An optimal designed experiment for the alkaline hydrolysis of feather keratin

Małgorzata Dąbrowska,Agata Sommer,Hanna Staroszczyk,Antoni Taraszkiewicz,Izabela Sinkiewicz

doi:10.1007/s11356-021-17649-2

Małgorzata Dąbrowska, Agata Sommer + Show 3 more

Open Access

https://doi.org/10.1007/s11356-021-17649-2

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Abstract

Feathers, burdensome waste from the poultry industry, can be a cheap source of keratin, a protein with excellent physicochemical, biological, and mechanical properties. Acid and alkaline hydrolyses are usually adopted for isolation of keratin from its natural resources. This study aimed at assessing the statistically significant effect of input variables in the alkaline hydrolysis of keratin from chicken feathers on the process yield and on the molecular weight of peptides obtained. The effect of the volume ratio of 1M NaOH to the feathers’ mass, the hydrolysis time, and the shaking speed of the reaction mixture on the process yield were analyzed. The use of statistical analysis at the design step of experiment allowed reducing the trial number from 27 to 9. Among the input variables analyzed, only the volume ratio of 1M NaOH to the feathers’ mass had a significant effect on the process yield, while none of them significantly affected the molecular weight of the peptides obtained. All hydrolysates were dominated by two peptides’ fractions, with molecular weights of ca. 130 and 250 kDa, and mixture of many peptides of weight close to 10 kDa and smaller. Alkaline hydrolysis of feather keratin yielded protein hydrolysates soluble over a wide pH range.

Highlights

Over the past 20 years, global plastic production has increased by around 260 million tons, reaching 359 million tons annually (PlasticsEurope 2020)
Undissolved feather residues were found in all trials, except for sample no. 9, in which the highest input variable parameters were used, i.e., volume of 1M NaOH, 225 mL, the hydrolysis time, 32 h, and shaking speed of the reaction mixture, 200 rpm
The randomized Latin square statistical program allowed to assess the significance of the influence of three input variables, with three levels of variability, on the final result of alkaline hydrolysis of soluble keratin from chicken feathers, limiting the number of trials from 27 to 9 necessary to perform, which reduced research cost and time

Summary

Introduction

Over the past 20 years, global plastic production has increased by around 260 million tons, reaching 359 million tons annually (PlasticsEurope 2020). Disposal of these materials is an increasing environmental challenge. Many toxic compounds migrate into the soil and groundwater, contaminating them and eventually killing the ecosystems that live there (Vethaak and Leslie 2016; Haider et al 2019). When plastics are used for food packaging, the harmful compounds can be released into food, and into consumer organisms, where they can bioaccumulate (Vethaak and Leslie 2016).

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