Night-working. Long hours worked at night were the main factor that set baking apart from other crafts. Night working was promoted both by the consumer (wanting to purchase fresh bread before work in the morning) and the supplier (the journeyman working on commission, who needed to buy the amount of flour agreed with the miller or corn factor). The introduction of the free market encouraged longer hours and during the nineteenth century, bakers might have only 4-5 hours sleep each day.
Yeast - bread-making was a lengthy process, needing to take into account the cycles of rising and kneading. Until the production of dried yeast, it needed to be nurtured as a living product, in the forms of barm or ferment - which remains true of traditional sourdough bread. In 1859 the aerated bread process, which needed no yeast, was patented by Dr John Daulish, founder of The Aerated Bread Company. This reduced the length of time taken in breadmaking from around 10 hours per loaf to around 2 - but the high costs of the machinery limited its take-up.
Perishability - this limited bread production to the locality and required consumers to make regular purchases.
In a fascinating article on the Halifax (Canada) baking and confectionary industry, we found a quotation from an 1868 petition by the Journeyman Bakers' Friendly Society "To the Master Bakers of Halifax", which puts the workers' hours of labour into a social and moral context designed to resonate with public opinion on respectability.
In a moral and intellectual point of view it is nearly as bad, as we have no time for recreation, no moral improvement; no time to spend in the social or family circle. We have no time for the public meeting, lecture, concert or religious duty; the Sun shines in vain for us, the trees and plants may grow, and the flowers may bloom, but not for us. To us the delights of the country are a sealed book; to prepare for our early toil we have to go to bed, (those that have one), while the rest of the world is awake, and work while the rest of the world asleep, thus reversing the laws of nature. No wonder that some of us have recourse to stimulants in order to give a spur to our overworked and failing nature, and for the time to bury in oblivion our degraded position.'
Burnett, J., 'The Baking Industry in the Nineteenth Century', Business History, 5/2 (1963), pp.98-108
Collins, E.J.T., 'Food adulteration and food safety in Britain in the 19th and early 20th centuries', Food Policy, 18/2 (1993), pp.95-109
Decock, P. and S. Cappelle, 'Bread technology and sourdough technology', Trends in Food Science & Technology, 16/1-3 (2005), pp.113-20
Gourvish, T.R., 'A Note on Bread Prices in London and Glasgow, 1788-1815', The Journal of Economic History, 30/4 (1970), pp.854-60
McKay, I., 'Capital and Labour in the Halifax Baking and Confectionary Industry during the last half of the Nineteenth Century', Labour/Le Travail, 3 (1978), pp.63-108
Ross, A.S.C., 'The Assize of Bread', The Economic History Review, 9/2 (1956), pp.332-42
Stern, W.M., 'The Bread Crisis in Britain, 1795-6', Economica, n.s. 31/122 (1964), pp.168-87
University of Durham, Special Collections and Archives, 'Bread through the Ages', available at http://www.dur.ac.uk/~dul0www3/asc/bread/control1.htm
Webb, S. and B., 'The Assize of Bread', The Economic Journal, 14 (1904), pp.196-218