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Abstract

The terminology used to describe developmental stages of fruits is often confusing or even misleading. “Mature” and “ripe” are often used synonymously. We find reference to “green” fruit, based on skin or peel color, used interchangeably with “unripe”, the latter without referring to pigmentation but rather to a state of non-palatability. We see in the literature such words used synonymously as “overripe” and “senescent” in describing a fruit in a very late stage of development. Such terms as “early maturity”, “optimum maturity”, or “full maturity” leave some doubt as to what stage is actually under consideration. At best, different authors are not always referring to the same stage, even when dealing with the same fruit.

Open Access

Maturity standards that determine when navel oranges can be harvested in California are currently based upon the ratio of soluble solids content (SSC) to titratable acidity (TA) and the rind color of the fruit. These standards may be inadequate to describe the quality of the fruit, which is important given the increased competition from other commodities in the marketplace and declining consumption of fresh citrus. To reevaluate the basis of the maturity standard, navel oranges were harvested at intervals throughout the season and evaluated for SSC, TA, juice ethanol concentration, percent juice, peel coloration, and sensory characteristics. Three varieties of navel oranges, representing early-, mid- and late-season maturities, were used. SSC: TA ratios averaged 6.3 at the beginning of the season and steadily increased to 23.4 at the end of the season. Changes in the hedonic rating, or likeability of the fruit taste as rated by the sensory panelists, were closely related to the SSC: TA ratio and ratings of sweetness and tartness. These relationships showed a similar pattern for all of the navel varieties. A hedonic rating of 6 (like slightly) was not reached until the SSC: TA ratio exceeded the current legal minimum of 8:1, suggesting that the standard should be raised. Juice ethanol levels and percent juice did not have any apparent influence on the sensory ratings. Fruit that were run over a packing line and waxed developed higher amounts of ethanol during storage than control fruit but did not differ substantially from them in hedonic rating.

Free access

Effects of fertilizer application levels on fruit texture and flesh pectin compositions of a melting peach were investigated. Hakuho trees (Prunus persica Batsch) were supplied with normal (M), high (H; M × 2), and superhigh (SH; M × 4) levels of complete liquid fertilizer twice a week. Flesh firmness of the H and SH treatment fruit was lower than that of M treatment fruit at the hard-mature and firm-mature stages, although no difference was detected at the full ripe stage. Sensory scores for flesh texture at the full ripe stage were highest in the N treatment fruit and lowest in the SH treatment fruit. The content of water-soluble polyuronides (WSP) in flesh was highest in SH fruit and lowest in M fruit at the hard-mature stage, although the difference became smaller at the full ripe stage. Molecular mass analysis using a gel filtration column revealed that water-soluble polysaccharides in alcohol-insoluble solids (AIS) of the H and SH fruits had a peak of high molecular mass, ≈200 kDa, at the hard-mature stage, and the molecular mass decreased gradually to ≈23 kDa at the full ripe stage. In the M fruit, however, the molecular mass was rather constant during the ripening period, 112 kDa even at the full ripe stage. The analysis of acidic fractions (pectin) in the polysaccharides using an ion exchange column, as well as juice gellation test by adding Ca and Tris buffer, also indicated that high levels of fertilizer application impairs an early degradation of flesh polyuronides resulting in the accumulation of low-molecular-weight WSP. This may ultimately cause the inferior flesh texture of overfertilized peach fruit.

Free access

Abstract

A 500 ppm gibberellin A3 (GA) spray applied shortly after full bloom to unemasculated peach flowers caused some fruit to develop parthenocarpically. Nonparthenocarpic fruit sprayed with GA were similar to parthenocarpic fruit in their elongated shape and advanced maturity, and dissimilar to unsprayed control fruit. The applied GA, rather than a lack of ovule development, is therefore primarily responsible for alterations in shape and maturity of parthenocarpic peaches.

Open Access

Changes in rind firmness and cell wall polysaccharide composition were measured in fruit with a) a soft rind, (`Satsuma' mandarin, Citrus unshiu Marc., cv. Aoshima), and b) a firm rind (hassaku, C. hassaku Hort. ex Tanaka), from August to January of the following year. Rind firmness was similar in both species in August, but hassaku had significantly firmer rind than did mandarin from September to January. Both flavedo and albedo tissues were extracted, and the extracts were hydrolyzed and fractionated to yield four fractions: (hot water, EDTA, hemicellulose, and cellulose). In flavedo tissue, sugar concentration was highest in the cellulose fraction, and lowest in the hemicellulose fraction. The concentration in all fractions decreased as the fruit developed and matured. Although the sugar concentration in the cellulose and EDTA fractions of both species was similar in August, it was significantly higher in both fractions in hassaku than in mandarin in January. The sugar concentration of each fraction from albedo tissue was in the order: cellulose > hemicellulose > hot water > EDTA. The range of variation in cell wall sugars in albedo tissue was smaller than that in flavedo tissue. Chemical name used: ethylenediaminetetraacetic acid (EDTA).

Free access

Abstract

Seeds of freshly harvested American ginseng (Panax quinquefolius L.) were stratified at 5°, 10°, 15°, 20°, or 25°C for 6, 8, 10, 12, 14, or 16 weeks. Regardless of the duration of stratification, respiration was usually lowest at 5° and highest at 20°. For temperatures ≥15°, respiration increased with time, reaching a maximum at week 14 and decreasing thereafter. Measurable embryo growth was not detected at 5° and 10°, but at temperatures ≥15°, growth was observed beginning at week 10. By week 16, the greatest embryo growth was attained at 15°, while the greatest percentage of actively growing embryos occurred at 20°. Changes in embryo length closely paralleled those for the embryo: endosperm length ratio. Delaying the initiation of stratification after seed extraction by as little as 10 days reduced embryo growth.

