Clingstone Peach Research Articles

DIFFERENCE IN POLYGALACTURONASE COMPOSITION OF CLINGSTONE AND FREESTONE PEACHES

ABSTRACTThe composition of polygalacturonase activity and the solubility of pectin were compared in clingstone and freestone peaches. At the unripe stage, all varieties of both types of peaches had low levels of water‐soluble pectin and virtually no polygalacturonase activity. Ripe clingstone peaches had exopolygalacturonase activity and essentially insoluble pectin. Ripe freestone peaches had exopolygalacturonase and endopolygalacturonase activity and high levels of water‐soluble pectin. These differences in composition of polygalacturonases may account for the markedly different textural characteristics of the two types of peaches.

Gas chromatographic and sensory analysis of volatiles from cling peaches

Gas chromatographic and sensory analysis of volatiles from cling peaches

Peach Harvest System Optimization Model

ABSTRACT A Mixed Integer Programming model is presented for choosing an optimal peach harvest system. This linear model will produce solutions for four ob-jective functions: maximizing benefit and minimizing labour, capital and energy. The solutions are subjected to several con-straints reflecting factors involved in peach harvest management such as price received and quality of peach-es, weather and timeliness, and labour and energy re-quired to harvest. The optimal solutions presented are based on input data pertinent to average Southern Ontario conditions, for 50, 125, 250, 375, 500, and 1 000 t of clingstone peaches harvested annually. For these conditions, the break-even point between handpicking and machine harvesting is approximately 110 t. The picking opera-tion itself accounted for about 90 percent of the total cost of harvesting with bin handling and transportation accounting for the rest.

Consumer Acceptance of Mississippi and California Non-melting Cling Canned Peaches1

Abstract Canned non-melting cling peaches (Prunus persica (L.) Batsch) from a California commercial-pack rated higher than those grown and packed in Mississippi for flavor, texture, and appearance but 90% of consumers rated both samples in the 3 “liked” categories.

Mechanical harvesting of clingstone peaches

A new self-propelled harvester for Clingstone peaches is described. Design features include a low profile, a single-unit construction, decelerator strips over most of the catching area, a trunk-type shaker and independent front-wheel and rear-wheel steering for good manoeuver-ability. Field testing was conducted on 7 Clingstone peach varieties to evaluate machine performance, tree damage, fruit removal, fruit maturity, fruit damage and economics. Machine performance was judged to be very good. Fruit quality was nearly equivalent to that obtained by hand harvesting and the cost of machine harvesting was found to be competitive with that of hand harvesting.

Comparison of two methods for determining the vitamin A value of clingstone peaches

Comparison of two methods for determining the vitamin A value of clingstone peaches

Studies on the epidemiology of peach rosette and decline disease in Victoria

The spread of peach rosette and decline dlsease (PRD) was studied in two clingstone peach orchards, located 24 km apart in the Goulburn Valley of Victoria. Over 11 years the incidence of diseased trees in an orchard of cv. Golden Queen increased from 0.9 to 91.5%, while in an orchard of cv. Pullar's Cling the proportion of diseased trees rose from 1.5 to 29.6% over 5 years. The apparent infection rates were identical in both orchards over the first 5 years of the two epidemics.In both orchards, a significantly higher proportion of healthy trees growing adjacent to previously diseased trees became infected in subsequent seasons. This pattern of spread of the disease is discussed in relation to pollen transmission of the viruses and the foraging habits of bees. The spread of PRD was reduced by 29.4% over 2 years by the grubbing of all visibly diseased trees before flowering in a planting of cv. Golden Queen. Removing the flowers from diseased trees at the 'pink bud' stage also reduced the rate of spread of the disease by 13.8% in 1 year. Removing newly diseased limbs at the crotch of the tree within 4 weeks of flowering, however, did not prevent the spread of the disease into the rest of the tree.

Microwave Thawing of Peaches A Comparative Study of Various Thawing Processes

AbstractThe purpose of the present paper was to determine the influence of various thawing treatments of microwaves and of the air temperature (air 20° C; air 20° C then 4° C) on the exudation of Clingstone peaches, peeled or not, in relation to the stage of maturity. The amount of exudate, its content of total sugars and the fruit browning to the end of thawing were measured. We have previously shown that thawing by microwave energy promotes both a good retention of the water and of the substances dissolved in the cells and a better preservation of the structure and color of the fruits.

Relationship of Maturity as Indicated by Flesh Color to Quality of Canned Clingstone Peaches

Clingstone peaches (cultivars Babygold 5 and 7) ranging in maturity from unripe to over-ripe were classified according to flesh color into 10 maturity groups, using a Hunterlab D25P Color Difference Meter. The canned peach halves were graded on the basis of color. texture and flavor by an expert panel. Maturity affected the quality of the canned peach halves. Canning improved the color of unripe peaches. The maturity groups giving the best quality canned products were those with Hunter aL readings of 4.0 to 6.0 for the raw flesh color of Babygold 5 and 10.0 to 12.0 for that of Babygold 7. The average drained weight of canned halves of the less mature peaches was lower than that of the more mature.

