Single cell Protein production by utilizing different fruits & vegetables wastes


Loveleen Kaur Sarao1 and Shruti Puri 2

Food wastes are the parts of fruits, vegetables or any other food stuff which are unconsumed and unused. They have unfavourable morphological characteristics owing to lack of proper handling operations, or simply discarded for diverse reasons (Sagar et. al., 2018). Starting from production stage to consumer domain, about 1.3 billion tons per year food is wasted or lost. Out of all the food waste commodities, fruits and vegetables account for 44%.

When a raw material enters food processing line, both product and wastes are produced. About 25-30% of fruit waste is in form of peels, pomace and seeds (Salim et. al., 2017). Dicing of papaya produces 8.5% of peels and 6.5% of seeds as waste product whereas mango processing produces 11% of peels, 13.5% of seeds and 18% of inoperable pulp (Sagar et. al., 2018). A lot of study has  been done  on utilization of these wastes to produce value added products. Peels can be used for production of methane, hydrogen and ethanol. They have high nutritive content and thus can be used as single cell protein by carrying out fermentation process (Kodagoda et. al., 2017).

Proteins are building blocks of all the living beings. Proteins are important for life processes, for proper growth and development in living beings. Its deficiency leads to a number of disorders because essential amino acids which cannot be synthesized by the body itself are not replenished. The most common deficiency is known as kwashiorkor (Hermann, 1990). Single Cell Protein (SCP) is one of the easiest, cheap and innovative ways to solve the protein deficiency problem. In the late 1960s, the production of Single Cell Protein began.

Single Cell Protein refers to dead, dry cells of micro-organisms such as yeast (Candida, Saccharomyces, etc.), bacteria (Cellulomonas, Alcaligens, etc.), algae (Spirulina, Chlorella, etc.) and  molds (Trichoderma, Fusarium, Rhizopus, etc.). The term SCP is appropriate as most of the microorganisms grow as single or filamentous individuals. SCP is rich in protein content (about 60-82% of dry cell weight), fats, carbohydrates, nucleic acids, vitamins and minerals. SCP is rich in most of the essential amino acids such as lysine, methionine. SCP can be used instead of the expensive protein source like soybean and fish (Gour et. al., 2015).

Different micro-organisms such as bacteria, fungi, yeast and algae are used in the production of Single Cell Protein. Out of all, yeast is considered to be the best microbes for the production of SCP as it is easy to harvest because of their large cell size, lower nucleic acid content, high lysine content and ability to grow on the acidic conditions. Disadvantages of using bacterial cell are that it has small cell size and high nucleic acid content. To decrease the level of nucleic acid, certain processing step has to be added which increases the production rate. Disadvantages of using fungal cell are that it has low growth rate and lower protein content. Algae has cellulosic cell walls which cannot be digested by the human digestive system.

In the production of fruits and vegetables, India is considered to be second largest producer. Approximately 40% of total mass is the waste that includes its peels, pulp and seeds that are generated from fruits. According to researchers, the fruit wastes have high nutritional value e.g. banana peels have more protein content than banana pulp itself (Pereira et. al., 2013). Thus, fruit wastes are suitable as it is cheap substrate for the production of SCP. This will also help in solving the waste disposal problem to some extent and control pollution and will also reduce the protein shortage.  The utilization of the fruit waste can be done to produce value added products, production of low cost protein and to meet the protein demand of growing population.

1 Punjab Agricultural University , Ludhiana.
2 Department of Food Science, MCM DAV College for Women,Chandigarh.

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