Page 402 - Refining Biomass Residues for Sustainable Energy and Bioproducts

Agroindustry wastes: biofuels and biomaterials feedstocks for sustainable rural development 365

Table 16.3 Fruit and vegetable processing wastes.
Fruits/Vegetables Nature of waste Approx. waste (%)

Citrus Peel, rag, seed 50
Banana Peel 35
Pineapple Skin, core 33
Mango Peel, stones 45
Apple Peel, pomace, seed 25
Grape Stem, seed, skin 20
Tomato Skin, core, seed 20
Guava Peel, core, seed 10
Pea Shell 40
Potato Peel 15
Onion Outer leaves 10

Data from Ajila, C.M., Brar, S.K., Verma, M., Prasada Rao, U.J.S., 2011. Sustainable solutions for agro processing
waste management: an overview. In: Malik, A.G.E. (Ed.), Environmental Protection Strategies for Sustainable
Development. Springer, Dordrecht.
literature survey says that biodiesel can be prepared from soap stock obtained from
oil refinery (Modiba et al., 2015). The pressed solid after expelling of oil comes out
as oil press cake. The cake is rich in proteins, fibers, antioxidants, vitamins, and
minerals. It has been used as animal feed and also as food supplements after
suitable treatments for better palatability (Sunil et al., 2015). Rapeseed oil cake can
be utilized for biooil and biochar production using cold extraction pressing techni-
ques (Ozcimen and Karaosmanoglu, 2004). The protein content of cake may be as
high as 34% in the case of sesame cake. An extensive review on the oil cakes com-
position and their use as food supplement are presented by Ramachandran et al.
(2007). The functional and nutritional properties have been successfully modified
by solid-state fermentation (SSF) process in recent past (Sadh et al., 2018a,b). Oil
cake is a good substrate for microbial growth for production of some flavor com-
pounds by SSF.
India ranks first in milk production, and huge volume of effluents is generated
from milk-processing industries. Approximately 0.2 10 L of effluent is generated
from processing of 1 L of milk. The whey that comes out of cheese processing
industries has composition of 4.5% 5% lactose, 0.6% 0.8% protein, 0.4% 0.5%
lipids (Panesar et al., 2016). The biochemical oxygen demand (BOD) of dairy efflu-
ent increases due to the presence of lactose in large quantity, and higher BOD
wastewater causes environmental problems. If the components such as lactose and
protein are removed from effluents, not only it will reduce the risk of environmental
pollution by reducing the BOD, but also the harvested lactose and proteins can be
used for diversified food uses. Different cost-effective and efficient techniques have
been developed and used for lactose and protein recovery from dairy effluents in
recent past (Das et al., 2016). Dairy wastewater can be used for the production of
biogas rich in carbon dioxide content, which can eventually be used for methane
production (Jurgensen et al., 2018).