Green mathematics: Benefits of including biological variation in your data analysis
Biological variation is omnipresent in nature. It contains useful information that is neglected by the usually applied statistical procedures. To extract this information special procedures have to be applied. Biological variation is seen in properties (e.g. size, colour, firmness), but the underlying issue is almost always to the variation in development or maturity in a batch of individuals generated by small scale environmental differences. The principles of assessing biological variation in batches of individuals are explained without putting emphasis on mathematical details. Obtained explained parts increase from about 60 to 80 % for the usual approach to 95 when the biological variation is taken into account. When technical variation or measuring error is small even 99 % can be achieved. The benefit of the presented technology is highlighted based on a number of already published studies covering the colour of apples during growth and storage and the firmness of cut tomatoes during storage.
The impact of biological variation on postharvest population dynamics
Abstract This paper outlines a mathematical approach to the interpretation of postharvest batch behaviour based on the underlying processes occurring at the level of the individual food items and on the amount of biological variation present. This technique opens the door to a mechanistic interpretation of postharvest batch behaviour, both qualitative and quantitative, enabling the postharvest industries to improve their control of the quality of their produce throughout the postharvest chain. The generic approach is outlined and applied to case studies on shrivelling of ‘Braeburn’ apples, the colour change of ‘Hass’ avocados and stress crack development in corn grains.
Inhibition of senescence in broccoli florets with ethanol vapor from alcohol powder
A simple and cost-effective ethanol vapor treatment using alcohol powder, which gradually diffuses ethanol vapor, was conducted to inhibit the senescence of harvested broccoli (Brassica oleracea L. var. Italica) and to clarify the mechanism for the maintenance of the green color in the florets. Six branchlets were placed in a polyethylene bag with 0, 3, 6, or 12 g of alcohol powder and stored at 20 °C in darkness. The untreated broccoli florets started to turn yellow at 3 days in storage (DIS). The broccoli florets treated with 3 and 6 g of alcohol powder finally turned slightly yellow at 5 DIS. The yellowing was inhibited with 12 g of alcohol powder over a 5-day storage period. Ethylene production of untreated broccoli was highest at 2 and 3 DIS; after that, it decreased. However, in broccoli treated with alcohol powder, ethylene did not increase. 1-Aminocyclopropane-1-carboxylic acid (ACC) contents in untreated broccoli florets increased gradually, whereas in those treated with alcohol powder contents increased dramatically at 4 DIS. ACC oxidase activity in untreated broccoli florets also increased at 2 and 3 DIS, at the same time as the increase in ethylene production. There was no increase in those treated with alcohol powder. These results revealed that treatment with alcohol powder was effective for prolonging the shelf life of broccoli because it suppressed ethylene production by inhibiting ACC oxidase activity.