**7. Technologies for renewable energy generation from food/agricultural waste**

Currently in many countries food waste are incinerated together with other combustible municipal wastes or landfilled for possible recovery of energy. However, due to these two approaches environment and economy of the countries are more stressed. Due to its composition of organic and nutrient-rich content, theoretically FW can be utilized as a useful resource for biofuel production through various processes of fermentation. It has attracted increasing interest in the production of biogas, hydrogen, ethanol and biodiesel as final products. Therefore, this section reviews all the food waste fermentation technologies for renewable energy generation.

#### **7.1 Production of ethanol**

The rapid global demand for the for the ethanol which has wide application in industries is increasing day by day. The main purpose of ethanol is to produce ethylene which is the main raw materials for the production of polyethylene and other plastics that is the reason for the high demand i.e. more than 140 million tonnes per year. Even the bioethanol has gained interest that is produced from cheap feedstocks [42, 43]. The source of bioethanol is the waste from starch and cellulose rich crops, e.g. sugar cane, rice and potato [44]. With the help fermentation in presence of *Saccharomyces cerevisiae* starch undergo breakdown resulted in the conversion of glucose by commercial enzymes and finally production of ethanol. In case of cellulose the breakdown due to hydrolysis is more difficult. If the FW contain large number of cellulose feedstocks than hydrolysis will become difficult, that is why, for the production of ethanol use of abundant and cheap wastes such as municipal, lignocellulosic and food waste has been explored as alternative substrates [45, 46].

#### **7.2 Production of hydrogen**

Hydrogen in the form of compressed gas gives high energy yield (142.35 kJ/g) which can also be produced from FW. The production of hydrogen is associate with the food waste containing higher amount of carbohydrate. The production rate of 0.9 to 8.35 mol H2/mol hexose is generated from thee food waste according to recent studies [47]. The production of H2 is influenced by many factors such as process configurations, pre-treatments and the composition of FW.

#### **7.3 Production of methane**

Methane is used as a fuel for ovens, homes, water heaters, automobiles, turbines, and other things. Because of its low cost, the production of methane via anaerobic processes is a good approach for management of waste, low production of residual waste and its utilization as a renewable energy source [48, 49]. In addition to biogas, a nutrient-rich digestate produced can also be used as soil conditioner or fertilizer. [50] investigated two-stage anaerobic digestion of fruit and vegetable wastes, in which 95.1% volatile solids (VS) conversion with a methane yield of 530 mL/g VS was achieved. [51] FW was converted to methane using a 5-L continuous digester fed with an organic loading rate (OLR) of 7.9 kg VS/m3 , resulting 70% VS conversion with a methane yield of 440 mL/g VS. [52] the methane production capacities of about 54 different fruit and vegetable wastes ranged from 180 to 732 mL/g VS depending on the origin of wastes.

#### **7.4 Production of biodiesel**

Biodiesel is synthesized through direct transesterification/acid catalyst using alkaline FW converted to fatty acids and biodiesel via various oleaginous microorganisms [53–56]. Many yeast strains produce microbial oil and then it can be used as the substitute of plant oils due to their similar fatty acid compositions. It also can be used as raw material for the production of biodiesel [57]. It has been found that the potential of FW hydrolyzate as culture medium and nutrient source in microalgae cultivation contributes for production of biodiesel [58].

In terms of prevention and concern towards economic and environment, management of FWs is utmost urgent and important to be implemented. The bioconversion of FW is economically viable for the conversion of biodiesel, ethanol, hydrogen, and methane. However, problems associated with FW in terms of transportation/collection should also be monitored. Nevertheless, the low or no cost of food waste along with the environmental benefits considering the waste disposal would balance the initial high capital costs of the biorefineries.

#### **7.5 Production of bioactive compounds by fermentation of food waste**

Bioactive and compounds are the two words which gives the term "Bioactive compounds". Scientifically, the meaning of this term is several molecules that have some biological activity.

These compounds are naturally present lesser content in plants and food stuffs, they are phytochemicals [59] and potentially able to growth in metabolism for the betterment of human health. Bioactive compounds are extremely heterogeneous class of compounds includes plant growth factors, alkaloids, mycotoxins, foodgrade pigments, antibiotics, flavonoids and phenolic acids etc. with dissimilar chemical structures (hydrophilic or lipophilic), specific to ubiquitous distribution

**23**

pollution.

**9. Conclusion**

*Food Waste and Agro By-Products: A Step towards Food Sustainability*

oxidative species and possess the potential biological action [60, 61].

transformation into value added products through microorganisms [34].

