects varied widely and distinctly. The proximate and trace elements values obtained in this work were comparable to values reported by Parker et al. (2020) for cultivate palm weevil larvae. Lead and cadmium contents of the processed palm beetle larvae were very low (0.00 – 0.8 mg/100 g) and were not significantly affected by drying or roasting (Table 3).

Amino acid profile of processed Palm beetle larvae

The amino acid profile of the sun-dried, oven-dried and roasted palm beetle larvae are shown in Table 4. Generally, the sun-dried palm beetle larvae showed high proportion in most of the amino acids compared to the oven-dried and roasted larvae. High proportion of amino acids in the sun-dried larvae could be due to the lower heat intensity exposure compared to the oven-dried and roasted counterpart. The processed palm beetle larvae contained lower proportions of cysteine and tryptophan and methionine. According to Tang et al (2019), some edible insect contain lower levels of cysteine and tryptophan and methionine. However, the processed beetle larvae are rich in leucine, lysine, phenylalanine, aspartic acid, glutamic acid, isoleucine, leucine, threonine, valine, arginine, histidine and tyrosine. Apart from the deficiency noted, which could be complemented in diets, the processed edible palm beetle larvae would generally meet the amino acids recommendation by the WHO, based on the data provided in the literature (Parker et al., 2020; Tang et al., 2019)

Functional properties of palm beetle larvae flour

Water absorption capacity (WAC) of oven dried beetle larvae flour was significantly higher than the sundried and roasted beetle larvae flours (Table 5). However, the WAC of sundried and roasted palm beetle larvae flour was statistically similar. Also, the WAC of palm beetle larvae was higher than the oil absorption capacity (OAC). The OAC of sun-dried, oven-dried, and roasted were statistically similar, although the flour from the oven-dried beetle larvae showed higher OAC value. The loose bulk density of sundried larvae flour was significantly higher than oven-dried and roasted flours. However, the packed bulk density of oven-dried and roasted palm beetle flour were significantly higher than the sundried flour. Bulk density indicates the porosity of a food product which impact the design of the package and can be used in determining the type of the required packaging.

Lower wettability and dispersibility (in sec) are indicative of better reconstitution properties. The lower wettability and dispersibility values showed by sun-dried palm beetle larvae flour indicated better ease of reconstitution properties (Table 5). Generally, oven-dried palm beetle larvae flour indicated significantly poorer wettability and dispersibility values. However, sundried beetle larvae flour gave significantly better wettability and dispersibility values.

Rehydration Characteristics

The increase in weight of the sun-dried, oven-dried and roasting palm beetle larvae during rehydration was obviously due to uptake of water. Expectedly, moisture content of sundried, oven-dried and roasted palm beetle larvae increased during rehydration. The sun-dried larvae showed steeper curves compared to oven-dried and roasted larvae, indicating higher moisture contents and relatively higher rehydration. However, the roasted larvae consistently showed lower moisture contents, which was indicative of lower rehydration capacity. Lower moisture contents, and by extention rehydration property, of the roasted and oven-dried larvae could be attributed to the heat treatment and damage experienced during oven drying and roasting. The milder heat treatment experienced by the sun-dried larvae may have contributed to its ability to imbibe more moisture.

The immersion water temperature influenced the rehydration of palm beetle larvae. Consistently, sun-dried, oven-dried and roasted palm beetle larvae rehydrated at higher water temperature showed higher moisture contents. Sun-dried palm beetle larvae which was rehydrated at 45 ^oC showed consistently higher moisture content throughout the rehydration period compared to the those immersed at 15 ^oC and 30 ^oC. Expectedly, sun-dried, oven-dried and roasted palm beetle larvae rehydrated at 15 ^oC showed lower moisture contents, indicative of lower rehydration capacity. The higher moisture contents showed at higher rehydration temperature could be due to faster moisture diffusion.

