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Streif J.,Kompetenzzentrum Fur Obstbau Bodensee
Acta Horticulturae | Year: 2010

Fruit ripening is a highly regulated process with coordinated genetic and metabolic events, leading to essential changes in gene expression, physiology, biochemistry and anatomy. These complex regulatory events transform a physiologically mature but inedible fruit into an edible, tasty product. Innovations in CA technology like dynamic controlled atmospheres (DCA) and/or the use of the chemical ethylene inhibitor (1-MCP) are new tools for the enhancement and preservation of quality and health promoting components in climacteric fruit. Dynamic CA, with non-destructive monitoring systems based either on ethanol concentration or chlorophyll fluorescence allows the use of oxygen atmospheres during storage that are close to the lowest tolerance limits for fruit without inducing excessive anaerobic metabolism. In contrast to other available technologies, 1-MCP has the potential to control ethylene action by blocking the ethylene receptors and thereby maintaining fruit quality, and avoiding specific storage disorders not only in storage but also during marketing and shelf-life. Sensory investigations and consumer expectation surveys have confirmed that aroma, firmness, crispiness and juiciness are the most relevant sensory traits. Ripening regulation by modern storage technology shows great benefits in terms of texture, total soluble solids (TSS) and acidity but often hampers aroma formation mainly depending on the at-harvest ripening stage of the fruit. In future, postharvest researchers will be challenged to meet consumer requirements with fruit that is well flavoured and nutritious.

Xuan H.,Kompetenzzentrum Fur Obstbau Bodensee | Spann D.,Kompetenzzentrum Fur Obstbau Bodensee | Neumuller M.,TUM
Acta Horticulturae | Year: 2013

Twenty-six apple and two pear SSRs were initially chosen as fingerprinting markers for quince. Eleven apple SSRs were discarded due to inadequate production of alleles. The remaining 15 apple and two pear SSRs generated a total of 65 alleles and were used to fingerprint a subset of 19 quince cultivars. The number of alleles per locus ranged from 2 for CH02b10 and CH03g06 to 6 for CH03d01, NZ02b1 and CH04e03 with an overall mean of 3.8 alleles per locus. Gene diversity (PIC) for the 17 SSR loci varied from 0.29 to 0.78. The primer pair CH05a04 was the most informative and CH02b10 the least informative. Based on the PIC values, nine of the primers: CH05a04; CH04e05; CH05d08; CH03d01; CH04e03; CH03g12; CH02c06; Nz02b1 and NH029a are suggested for use in fingerprinting quince cultivars.

Neuwald D.A.,Kompetenzzentrum Fur Obstbau Bodensee | Streif J.,Kompetenzzentrum Fur Obstbau Bodensee
Acta Horticulturae | Year: 2012

Molecular biology techniques are developing rapidly and can now be used as assays to help determine the optimum harvest date for fruit crops. While molecular assays are still more expensive and time consuming than the conventional maturity tests currently used for apples they offer a number of potential advantages, in particular the possibility to detect changes in fruit ripening processes at a very early stage and perhaps in the near future to help predict storage quality outcomes. To adapt a new methodology for practical use requires trialling and comparison with existing methods. When results from different seasons and apple cultivars are available, the suitability and reliability of molecular methodology can be better understood and assessed. This work compares conventional methods for optimum harvest date determination with the genetic testing service, supplied by the Dutch based Company 'Nsure'. The 'Nsure' test measures the expression of genes with relevance to some of the key ripening processes in maturing apples. In 2008 and 2009, three apple cultivars: 'Gala', 'Fuji' and 'Braeburn' from the Lake Constance growing region of Germany were sampled three times in the period leading up to harvest and two times from unpicked trees after the expected optimum harvest date. The conventional ripening parameters: fruit firmness, total soluble solids and starch degradation pattern were used to calculate a 'Streif' ripening index and the optimum harvest date for long term storage. In addition, samples for the respiration rate, ethylene production and internal ethylene were taken. Gene expression at each sampling date was evaluated by 'Nsure' Company. The results from both methods were compared.

