Changes

[[Cell aggregation]] occurs throughout [[microbiology]], in [[bacteria]], [[filamentous algae]], [[fungi]] and [[yeast]] (Lewin, 1984; Stratford, 1992). Yeast are capable of forming three aggregates; mating aggregates, for DNA exchange; chain formation, for development and differentiation; and flocs as a survival strategy in adverse conditions (Calleja, 1987). Brewing strains are [[polyploid]] so mating aggregates do not occur. Therefore only chain formation and flocculation are of relevance to the brewing industry.

[[Cell aggregation]] occurs throughout [[microbiology]], in [[bacteria]], [[filamentous algae]], [[fungi]] and [[yeast]] (Lewin, 1984; Stratford, 1992). Yeast are capable of forming three aggregates; mating aggregates, for DNA exchange; chain formation, for development and differentiation; and flocs as a survival strategy in adverse conditions (Calleja, 1987). Brewing strains are [[polyploid]] so mating aggregates do not occur. Therefore only chain formation and flocculation are of relevance to the brewing industry.

Flocculation is distinct from [[agglomeration]] (‘grit’ formation), which is irreversible and most commonly in bakers yeast strains of fail to separate when resuspended (Guinard and Lewis, 1993). Agglomeration only occurs following the pressing and rehydration of yeast cakes and both flocculent and non-flocculent yeast strains have been shown to demonstrate agglomeration (Guinard and Lewis, 1993). It is also distinct from the formation of biofilms, which occur on a solid substrate.

Flocculation is distinct from [[agglomeration]] (‘grit’ formation), which is irreversible and most commonly found in bakers yeast strains, which fail to separate when resuspended (Guinard and Lewis, 1993). Agglomeration only occurs following the pressing and rehydration of yeast cakes and both flocculent and non-flocculent yeast strains have been shown to demonstrate agglomeration (Guinard and Lewis, 1993). It is also distinct from the formation of biofilms, which occur on a solid substrate.

[[Pasteur]] first described flocculation of brewer’s yeast in 1876 (Pasteur, 1876) which has since been the subject of many reviews (Stewart et al, 1975; Stewart and Russell, 1986; Calleja, 1987; Speers et al, 1992; Stratford, 1992; Jin and Speers, 1999, Smart, 2001). Flocculation has been defined as the reversible, non-sexual aggregation of yeast cells that may be dispersed by specific sugars (Burns, 1937; Lindquist, 1953, Eddy, 1955; Masy et al, 1992) or EDTA (Burns, 1937; Lindquist, 1953). The addition of nutrients other than sugars has been demonstrated not to reverse flocculation (Soares et al, 2004). This is as opposed to mating aggregates formed as a prelude to sexual fusion between complimentary yeast cells (Calleja, 1987; Stratford, 1992).

[[Pasteur]] first described flocculation of brewer’s yeast in 1876 (Pasteur, 1876) which has since been the subject of many reviews (Stewart et al, 1975; Stewart and Russell, 1986; Calleja, 1987; Speers et al, 1992; Stratford, 1992; Jin and Speers, 1999, Smart, 2001). Flocculation has been defined as the reversible, non-sexual aggregation of yeast cells that may be dispersed by specific sugars (Burns, 1937; Lindquist, 1953, Eddy, 1955; Masy et al, 1992) or EDTA (Burns, 1937; Lindquist, 1953). The addition of nutrients other than sugars has been demonstrated not to reverse flocculation (Soares et al, 2004). This is as opposed to mating aggregates formed as a prelude to sexual fusion between complimentary yeast cells (Calleja, 1987; Stratford, 1992).