Open Access

Muskmelon (Cucumis melo L.) seed crops sometimes contain seeds with split coats that expand to twice their normal water content. These expanded seeds are often referred to as “fishmouth” seeds, because the split seed coat resembles an open fish's mouth when viewed longitudinally. “Fishmouth” seeds are dead seeds. However, little is known about why death occurs inside the fruit before harvest. Hermaphroditic flowers were tagged at anthesis and fruits were harvested at various intervals during the later stages of development and decay. Seeds were removed from the fruits and incubated in water on germination blotter paper for 14 days. The percentage of germinable, dead and “fishmouth” seeds were averaged for each Harvest date. Fruit pericarp samples were analyzed for pH, ethanol, and acetic acid content. At 50 days after anthesis (DAA), just past edible maturity, 100% of the seeds germinated. However, at 60 and 78 DAA germination dropped to 60 and 17%, respectively, while the occurrence of “fishmouth” seeds increased from 2 to 54% over the same period. The ethanol content of the tissue increased from 0.11 to 0.28%, the pH dropped from 6.2 to 5.1, and acetic acid concentration increased from 3.0 to 3.7 mM from 50 to 60 DAA, respectively. However, when dried seeds were incubated in the laboratory under conditions similar to those within the fruit, the formation of “fishmouth” seeds was related to the ageing effects of long term hydration and was not correlated with any chemical product within the fruit.

Free access

Physiological disorder occurred in a recently developed oriental melon cultivar, `Gumssaragi-Bunchun' (Cucumis melo var. makuwa), is involved with the appearance of water soaking area in placenta and can be extended to the pulp when severely affected. Physiological changes between normal and disordered fruits were compared. Ethanol soluble sugars were significantly decreased in both pulp and placenta tissue of disordered fruits whereas acidity was increased. Ethanol and acetaldehyde accumulation were confirmed in juice from disordered fruits, which were net detectable in normal ones. The contents of boron and calcium, especially water and HCl soluble calcium, were fairly low in disordered pulp. Also, there was a great difference in pectin content between both fruit tissue and severe hydrolysis of water soluble pectins isolated from disordered placenta was found by gel chromatography. However, the hydrolysis of pectins seemed not to be associated with the increase of wall hydrolase activities such as polygalacturonase and β-galactosidase.

Free access

Chilling accumulation infuence dormancy of grapevines and determines budbreak. Under desert conditions, hydrogen cyanamide (H2CN2) improve bud opening. To increase even further the quantity and uniformity of bud break, the effect of fall evap rative cooling (EC) alone or in combination with H2CN2(2.5%v/v was evaluated. Microsplinklers operated for 40 seconds at 10 min intervals from 10:00 h to 17:00 h, from 20 oct to 18 dec 1990. H2CN2 was applied on 21 dec, one day after pruning.

Cyanamide treated plants or with the chemical + EC, had 19% and 32% budbreak, respectively, by jan 15. Control or EC vines opened until feb 20, and reached 40% and 57% final values by mar 25. Therefore, cyanamide and EC acted sinergisti cally to open buds earlier and uniformily, although not on final budbreak.

Harvest started may 8 with cyanamide + EC, five days earlier than cyanamide alone; by may 13, accumulated harvest was 39% and 13% respectively, and of 92% and 77% by may 28. Control vines with or without EC, were harvested early may to mid june.

Free access

A likely reason why consumers are not repeat buyers of many fresh-cut fruit is inconsistent or unsatisfactory flavor and/or textural quality. Research toward understanding mechanisms responsible for generation, and/or loss of flavor compounds in fresh-cut fruit is limited. Solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) were utilized to study flavor volatile profiles in anthesis-tagged cantaloupe (Cucumis melo L. var. reticulatus Naud. cv. Sol Real) during growth, development, and for fresh-cuts prepared from fruit with five distinctly different harvest maturities. One-quarter-slip fruit had a clearly green, well-attached peduncle; 1/2-slip fruit had a distinct abscission detectable at the peduncle, 3/4-slip fruit were approaching commercial harvest, full-slip (FS) fruit are or will cleanly separate from the vine with light pressure; and over-ripeness (OR) was precisely categorized as 2 days past FS. Recovery of total volatiles displayed a linear response and most volatile classes (except aldehydes) generally followed a trend upon processing where FS > 3/4-slip > 1/2-slip > 1/4-slip. On day 0, only 70.0%, 37.7%, and 20.5% total volatiles were recovered in 3/4-slip, 1/2-slip, and 1/4-slip fruit, compared to FS fruit. During fresh-cut storage, percent total esters followed an increasing linear trend that was maturity-dependent. Percent total aromatics and percent aldehydes followed a linear trend that was maturity-dependent whereby 1/4-slip > 1/2-slip > 3/4-slip > FS. During storage, the relative percentage of acetates decreased, and displayed a maturity-dependent curvilinear trend. The magnitude of the slope decreased with maturity, indicating that the effect of storage time decreased as maturity increased. In FS, 3/4-slip, 1/2-slip, and 1/4-slip cubes, acetates comprised 66.9% of all compounds recovered on day 0 yet, only 26.1% to 44.2%, and 21.3% to 32.6% remained on days 9 and 14, respectively. For all maturities, a curvilinear increase in relative percentage of nonacetate esters was observed during storage. There was a uniform change in the ester balance (nonacetate ester:acetate ratio) during fresh-cut storage, which was independent of initial processing maturity. The overall ester ratio changed roughly 2-fold after just 2 days in optimum storage, and after 5 days it increased more than 3-fold. The shift in endogenous ester compounds could be partially responsible for the apparent loss of characteristic flavor in fresh-cut cantaloupe through long-term storage.

Free access