Neuwald D.A.,Kompetenzzentrum Fur Obstbau Bodensee | Kittemann D.,Kompetenzzentrum Fur Obstbau Bodensee | Streif J.,Kompetenzzentrum Fur Obstbau Bodensee | Andrade C.A.W.,University of Sao Paulo
Acta Horticulturae | Year: 2012

Apples with severe watercore are rejected during market quality control inspections because affected fruit can develop alcoholic off-flavours and internal browning symptoms. This work investigates post-harvest temperature conditioning treatments before long term CA storage and ripening inhibitor or promoter treatments to accelerate watercore dissipation without excessive loss in fruit firmness. Late harvest 'Fuji' apples with severe watercore were kept in air at 1°C (2008), 3°C (2007), 6°C and 10°C (2007, 2008). Some fruit at 10°C were also treated with 1-MCP and Ethephon. In 2009, fruit were held in CA at 1, 3, 6°C and in air at 10°C. Additional treatments were 1-MCP 24 h after harvest or non-treatment followed by the respective storage temperatures. Changes in flesh firmness and watercore were followed during 6 months storage. Fruit at 1, 3°C in air and fruit at 10°C treated with 1-MCP showed nearly no change in flesh firmness while untreated fruit in air softened by 0.8 kg/cm2 at 6°C and around 1.0 kg/cm2 at 10°C. Watercore in 'Fuji' apples with and without 1-MCP or with ethephon treatments at 10°C dissipated to acceptable levels after around 16 to 22 d, while apples at 1, 3 and 6°C showed acceptable watercore at 51, 29 and 26 d, respectively. When 'Fuji' apples have severe watercore at-harvest, one option is to treat them with 1-MCP and store in air at 10°C for 20 d before CA storage, thus watercore levels will reduce rapidly but fruit flesh firmness will generally be maintained at acceptable levels. After 3 weeks a significant dissipation in watercore was observed in fruit stored at 3, 6 and 10°C, with the higher temperature treatments negatively correlated with watercore levels. Due to decreases in fruit quality, by either softening and/or decay incidence, storage at 10°C in air without 1-MCP should not be more than 2 and 4 months with 1-MCP, and no more than 4 mths at 6°C without 1-MCP while 1 and 3°C were unsuitable for 6 months storage without 1-MCP. 1-MCP treatments showed similar effects to the use of CA storage in the maintenance of firmness. Watercore did not increase the occurrence of other internal physiological disorders.

McCormick R.,Kompetenzzentrum Fur Obstbau Bodensee | Kittemann D.,Kompetenzzentrum Fur Obstbau Bodensee | Streif J.,Kompetenzzentrum Fur Obstbau Bodensee
Acta Horticulturae | Year: 2010

1-methylcyclopropene (1-MCP) is a potentially valuable tool to improve the postharvest quality of apples during commercialisation. The sensory (organoleptic) quality of 1-MCP treated apples is strongly influenced by the at-treatment ripeness stage, storage conditions, and storage duration. This investigation evaluates the consumer preferences for riper and less-ripe 1-MCP treated 'Elstar' apples after two storage periods. The apples were commercially stored for 4 months in CA plus 8 d shelf life at 20°C (January 2007 consumer test) and 8 months CA plus 8 d shelf life (May 2007 consumer test). In January, shoppers preferred the less-ripe untreated and ripe 1-MCP treated 'Elstar' apples while less ripe 1-MCP treated and ripe untreated fruit were clearly non-preferred. But in May after 4 further storage months, the consumer preference pattern had changed and less ripe 1-MCP treated fruit were now clearly preferred while ripe untreated fruit showed very low preference scores. These consumer preference test results show that 1-MCP treated 'Elstar' can under some circumstances (e.g., short term CA storage with less ripe fruit) be non-preferred. Optimal post-harvest management after the introduction of 1-MCP now requires producers and postharvest operators to be even more diligent to match fruit ripening with storage conditions and consumer marketing windows.

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