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  • Author or Editor: William J. Bramlage x
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Abstract

A new method for analyzing acetaldehyde concentration in apple (Malus domestica Borkh.) tissues was used to measure its accumulation in senescing fruits. Initially low levels (1 µg/g fresh weight) increased as the fruits ripened, but only at advanced senescence did they reach relatively high levels (14 µg/g fresh weight). Acetaldehyde did not accumulate in advance of tissue disorganization. Watercored ‘Delicious’ apple tissue accumulated significantly more acetaldehyde than tissue of non-watercored fruits during storage, but watercore breakdown did not result. There was no consistent difference in acetaldehyde levels of ethephon-treated and non-treated ‘McIntosh’ apples after long-term storage, although the ethephon-treated fruits developed more senescent breakdown. However, the acetaldehyde level in fruits after breakdown occurred was about 20% higher than that in corresponding sound fruit. Acetaldehyde accumulation appeared to be a consequence of tissue disorganization rather than a cause of senescent breakdown in the fruits.

Open Access

Abstract

Forecasting equations for predicting poststorage senescent breakdown from prestorage fruit Ca concentrations were developed for ‘McIntosh’ and ‘Cox's Orange Pippin’ apples using classical linear regression and the Tobit model. A comparison of the 2 regression methods was also made using 2 hypothetical data sets. Where the dependent variable was limited and a significant portion of the data was at the limit, as with ‘McIntosh’ apples, the Tobit model provided a superior forecasting equation. However, in cases where the dependent variable was not limited or it was limited and a significant portion of the data was not at the limit, as with ‘Cox's Orange Pippin’ apples, classical linear regression and the Tobit model produced similar forecasting equations.

Open Access

Diphenylamine (DPA) is applied postharvest to apples and pears to control scald development after storage. Using GC - MS analyses of hexane extracts of fruit surfaces, about 0.1 ug/g of DPA was measured on apples after 7 months of storage, even though no fruit in the storage were treated with DPA. Residues also were present on walls in the storage rooms. There is a report that DPA can be produced in plants. Therefore, fruit of 5 cvs. were harvested in mid-August and at commercial maturity and immediately extracted for measurement. A signal similar to that of DPA was detected in all extracts, but concentrations were too low for positive identification. Results show that presence of DPA residue on stored fruit is not proof that DPA was applied before storage. Extracts from freshly harvested fruit are being concentrated to try to ascertain the identity of the indicated material(s).

Free access

Abstract

A 4-year study compared 4 methods of subsampling ‘McIntosh’ apples for mineral analyses intended for use in predicting postharvest senescent breakdown. Concentrations of Ca, Mg, K, P, and N were determined in outer cortex, whole fruit, and juice in 1979 and 1980, and in outer cortex and cortical plugs in 1981 and 1982. Multiple linear regression equations were developed for each sampling in 1979 and 1981 relating the natural logarithms (In) of Ca and P concentrations and Mg:Ca, K:Ca, and N:Ca ratios to In (breakdown percentage +1). Effectiveness of each equation as a predictor of breakdown during and following storage was tested using data collected the following year. Paired t tests comparing predicted breakdown, using 1979 equations and 1980 mineral analyses, to breakdown observed after storage in 1980-1981 showed that outer cortex- and whole fruit-based predictions were not significantly different from observed breakdown, but juice equations predicted significantly more breakdown than was observed. Correlation coefficients relating actual to predicted breakdown were positive and significant for all 3 methods. In 1981, separate equations were developed to predict fruit breakdown after air and after controlled atmosphere (CA) storage. Paired t tests showed the predicted incidence of breakdown following CA storage was not significantly different from actual breakdown incidences for either outer cortex or cortical plug equations. Breakdown incidence following air storage was less than predicted. In all instances, correlation between actual and predicted breakdown incidence was positive and significant. Outer cortex, whole fruit, and cortical plug analyses showed promise as breakdown predictors, but juice analyses were ineffective.