This research work examined the physical, chemical, and rehydration characteristics of palm larvae insects. Weight and length of processed palm beetle larvae reduced with degutting, drying and roasting. Physical, chemical and rehydration characteristic of the palm larvae varied widely with drying method and roasting. Palm beetle larvae showed high crude protein and fat contents, while the amino acids profile of the processed larvae showed full complement of amino acids, with the sun-dried larvae showing higher proportions than oven-dried and roasted larvae. Rehydration of processed palm beetle larvae was influenced by drying method or roasting, and immersion water temperature (15–45 ^oC). Palm beetle larvae contains rich sources of nutrient which could be used in food supplementation to combat protein malnutrition.

Conflict of Interest:

Authors declare that there is no conflict of interest

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Table 1. Physical dimensions of Palm beetle larvae (Oryctes rhinoceros)

Samples	Weight (g)	Length (mm)	Breadth (mm)	Thickness (mm)
Live Larvae	18.64±3.01^c	67.74±8.33^b	22.56±2.04^b	19.16±1.98^b
Dried whole larvae	3.86±0.66^b	38.24±3.71^a	20.40±1.29^a	18.88±1.8^b
Sundried degutted larvae	3.12±1.21^ab	37.89±2.85^a	20.55±2.69^a	16.50±2.81^a
Oven-Dried degutted larvae	2.85±0.37^a	38.20±3.73^a	20.10±1.0^a	18.39±1.68^b
Roasted Larvae	3.45±1.45^ab	36.78±3.39^a	21.05±3.27^a	18.18±3.3^b

Mean values ± Standard deviation (n=20). Mean values for samples in the same column with different superscripts are significantly different at 5% probability level (p˂ 0.05).

Table 2. Colour parameters of live, sundried, oven-dried and roasted palm beetle larvae (Oryctes rhinoceros)

Colour parameter	Live Larvae	Sun-dried	Oven-dried	Roasted
L	49.93±0.10^a	28.89±0.59^d	44.44±0.12^c	46.32±0.37^b
a	-0.86±0.01^b	1.38±0.16^a	-1.08±0.02^c	-1.18±0.02^c
b	11.68±0.16^a	5.60±0.19^b	5.15±0.02^c	5.45±0.03^b
ΔE	32.66±0.15^a	9.14±0.39^d	25.76±0.12^c	27.25±0.21^b
Hue angle	81.03±1.23^b	58.38±6.46^c	107.04±1.66^a	112.53±1.18^a

Mean values ± Standard deviation (n=3). Mean values for samples in the same row with different superscripts are significantly different at 5% probability level (p˂ 0.05).

Table 3. Proximate composition (g/100g) and minerals (mg/100g) of sun-dried, oven-dried and roasted Palm beetle larvae (Oryctes rhinoceros)

	Sun-dried	Oven-dried	Roasted
Protein	69.99±0.56 ͣ	68.50±0.41ᵇ	65.46±0.06 ͨ
Ash	10.01±0.98 ͣ	10.27±0.095 ͣ	9.75±0.37 ͣ
Fat	13.79±0.89 ͨ	16.00±0.6ᵇ	21.01±0.46 ͣ
Crude fibre	1.23±0.02ᵇ	1.14±0.065 ͣ	0.55±0.01 ͨ
Carbohydrate	4.88±0.50 ͣ	4.10±0.96 ͣᵇ	3.22±0.75ᵇ
Calcium	9.79±0.25 ͣ	15.86±2.62 ͣ	11.35±0.17 ͣ
Magnesium	58.76±14.09 ͣ	108±2.83ᵇ	184.6±4.24 ͨ
Potassium	212.6±1.56 ͣ	379.1±5.8 ͨ	337±1.41ᵇ
Sodium	104.65±1.2 ͣ	152.3±3.39ᵇ	170.75±0.35 ͨ
Iron	2.3±0 ͣ	6.58±0.04ᵇ	10.83±0.28 ͨ
Zinc	2.6±0.14 ͣ	6.35±0.07ᵇ	6.7±0ᵇ
Copper	0.23±0.04 ͣ	0.25±0 ͣ	0.45±0.07ᵇ
Lead	0.8±0.35 ͣ	0.33±0.25 ͣ	0±0 ͣ
Cadmium	0.03±0.04 ͣ	0±0 ͣ	0±0 ͣ

Mean values ± Standard deviation (n=3). Mean values for samples in the same column with different superscripts are significantly different at 5% probability level (p˂ 0.05).

