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Subject: search.filters.subject.Postharvest diseases and injuries

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    An investigation of the loss in value attributable to bruising for the postharvest handling system of apples : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Agricultural Systems and Management at Massey University
    (Massey University, 1997) Jackson, Hamish
    Bruising has been identified as one of the major sources of harvest and postharvest fruit damage in New Zealand operations. Using Porter's (1985) value system as a framework, a model was developed to investigate the value of apples lost due to bruising from harvest to ship-side, in the Hawkes Bay District. The cost of bruising was identified using the model for the apple varieties Braeburn, Fuji, Granny Smith, Pacific Rose , and for both large and small packhouse based operations. The initial problem statement was developed by applying the "rich" pictures approach which is part of Checkland's (1975) soft systems methodology. To achieve the research objectives, two case studies based on three orchards and two packhouses were investigated to model the value system for apples. The first case study involved two large orchards supplying a large commercial packhouse that packed more than 350,000 TCEs per season. The second study involved a small orchard, that supplied its own on-orchard packhouse, which packed less than 100,000 TCEs per season. Two value systems were developed for the fruit handling systems of the two case studies. An important factor in calculating the value of fruit on the orchard was the inclusion of an allowance for the grower's return on equity. The value system began once the on-orchard costs of producing apples, including operating costs, fixed costs and return on equity (set at 20%), were covered. Once the initial value of fruit had been established, commercial rates for picking, trucking, and other steps in the processing and distribution chain, were used to establish the value system. This approach enabled the losses attributable to bruising to be costed. Losses increased through the system steadily and were greatest at the market end of the value system than on the orchard. Losses due to bruising, up until and including packing, were found to be much higher for the grower than for any other participant in the value system. This was because the grower forfeited export earnings, as well as paying the direct costs of producing and handling reject fruit. For the Braeburn, Fuji, and Pacific Rose , varieties the total cost of 1% bruising was equivalent to approximately a 3% loss in export earnings. The loss in value attributable to bruising for Pacific Rose was more variable due to limited amount of data available collected. The total cost for 1% bruising of the most bruise susceptible variety, Granny Smith, was estimated to exceed 4% of export earnings. The total loss to the growers of the apple industry needs to be minimised to ensure the growth of the industry. Since the growers are suffering high losses of returns and small, if any, return on equity due to fruit bruising, it is unlikely that the growers can afford to invest in strategies that can reduce bruising. If new strategies are to be implemented, the returns need to surpass the investment made. Keywords: Value system, Porter process, bruising, fruit value.
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    Prediction and quantification of apple bruising : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Agricultural Engineering at Massey University, Palmerston North, New Zealand
    (Massey University, 1993) Pang, David Weilong
    Mechanical handling subjects fruit to impacts which often cause bruising. Such bruising is a major source of quality loss in the fruit industry. In this study, a range of experiments was carried out to investigate the quantification of bruises and the prediction of bruising in relation to mechanical handling systems. In order to understand apple bruising, a study of free normal impact between pairs of apples was conducted. There was a 2/5 power relationship between contact area and impact energy. The coefficient of restitution varied in a non-linear manner with impact energy, decreasing as impact energy increased. Bruise damage produced by a typical New Zealand-made fruit grader was critically analysed. A large percentage of individual bruises was under 1 cm2 in area and it was rare to have any bruises above 3 cm2. The total number of bruises was found to be the best indicator of bruise susceptibility. A new method of predicting such bruises has been developed involving a new term, the Bruise Factor, which was related to bruising sustained during handling operations, allowing for the variation in fruit size, shape and mass. An Instrumented Sphere (IS) was used to characterize impacts on commercial packing lines. It was found that the IS could be used to identify apple-to-apple impacts likely to cause bruising in commercial packing operations, providing care is taken with interpretation of the data. Typical impacts on packing lines were represented by impacts onto a flat steel surface, a rubber pad, a plastic tube, a solid plastic bar, and onto another fruit. Impact tests were conducted on freshly picked Gala, Splendour, Fuji, Braeburn, and Granny Smith apples, all grown in Hawkes Bay, New Zealand. Bruise areas produced by impact onto flat steel, rubber, plastic tubing, and a solid plastic bar were found to be linearly correlated with the peak acceleration recorded by an Instrumented Sphere dropped from the same heights. Following fruit-to-fruit impacts, bruising was generally more severe on one of the two apples. When the results of apple-to-apple and IS-to-apple impacts were compared, it was found that the area of the larger of the two bruises produced in fruit-to-fruit impacts was directly related to the peak acceleration recorded by the IS when it was dropped onto a fruit from the same height. For each variety and each surface the drop height required to produce a critical bruise with a surface area of 1 cm2 (as measured with the skin removed) was determined. By joining the threshold points on each surface response line, a threshold potential bruise boundary was formed on a velocity change against peak acceleration graph. The boundary curve, which included apple-to-apple impact, was hyperbolic in shape, rather than the linear boundary described in other studies. The implications of the results to the fruit industry are discussed in this study.