Open Access

To examine the hypothesis that superficial scald of apple (Malus domestics Borkh.) is a chilling injury, `Granny Smith' apples were stored at temperatures ranging from 0 to 20C, temperature-conditioned before storage, and warmed during storage. Fruit stored at 0 or 4C developed supeficial scald. At 10C, surface defects occurred but they were not typical symptoms of scald, and at 15 or 20C no symptoms developed. Accumulation of α-1 faroesene and conjugated trienes in fruit peel correlated with increasing ethylene production, which was greater at higher temperatures. However, concentrations of conjugated trienes were highest at 0 and 4C. When fruit were kept at 10C for 5 or 10 days before storage, scald development after storage was not reduced. An interruption of 0C storage with a single warming period at 10 or 20C reduced scald development after 25 weeks of storage, maximum reduction occurring when fruit were warmed for 3 to 5 days at 20C after 1 to 4 weeks at 0C. Amelioration of scald declined as time at 0C before warming increased. Diphenylamine application after the same intervals at 0C, instead of warming, also was less beneficial as time before treatment increased. α-Farnesene and conjugated trienes increased during warming, but at the end of storage (when scald was developing) the conjugated triene concentrations in peel were reduced in fruit that had been warmed. Warming slightly increased yellowing, softening, and greasiness of fruit after storage, We conclude that chilling induced superficial scald on `Granny Smith' apples.

Free access

Abstract

Equations were developed that could predict the incidence of senescent breakdown, bitter pit, and decay in ‘Cox's Orange Pippin’ apples and senescent breakdown and bitter pit in ‘Bramley's Seedling’ apples. The parameters used to predict the incidences of disorders included fruit Ca, P, and K concentrations; fruit weight; respiration rate; and fruit maturity. Each disorder and each cultivar had a unique prediction equation. Such equations must be established individually for a disorder, cultivar, and, probably, growing region. Given an appropriate data base, this method seems to have broad applicability as a predictive tool for these disorders. However, core flush and low temperature breakdown could not be predicted using the parameters measured in this study.

Open Access

Abstract

In a 4-year study of the relationships between Ca, K, P, Mg, and N concentrations in ‘McIntosh’ apples at harvest and the quality of fruit after storage, Ca was the most variable element among samples within seasons and was the element most consistently related to disorders, being negatively correlated with senescent breakdown, rot, and scald. No element was correlated significantly with fruit firmness at harvest or after storage. Susceptibility of orchard lots of fruit to breakdown could be predicted from mineral analyses of fruit 2 weeks before harvest. An arbitrary scoring system incorporating all 5 elements was correct 69% of the time in identifying lots with high or low potentials for breakdown, but the middle range of scores was not closely related to breakdown potential. A regression equation was developed relating only Ca concentration in fruit at harvest with occurrence of breakdown after storage. This equation represented samples either stored in 0°C air for 5 months or in 3° CA storage for 8 to 9 months, and also represented samples taken in 2 different years. This equation was a better predictor of breakdown during storage than was the mineral scoring system, and we propose that such an equation could be used to predict storage potential for ‘McIntosh’ apples.

Open Access

Abstract

Fruit of equal size but varying Ca concentrations were harvested 4 times at weekly intervals for measurements of firmness, titratable acidity, soluble solids and starch, and of Ca, N, P, K, Mg, B, Fe, Mn, Zn, and A1 concentrations. In another experiment, fruit of 3 different sizes were measured generally as above. These measurements were compared with incidences of senescent breakdown, scald and rot after air storage at 0°C, and stepwise multiple linear regression was used to develop equations for predicting apple storage life. Among minerals and maturity indices, Ca, and starch concentrations, respectively, accounted for the most variations in senescent breakdown. Fruit diameter and fruit firmness also accounted for significant amounts of variation in breakdown after storage when fruit size varied. These results show that predictions of storage life based solely on mineral concentrations can be improved by incorporating maturity and size measurements at harvest when these factors are variable.

Open Access

When `Granny Smith' apples were stored at different temperatures, they produced different patterns of ethylene synthesis. Accumulation of α-farnesene and conjugated trienes (CT) in peel of these fruit paralleled ethylene production. Both pre- and postharvest applications of ethephon to `Cortland' apples increased accumulation of α-farnesene and CT, whereas application of DPA suppressed ethylene production and accumulation of α-farnesene and CT. When both ethephon and DPA were applied, their respective effects were negated. In these experiments, inhibition of ethylene synthesis always reduced scald development after storage, but stimulation of ethylene did not always increase scald development Ethylene had two effects: an immediate stimulation of α-farnesene and CT accumulation which increased scald susceptibility, and also a slowly developing alteration of CT metabolism, which reduced scald susceptibility. The effect of high ethylene on scald development depended on the balance between these responses.

Free access