Whey, renewable material

The top left quarter of Figure 10.4 comprises thermosetting bio-derived resins that typically do not feature in packaging applications and so will not be discussed further. Most interestingly, in the context of biodegradable, renewable materials is the top right quarter that comprises polylactic acid (PLA), starch, polyhydroxy butyrate, whey protein, and so on. Each of the petrochemical and non-petrochemical derived IWSPs are discussed in turn below. 

There has been recent interest in lactic acid polymers and copolymers. These materials are environmentally attractive in that renewal and cheap source materials such as potato waste and cheese whey may be used. Such materials have been used for some time in degradable and resorbable surgical sutures but recent efforts have been directed at food packaging applications. There is... 

There have been many attempts to produce LA from cheap raw materials such as starchy and cellulosic materials, whey, and molasses. Among these, starchy and ligno-cellulosic materials are currently receiving a great deal of attention, because they are cheap, abundant, and renewable (Wee et al., 2006). One bottleneck for LA production from starchy and lignocellulosic materials is the cost of pretreatment of raw materials. 

If a fermentation process is used for PHA synthesis this problem can partially be overcome by using cheap surplus and waste materials as renewable carbon sources (e.g. molasses, whey, cellulose hydrolysate) or other cheap carbon sources from fossil resources like methanol derived from natural gas, because roughly 50% of the total production costs derive from the carbon source costs. Unfortunately many of the well known production strains can not be used for PHA production from such substrates, because these microbial strains show either low yields or low production rates, when they grow on these substrates, or they simply cannot utilize these carbon sources at all. These drawbacks can be overcome either by isolating new microbial strains or by applying genetically modified strains for the production process. 

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