The Role of Ethylene in Abscission of Cling Peach Fruit

Ethylene production was measured in fruit of a number of cling peach cultivars within 1 h of picking. During the period when ethylene production on the tree was rising exponentially, fruit from cultivars with low preharvest drop produced ethylene at much lower rates than fruit from high-drop cultivars. Also, the ethylene peak tended to occur earlier relative to flesh colouring in high-drop cultivars. The level of endogenous ethylene controlled the rate of abscission, which was retarded by holding the fruit in an atmosphere of 15% CO*2. Abscission was accelerated by injection of (2-chloroethyl)- phosphonic acid, but the cultivars Golden Queen and Phillips, and an unnamed cultivar, differed from each other in their sensitivity.

A Method for Selecting the Optimum Maturity Distribution for Mechanical Harvesting of Clingstone Peaches for Processing1

Abstract High speed reflected light spectrophotometry was used to determine an optimum maturity distribution of mechanically harvested clingstone peaches (Prunus persica (L.) Batsch) for processing. Succinic acid-2,2-dimethylhydrazide (SADH) applied at pit-hardening, advanced the optimum harvest date from 3 to 5 days and increased the yield of processable fruit from 62% for the control trees to 80% for the treated trees.

Antitranspirants to Size Peaches and Replace Preharvest Irrigation1

Abstract A firm-forming antitranspirant sprayed on trees of ‘Halford’ and ‘Vivian’ cling peach [Prunus persica (L.) Batsch] 1-2 weeks before harvest, increased fruit growth and substituted for a preharvest irrigation. Such replacement of the final irrigation can enable timely entry of harvest equipment to the orchard, unhampered by a wet soil surface, without a reduction in fruit growth.

EFFECTS OF RIPENESS AND POST-HARVEST TREATMENTS ON THE FIRMNESS, ACIDITY AND CANNING CHARACTERISTICS OF BABYGOLD #6 PEACHES

Effects of ripeness and post-harvest storage on firmness, acidity, and canning characteristics of southeastern non-melting clingstone peaches (as represented by the cultivar Babygold #6) were investigated. Best results were obtained from ripe peaches harvested at 90 to 100% ground color development and canned without further holding. Firmness values of the raw fruit increased one day after harvest but diminished steadily during 10 days storage at 24 and 1 C. Total acidity of raw peaches diminished during storage after harvest. At 24 C the rate of decrease was uniform between 3 and 14 days. However at 1 C the rate of change decreased with increased storage time. Firmness of the canned halves was influenced by ripeness and post-harvest storage. Ripe fruits, and those stored at 1 C, had lower canned product firmness values. Viscosity values of the canned peach syrup and total grade scores were markedly influenced by storage temperature and time. The reduced acidity in Babygold #6 peaches stored for more than three days and canned resulted in a low-acid food in terms of thermal processing conditions.

Textural Changes in Ripening Peaches

Clingstone and freestone peaches of varying degrees of ripeness were subjected to a puncture test, a modified G. F. Texture Profile, and a set of rectangular punches that enable a compression coefficient (Kc), and a shear coefficient (Ks), to be evaluated. Adhesiveness and viscosity were absent in the G. F. Texture Profile. Cohesiveness was constant for clingstone peaches although the two areas whose ratio is the cohesiveness parameter decreased at the same rate as the puncture test. The other textural properties: fracturability, hardness, elasticity, chewiness, Kc, and Ks decreased at about the same rate as the puncture test. Correlation coefficients between these textural parameters and the puncture test were all significant. This leads to the conclusion that almost any kind of textural property can be used successfully as an index of textural quality of fresh freestone or clingstone peaches because the various textural parameters change in the same direction and at approximately the same rate as the fruit rlpens. The results also indicate that compression (Kc), is the major contributor to the puncture reading and that shear is a minor contributor.

Leaf analysis survey of Pullar's Cling peach trees in northern Victoria: correlations between leaf nutrient status and tree performance in two years

The N, P, K, Ca, and Mg contents of mid-shoot leaves of ten-year-old Pullar's Cling peach trees in the Goulburn Valley Irrigation Area, and the associated Murray Valley Irrigation Area were surveyed in 1964 and 1965. Leaves were sampled in mid summer from healthy trees in 73 orchards distributed over five major fruit-growing districts, and the results were related to tree yield (fruit number,) and vigour (butt circumference). Multiple regression analysis of the survey data showed that between 30 and 40 per cent of the total variation in tree yield over the two-year period was accounted for by variation in tree nutrient status. Such results clearly indicate the degree of influence that nutrition can play in the performance of mature peach trees in the field. As judged by published leaf nutrient standards for peach trees, about two-thirds of the peach orchards were of low nitrogen status in both seasons and this situation was reflected in tree yield. The low nitrogen status of the trees overall was a reflection of the low average amounts of nitrogenous fertilizer applied per tree per year. One-fifth of the orchards were of low phosphate status, but tree performance was not adversely affected as a result. In single years also, significant correlations were recorded between leaf K, leaf Ca, and tree performance, but, overall, these results were difficult to interpret meaningfully.