Agricultural industries generate a huge amount of wastes and by-products during production, handling and processing of agricultural products. Disposal of these wastes has a serious financial and ecological concern due to its detrimental environmental effects [62]. Therefore, to discover alternative methods of recycling and reprocessing of these wastes is a significant target taken into consideration globally. These wastes and by-products represent huge potential which have not been fully exploited, causing a loss of economic opportunity. There is thus need to identify the reasons for underutilization of agricultural by-products so that they can be addressed through suitable strategies and policy interventions. Part of the reason for the underutilization of agricultural by-products is due to lack of awareness about their properties and potential economic benefits. Proper research and studies need to be carried out on assimilating different value-added product manufacturing process. Value addition of by-products generates economic value as it facilitates the process of economic diversification by opening up new agricultural market and providing alternatives to low-cost commodity production, by offering new perspectives for the management of resources and by providing economic opportunities and environmental benefits. Markets for agricultural by-products are essential for their commercialization, value addition and efficient utilization. The lack of markets for the by-products restricts the use of crop residue to produce biofuels. So, there is a need to establish markets and to keep operational expenses of its value addition low enough to encourage the production and utilization of value-added products. These by-products also represent potential solutions to the problems of animal nutrition. Technologies needs to be developed for better utilization considering factors, such as characteristics of individual wastes and the environment in which they are produced, reprocessed and utilizied, such technologies need to convey products that are safe not only for animal feed use, but also from the point of view of human feeding. The proper utilization of agricultural wastes and by-products has the potential to support entire industries, increase income and valuable employment opportunities, develop rural areas and solve the problem of waste and environmental

The world Population is increasing rapidly with the decreasing trend of natural resources are at the same time. Raising concerns over the security of global food

in nature, significant amount present in foods and in human body, efficient against

Through various food industries a large number of by-products or wastes are produced worldwide due to which it leads to environmental degradation. So, nowadays many approaches and new techniques are introduced for the use of the wastes, because these by-products are an excellent source of various bioactive components and beneficiary for human health. The composition of these wastes mainly depends on the waste source/type. Approximately half of the waste produced from food processing factories is lignocellulosic in nature. The dissimilar types of waste produced by food industries can be fortified by various processes. One of the oldest approaches is fermentation and carried out in three types of processes, that are carried out such as solid state, submerged and liquid fermentation used for product

*DOI: http://dx.doi.org/10.5772/intechopen.96177*

**8. Future perspectives**

#### *Food Waste and Agro By-Products: A Step towards Food Sustainability DOI: http://dx.doi.org/10.5772/intechopen.96177*

in nature, significant amount present in foods and in human body, efficient against oxidative species and possess the potential biological action [60, 61].

Through various food industries a large number of by-products or wastes are produced worldwide due to which it leads to environmental degradation. So, nowadays many approaches and new techniques are introduced for the use of the wastes, because these by-products are an excellent source of various bioactive components and beneficiary for human health. The composition of these wastes mainly depends on the waste source/type. Approximately half of the waste produced from food processing factories is lignocellulosic in nature. The dissimilar types of waste produced by food industries can be fortified by various processes. One of the oldest approaches is fermentation and carried out in three types of processes, that are carried out such as solid state, submerged and liquid fermentation used for product transformation into value added products through microorganisms [34].

## **8. Future perspectives**

*Innovation in the Food Sector Through the Valorization of Food and Agro-Food By-Products*

configurations, pre-treatments and the composition of FW.

cultivation contributes for production of biodiesel [58].

would balance the initial high capital costs of the biorefineries.

**7.5 Production of bioactive compounds by fermentation of food waste**

Bioactive and compounds are the two words which gives the term "Bioactive compounds". Scientifically, the meaning of this term is several molecules that have

These compounds are naturally present lesser content in plants and food stuffs, they are phytochemicals [59] and potentially able to growth in metabolism for the betterment of human health. Bioactive compounds are extremely heterogeneous class of compounds includes plant growth factors, alkaloids, mycotoxins, foodgrade pigments, antibiotics, flavonoids and phenolic acids etc. with dissimilar chemical structures (hydrophilic or lipophilic), specific to ubiquitous distribution

Hydrogen in the form of compressed gas gives high energy yield (142.35 kJ/g) which can also be produced from FW. The production of hydrogen is associate with the food waste containing higher amount of carbohydrate. The production rate of 0.9 to 8.35 mol H2/mol hexose is generated from thee food waste according to recent studies [47]. The production of H2 is influenced by many factors such as process

