Grapefruit (Citrus paradisi Macf.) were sampled biweekly from importers in Rotterdam, the Netherlands, from Oct. 1992 through Sept. 1993. For each sample, fruit size, weight, peel thickness, internal pulp color, juice weight, total soluble solids (TSS), and total acid (TA) were measured. Three grapefruit cultivars—`Marsh' white, `Ruby Red', and `Star Ruby'—were sampled from 12 countries of origin. Florida fruit weighed more, had the thinnest peel, the most juice, the lowest TA, and the highest TSS/TA ratio for all three cultivars compared to all other origins, except for `Ruby Red' grapefruit from California, which had a lower TA and a higher TSS/TA ratio. Turkish `Ruby Red' and Spanish `Star Ruby' fruit weighed the least and had the least amount of juice compared to fruit from other origins. Turkish fruit had the highest TA and the lowest TSS/TA ratio for all three cultivars from all origins. Israeli `Marsh' white and `Star Ruby' had the highest TSS. Overall, the internal quality characteristics of Florida fruit was high compared to fruit from other origins.
L.A. Risse and A.J. Bongers
L.A. Risse and R.E. McDonald
Quality changes of supersweet corn (Zea mays L.) were monitored during storage at 1, 4, or 10C, unwrapped or wrapped in stretch or shrink film. Film-wrapping maintained freshness and reduced moisture loss better than lack of wrapping. Wrapping in shrink film resulted in lower O2 and higher CO2 concentrations within packages than wrapping with stretch film. Film-wrapping in shrink film maintained total soluble solids content better than stretch-wrapping or no wrapping.
Jeffrey K. Brecht, Steven A. Sargent, and L. A. Risse
Snap beans were room cooled (RC) or forced-air cooled (FA) in a 4.5°C commercial cold storage room, or hydrocooled (HC) in a commercial flume-type unit with 4°C water containing 175 ppm NaOCl. The beans were packed in wirebound wooden crates (WC) or waxed corrugated fiberboard cartons (FC) before (RC, FA) or after (HC) precooking and stored one week at 10°C before evaluation. Ascorbic acid, chlorophyll and fiber contents did not differ among treatments, while moisture content and per cent unshrivelled beans were lowest in FA and highest in HC, and lower in WC than in FC containers. HC reduced development of mechanical damage symptoms (browning) and decay compared to RC and FA. The former effect was attributable to the presence of NaOCl rather than leaching or increased cooling rate in HC. HC beans packed in FC had the highest per cent sound beans and lowest per cent beans showing mechanical damage symptoms of all the treatment combinations tested.
R. E. McDonald, L. A. Risse, and B. M. Hillebrand
Strains of Penicillium digitatum (Sacc.) and P. italicum (Wehmer) resistant to thiabendazole and benomyl were isolated from decaying citrus fruits obtained from the Rotterdam, Netherlands, terminal market and originating from 18 countries. Significantly more Penicillium sp isolates with resistance to thiabendazole and benomyl were collected from grapefruit and lemons than from oranges. Significantly more isolates of P. digitatum than P. italicum grew on agar plates with 4, 10, or 40 ppm thiabendazole. A greater percentage of P. digitatum than P. italicum isolates grew on 4 and 10 ppm benomyl-agar plates, but a greater percentage of P. italicum than P. digitatum isolates grew on 40 and 80 ppm benomyl-agar plates. Both species were more resistant to thiabendazole than to benomyl, and often showed cross-resistance to the fungicides. Resistant Penicillium sp isolates produced larger colonies on 4 and 10 ppm thiabendazole and 40 and 80 ppm benomyl.
W.R. Miller, D. Chun, L.A. Risse, T.T. Hatton, and R.T. Hinsch
`Thompson' pink grapefruit (Citrus paradisi Macf.), waxed or film-wrapped, treated with thiabendazole (TBZ) or untreated, were used to determine the effect of high-temperature conditioning at 31C for 3 days on fruit during subsequent storage for 4 weeks at 1 or 10C. Chilling injury (CI) developed in all conditioned fruit stored at 1C, but was drastically reduced in film-wrapped compared to waxed fruit. Thiabendazole slightly reduced CI, and fruit held at 10C had fewer CI symptoms than those held at 1C for 4 weeks. Conditioning Florida grapefruit at 31C for 3 days did not allow subsequent storage at 1C without rind discoloration. Chemical name used: 2-(4'-thiazolyl)-benzimidazole (thiabendazol, TBZ).
L.A. Risse, J.K. Brecht, S.A. Sargent, S.J. Locascio, J.M. Crall, G.W. Elmstrom, and D.N. Maynard
Two newly released cultivars of small watermelons [Citrullus lunatus (Thumb.) Matsum and Naki], `Mickylee' and `Minilee', plus two other cultivars, Baby Fun and Sugar Baby, were stored at various temperatures from 1 to 21C for up to 4 weeks plus 1 week at 21C over two seasons. All cultivars were susceptible to chilling injury (CI) when stored below 7C; however, `Minilee' was less susceptible than the other cultivars tested. Chilling injury increased with storage length. Conditioning at 26C for 3 days before storage at 1C reduced CI and increased the percentage of marketable watermelons after storage. Decay percentage increased with storage time and was highest on fruit held at 1C where CI led to decay. The flesh of `Mickylee' and `Minilee' was firmer than that of the other cultivars tested and `Mickylee' and Minilee' retained their firmness better during storage. Total soluble solids concentration decreased with increased storage temperature. `Minilee' watermelons were superior to the other three cultivars in postharvest storage potential and exhibited the least CI and decay.
T. T. Hatton, R. H. Cubbedge, L. A. Risse, P. W. Hale, D. H. Spalding, D. von Windeguth, and V. Chew
Seven irradiation tests (with exposures of 0, 7.5, 15, 30, 60 and 90 krad) were conducted on 26 lots of grapefruit throughout the 1981–82 and early 1982–83 citrus seasons. Fruit treated with 60 and 90 krad showed rind breakdown and scald after storage for 28 days at optimum temperatures. Scald was the dominant injury in early-season fruit in tests conducted during Oct. and Dec. 1981 and Sept, and Oct. 1982. Rind breakdown, especially pitting, was the dominant injury in all other tests with midseason and late-season fruit. At the 7.5-, and 15-, and 30-krad exposures, injury was minimal, and fruit exposed to these dosages were acceptable. Although some 60- and 90-krad exposures resulted in excessive injury, 2 tests at 60 and 90 krad were acceptable with early fruit. In some instances, injured areas developed decay after storage and marketing conditions at 21°C.