Semester

Spring

Date of Graduation

2023

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Animal and Nutritional Sciences

Committee Chair

Kristen Matak

Committee Co-Chair

Jacek Jaczynski

Committee Member

Jacek Jaczynski

Committee Member

Yong-Lak Park

Abstract

The weight changes, survival/mortality rates, and proximate compositions of Tenebrio molitor (yellow mealworm) larvae whose diets were supplemented with apple pomace were analyzed after a 4-week feeding study to examine the nutritional quality of the insects for use as a future potential food source. Going forward, the terms “mealworm(s)”, "yellow mealworm(s)”, “T. molitor” will be used interchangeably and will always refer to the same species. The mealworm larvae were randomly divided into two groups: in addition to standard worm chow, one group was given 15 g/week of non-nutritive water-storing polymer crystals and the other was given apple pomace ad libitum which was made in-house. Weight changes were not significantly different between the two groups after four weeks (p > 0.05). Survival rates were similar; however, there was a correlation between increased rates of pupation and decreased survivability rates among the survivors (ρ < 0.05) in both groups. There were no significant differences in protein, fat, and ash between the two groups (p > 0.05; dry weight basis). The crude protein in water bead (WB) worms was 38.38 ± 0.05g/100 g compared to apple pomace worms (AP) which contained 38.33 ± 0.07 g/100 g. The total fat in the WB worms was 51.94 ± 0.15 g/100 g, compared to 52.27 ± 0.09 g/100 g in the AP worms. The ash content was also similar between WB worms (0.20 ± 0.001) and AP worms (0.16 ± 0.002). On the other hand, the moisture content of the WB mealworms was greater than (66.89± 0.01g/100 g) the AP mealworms (63.89 ± 0.01; p< 0.05). Results of this study show that mealworms are a significant source of protein, and when mealworm feed is supplemented with apple pomace, protein concentration is not affected.

The solubility, proximate composition, amino acid profile, SDS-PAGE summary, thermal abilities, mineral composition, and color of Tenebrio molitor (yellow mealworm) larvae were studied to determine the nutritional quality and functional properties of the insects. The mealworm larvae were tested in various forms (fresh, frozen whole mealworms; freeze-dried whole mealworms; fresh, frozen mealworm protein isolate; and freeze-dried mealworm protein isolate) to determine if there were any differences in the qualities of the mealworms when proteins were isolated via isoelectric solubilization/precipitation (ISP) or freeze-dried before various analyses. The greatest protein solubility was seen at a pH of 12. On a dry weight basis, the protein concentration of the fresh, frozen whole mealworms (75.30±0.02 g/100g) was greater than the freeze-dried mealworms (66.33±0.02 g/100g); (p0.05). T. molitor contains all essential amino acids; however, tryptophan is limiting. Whole freeze-dried mealworm samples had significantly greater concentrations of amino acids when compared to mealworm protein isolate samples. SDS-PAGE revealed that actomyosin was seen across the Mini-PROTEAN TGX precast Gel; it was effectively isolated and did not degrade when ISP was completed. Differential scanning calorimetry showed that mealworm protein isolates had more drastic transitions than freeze-dried whole mealworms. Mealworms are not a good source of calcium, but they do provide potassium, phosphorus, and especially magnesium. The fresh, frozen whole mealworms contained a significantly greater amount of these minerals than freeze-dried mealworm protein isolate samples (pTenebrio molitor can provide a reliable protein option while possibly mitigating environmental impacts; therefore, it is imperative to further investigate the potential of insect proteins.

Comments

My signed shuttle sheet where my committee signed off on my thesis was already submitted to Dr. Kimberly Barnes (dean) - I do not currently have a copy of it, but Dr. Barnes does.

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