Table 4. Amino acid (g/100g) profile of sun-dried, oven-dried and roasted Palm beetle larvae (Oryctes rhinoceros)

Amino acid	Sun-dried	Oven-dried	Roasted
Leucine	7.42±0.69^a	6.46±0.06^a	6.98±0.06^a
Lysine	4.70±0.13^a	4.34±0.04^b	4.75±0.06^a
Isoleucine	3.93±0.13^a	3.53±0.04^b	4.08±0.08^a
Phenylalanine	5.46±0.21^a	4.56±0.07^b	5.28±0.04^a
Trytophan	0.74±0.04^a	0.64±0.06^a	0.75±0.01^a
Valine	5.35±0.1^a	4.70±0.00^b	5.32±0.06^a
Methionine	2.68±0.35^a	2.28±0.01^a	2.48±0.06^a
Proline	4.98±0.02^b	4.41±0.07^a	5.08±0.16^b
Arginine	6.46±0.39^a	5.71±0.06^b	6.15±0.04^ab
Tyrosine	3.53±0.13^a	3.18±0.12^b	3.44±0.01^ab
Histidine	3.47±0.08^a	3.11±0.02^b	3.36±0.08^a
Cystine	1.76±0.01^a	1.42±0.04^b	1.79±0.05^a
Alanine	5.14±0.31^a	5.00±0.00^a	4.88±0.06^a
Glutamic acid	10.87±0.3^a	9.75±0.11^b	10.6±0.07^a
Glycine	4.69±0.27^a	3.94±0.04^b	4.44±0.08^ab
Threonine	3.71±0.19^a	3.52±0.16^a	3.6±0.04^a
Serine	4.55±0.49^a	3.72±0.04^a	4.26±0.08^a
Aspartic acid	7.49±0.35^a	6.67±0.11^b	7.28±0.05^ab

Mean values ± Standard deviation (n=3). Mean values for samples in the same column with different superscripts are significantly different at 5% probability level (p˂ 0.05).

Table 5. Functional properties of Palm beetle larvae (Oryctes rhinoceros) flour

	Water Absorption capacity	Oil absorption capacity	Loose Bulk Density	Packed Bulk Density	Wettability (sec)	Dispersibility (sec)
Sun-dried	1.80±0.10^b	1.20±0.10^a	0.41±0.00^a	0.56±0.01^b	15.15±0.18^c	18.77±1.08^b
Oven-dried	2.03±0.15^a	1.33±0.15^a	0.39±0.01^b	0.60±0.01^a	24.67±1.53^a	26.00±1.73^a
Roasted	1.77±0.06^b	1.23±0.15^a	0.38±0.01^b	0.60±0.02^a	19.92±0.43^b	24.13±1.21^a

Mean values ± Standard deviation (n=3). Mean values for samples in the same column with different superscripts are significantly different at 5% probability level (p˂ 0.05).

Physical, nutritional, functional and rehydration properties of palm beetle (Oryctes rhynoceros) larvae as affected by drying and roasting

Status:

Version 1

Abstract

Figures

Introduction

Materials and Methods

3.3 Determination of physical characteristics of fresh and processed palm beetle larvae

3.6 Chemical composition of Palm beetle larvae flour

Mineral analysis

Result and Discussion

Conclusion

Declarations

Conflict of Interest:

References

Tables

Status:

Version 1