Effect of Phloroglucinol and Resorcinol on the Clingstone Peach Polyphenol Oxidase-catalyzed Oxidation of 4-Methylcatechol

Phloroglucinol and resorcinol are not substrates for clingstone peach (Prunus persica) polyphenol oxidase, but they react with 4-methyl-o-quinone, produced either enzymatically or nonenzymatically, to give an intense red or red-brown color with a maximal absorption at about 470 nanometers. Several colored products were isolated from an ethyl acetate extract of the reaction by two-dimensional thin layer chromatography. Based on thin layer chromatographic and spectral studies of the enzymatic and nonenzymatic reactions, polyphenol oxidase does not play a role in the reaction between 4-methyl-o-quinone and phloroglucinol, resorcinol, d-catechin, or orcinol. In such reactions, the function of polyphenol oxidase is the formation of 4-methyl-o-quinone which then reacts nonenzymatically with the above phenols. Activation energies of both enzymatic and nonenzymatic reactions were determined.

Isolation and Characterization of Polyphenol Oxidase Isozymes of Clingstone Peach

The polyphenol oxidase system in clingstone peach (Prunus persica) was investigated. Polyacrylamide disc-gel electrophoresis indicated four bands with polyphenol oxidase activity in extracts from acetone powder of clingstone peach. These four isozymes were then isolated from a buffer extract of peach acetone powder by cold acetone precipitation, followed by diethylaminoethyl cellulose column chromatography. All isozymes had different heat stabilities. At 55 C, polyphenol oxidases A, B, and D had half-lives of 5.4, 14.6, and 14.1 minutes, respectively. Polyphenol oxidase C was stable over a period of 50 minutes of incubation at 55 C, but had a half-life of 2.2 minutes at 76 C. None of the isozymes had monophenolase activity, and they varied in their specificity for several diphenols. The following values were found for polyphenol oxidases A, B, C, and D, respectively, with catechol as substrate: optimal pH: 6.8, 6.5, 7.2, and 7.0; Michaelis constant: 6.6, 4.2, 7.0, and 36 mm; V(max)/(E(0)): 4.95, 39.4, 2.16, and 80.0 (DeltaA min(-1) mg(-1)). Each isozyme showed a different amount of inhibition by NaHSO(3), NaCl, NaCN, l-ascorbic acid, glutathione, ethylenediaminetetraacetate, and sodium diethyldithiocarbamate.

CONSUMER RESPONSE TO COLOR IN CANNED CLING PEACHES

SUMMARY Mass consumer surveys for response to color in canned cling peaches were conducted at the 1965 and 1966 Royal Agricultural Shows in Melbourne. Fruit samples of the three peach varieties, representing pale‐yellow (9L4), medium‐orange (9L6) and deep‐orange (9L8) colored fruit, were viewed by 2808 individuals visiting the Government Pavilion during the 9‐day show. The medium‐orange colored fruit was liked significantly (P<0.01) better than deep‐orange, and highly significantly better than pale‐yellow fruit. The pale‐yellow fruit was disliked by 51–56% (16% undecided) of the people who participated in the tests. Significant interactions were evident among abode, sex and fruit color.

The Effect of 2-Chloroethylphosphonic Acid (Ethephon) on Maturation of a Processing Peach1

Abstract Ethephon applications at 250 to 1500 ppm rates during final swell of ‘Babygold-9’, a clingstone peach, accelerated maturation as measured by firmness and skin and flesh color changes and reduced titratable acidity. High rates were phytotoxic and detrimental to fruit quality. Increased immature fruit abscission appears to limit the practical use of ethephon at this growth stage in peach.

AN EXPERIMENTAL DRY CAUSTIC PEELER FOR CLING PEACHES AND OTHER FRUITS

SUMMARY– An experimental cling peach peeler was developed for continuous removal of alkaline peel as a solid rather than the dilute slurry of common industrial practice. The peeler consists of rows of soft rubber disks rotated in such a manner that peel material is gently wiped from the surface of fruit and flung into collectors. Cling peach halves were successfully peeled in a number of tests, with peeling losses comparable to those normally obtained commercially. Both mature and immature Bartlett pears were also successfully peeled. Dewaxing of immature pears with isopropy1 alcohol was necessary to obtain adequate peeling. In single tests, whole apricots and freestone peaches were also successfully peeled.