Methane is used as a fuel for ovens, homes, water heaters, automobiles, turbines, and other things. Because of its low cost, the production of methane

low production of residual waste and its utilization as a renewable energy source [48, 49]. In addition to biogas, a nutrient-rich digestate produced can also be used as soil conditioner or fertilizer. [50] investigated two-stage anaerobic digestion of fruit and vegetable wastes, in which 95.1% volatile solids (VS) conversion with a methane yield of 530 mL/g VS was achieved. [51] FW was converted to methane using a 5-L continuous digester fed with an organic loading rate (OLR)

, resulting 70% VS conversion with a methane yield of 440 mL/g

via anaerobic processes is a good approach for management of waste,

VS. [52] the methane production capacities of about 54 different fruit and vegetable wastes ranged from 180 to 732 mL/g VS depending on the origin

Biodiesel is synthesized through direct transesterification/acid catalyst using alkaline FW converted to fatty acids and biodiesel via various oleaginous microorganisms [53–56]. Many yeast strains produce microbial oil and then it can be used as the substitute of plant oils due to their similar fatty acid compositions. It also can be used as raw material for the production of biodiesel [57]. It has been found that the potential of FW hydrolyzate as culture medium and nutrient source in microalgae

In terms of prevention and concern towards economic and environment, management of FWs is utmost urgent and important to be implemented. The bioconversion of FW is economically viable for the conversion of biodiesel, ethanol, hydrogen, and methane. However, problems associated with FW in terms of transportation/collection should also be monitored. Nevertheless, the low or no cost of food waste along with the environmental benefits considering the waste disposal

**7.2 Production of hydrogen**

**7.3 Production of methane**

of 7.9 kg VS/m3

**7.4 Production of biodiesel**

some biological activity.

of wastes.

**22**

Agricultural industries generate a huge amount of wastes and by-products during production, handling and processing of agricultural products. Disposal of these wastes has a serious financial and ecological concern due to its detrimental environmental effects [62]. Therefore, to discover alternative methods of recycling and reprocessing of these wastes is a significant target taken into consideration globally. These wastes and by-products represent huge potential which have not been fully exploited, causing a loss of economic opportunity. There is thus need to identify the reasons for underutilization of agricultural by-products so that they can be addressed through suitable strategies and policy interventions. Part of the reason for the underutilization of agricultural by-products is due to lack of awareness about their properties and potential economic benefits. Proper research and studies need to be carried out on assimilating different value-added product manufacturing process. Value addition of by-products generates economic value as it facilitates the process of economic diversification by opening up new agricultural market and providing alternatives to low-cost commodity production, by offering new perspectives for the management of resources and by providing economic opportunities and environmental benefits. Markets for agricultural by-products are essential for their commercialization, value addition and efficient utilization. The lack of markets for the by-products restricts the use of crop residue to produce biofuels. So, there is a need to establish markets and to keep operational expenses of its value addition low enough to encourage the production and utilization of value-added products. These by-products also represent potential solutions to the problems of animal nutrition. Technologies needs to be developed for better utilization considering factors, such as characteristics of individual wastes and the environment in which they are produced, reprocessed and utilizied, such technologies need to convey products that are safe not only for animal feed use, but also from the point of view of human feeding.

The proper utilization of agricultural wastes and by-products has the potential to support entire industries, increase income and valuable employment opportunities, develop rural areas and solve the problem of waste and environmental pollution.

#### **9. Conclusion**

The world Population is increasing rapidly with the decreasing trend of natural resources are at the same time. Raising concerns over the security of global food

due to the disparity between food wastage and food poverty, highlights the moral and social food waste dimensions. This chapter suggests that the first step towards a more sustainable resolution of the growing food waste issue is to adopt a sustainable production and consumption approach and tackle food surplus. The distinction between food surplus and food waste on one hand, and avoidable and unavoidable food waste on the other, are crucial in the process of identifying the most appropriate options for addressing the food waste challenge. This study proposes the food waste hierarchy as a framework to identify and prioritize the options for the minimization and management of food surplus and waste throughout the food supply chain. The proposed food waste hierarchy aims to challenge the current waste management approach to food waste, contribute to the debate about waste management and food security, and influence the current academic thinking and policies on waste and food to support more sustainable and holistic solutions.

Preventing food waste in agriculture and food processing requires improved infrastructure and technological solutions in harvesting, storage, transport and distribution, supported by large-scale investment and local policies. Waste management policies should be integrated and aligned with the wider policies on food, agriculture, food standards, food poverty alleviation and sustainable production and consumption.
