Washington Tree Fruit Research Commission

Research Reports

Identification of procedures to extend ‘Honeycrisp’ storage life (2017)

FINAL PROJECT REPORT
WTFRC Project #
YEAR 0/0
Organization Project #
Title:Identification of procedures to extend ‘Honeycrisp’ storage life
PI:Jim Mattheis
Organization:USDA, ARS TFRL 509-664-2280 x 249 James.Mattheis@ARS.USDA.GOV 1104 N. Western Avenue Wenatchee, WA 98801
 PDF version of report

Co-PIs

Dave Rudell

USDA, ARS 

509-664-2280 x 245

david.rudell@ars.usda.gov

USDA, ARS

1104 N. Western Avenue

Wenatchee, WA 98801

 

Ines Hanrahan

WTFRC

509-669-0267

hanrahan@treefruitresearch.com

2403 S 18th Street, Suite 100

Union Gap, WA  98903

 

Cooperator

Tory Schmidt, WTFRC

 

Objectives

  1. Characterize differences in orchards that produce fruit with a history of disorder resistance or susceptibility.
  2. Determine utility of ethylene green life, fruit density, titratable acidity, chlorophyll fluorescence and chlorophyll absorbance as additional indicators of storability.
  3. Identify alternatives to the 7 day 50 oF pre-conditioning protocol.  
  4. Identify factors contributing to CO2 injury occurring during the initial 30 days after harvest.
  5. Identify CA protocols that maximize quality retention and minimize disorders.

 

Significant findings

Objective 1: Fruit from middle and low positions in v-trellis canopies displayed higher sensitivity to chilling injury in storage. Fruit position within the canopy influenced at harvest fruit quality to a greater extent than netting (except sunburn development). Netting of orchards led to changes in fruit quality after storage, most notably less bitter pit developed.

Objective 2: Ethylene green life varies with maturity at harvest and orchard lot.  Fruit chlorophyll fluorescence changes during cooling but is not an indicator of chilling sensitivity.  Fruit with high titratable acidity (TA) at harvest have relatively high TA after storage. The DA meter was able to track fruit maturation before picking, but did not correlate closely to other maturity indicators and did not pick up chilling injury development in storage.  Dry matter is poorly correlated with soluble solids content or other quality and disorder indicators at harvest and after storage.

Objective 3: Conditioning less than 7 days can enhance chilling injury.  Humidity during conditioning does not influence chilling disorder development.

Objective 4: High CO2 during 1-MCP treatment the day of or after harvest does not cause CO2 injury.

Objective 5: Bitter pit incidence can be reduced by CA and 1-MCP.  Incidence is reduced the most by 1-MCP treatment the day of harvest followed by CA establishment the following day while fruit is at 50 oF.  Total non-chilling disorder incidence is not enhanced by CA during conditioning.

 

Results and discussion

1.  Orchard factors: Fruit position in tree & light environment: Disorder incidence in storage was highly correlated by harvest sequence and location of fruit within the tree in all three years of the study. In particular, soft scald disorder sensitivity increased with advance in harvest date for fruit grown in the middle and lower parts of  the canopy, while fruit grown in top parts of the canopy exhibited soft scald, at times beginning with the second pick, but at much lower overall levels (Figure 1). Generally the first symptoms were observed after four weeks of forced cooling (chilling temperatures of 33°F), preferentially in lower parts of the canopy (example in Figure 2). Netting delayed the onset of soft scald, diminished the total amount expressed over time and evened out the canopy effect, i.e. symptoms expressed throughout canopy. (Fig. 1&2)

Figure 1: Development of soft scald in Honeycrisp apples stored for 12 weeks at 33°F. Fruit was harvested in 3 picks from three canopy positions from 2013 and 2015.

Figure 2: Time course of soft scald development in Honeycrisp apples stored for 12 weeks at 33°F in 2015. (Orchard 2, 3rd pick)

When storing fruit from netted and un-netted sections of Honeycrisp orchards, with or without 1-MCP application prior to CA establishment, we also found a marked reduction of bitter pit symptom expression in fruit grown under the 20% shade net, regardless of orchard or postharvest treatment (example in Figure 3).

Figure 3: Bitter pit expression of Honeycrisp apples after three months of cold storage; fruit grown in two orchards near Gleed, WA in 2014 with and without shade netting

We utilized the DA meter in all three years of the study to determine it’s utility to track maturity development, assess potential correlations to other common maturity indicators and non-destructively track fruit in forced chilling conditions to determine the DA meters capacity to detect chilling stress before visual symptoms appear on the fruit surface. As fruit matured on the tree, DA meter values decreased (as expected) and at harvest we typically observed a range of 1.2-0.5, depending on fruit position within tree (lower values in higher canopy positions).  (Table 1) Fruit grown in the top section of the canopy was generally redder, sweeter and more acidic (2015 example in Table 1), while starch degradation rates, background color change, fruit size, and DA meter values appeared to be more independent of position of fruit within the canopy. Netting sometimes affected single maturity parameters depending on orchard location and year, but most often, fruit from netted sections expressed maturity similar to fruit from unnetted sections (Example in Table 1). Examples of effects of netting on at harvest maturity form 2014 include: the lone maturity parameter affected by netting was higher colored fruit in the upper netted section as compared to the lowest untreated section in the first pick (2014); netted fruit had lower sugar concentration (2nd and 3rd pick) and higher DA meter values (2nd pick) (data not shown).

Table 1: Selected at harvest quality parameters for fruit from the third pick of two orchards near Gleed, WA partially covered by netting in 2015.

Netting of orchards consistently influenced the amount and severity of sunburn at harvest for all three years of the experiment (2015 example in Figure 4), thus significantly increasing the amount of packable fruit at harvest.

Figure 4: Sunburn incidence and severity in two Honeycrisp orchards at harvest in 2015.

2.  Harvest and postharvest factors.  Correlations among maturity and quality indicators at-harvest and at-harvest and after storage were evaluated particularly for dry matter and soluble solids content.  Correlations were low for dry matter and soluble solids content at harvest and after 4 months air storage (Figure 5), however, a high correlation existed for soluble solids content at harvest and after storage.  Results are for the first year of this comparison, additional results will be presented with the final oral report.  Notable in the dry matter – SSC comparison are the low SSC/high dry matter values for late harvest, poor quality fruit.  Harvest typically with most starch hydrolyzed may be a contributing factor to the relationships observed. 

Figure 5.  Relationship between fruit dry matter and soluble solids content at harvest and after storage.  Fruit were stored 4 months in air then 7 days at 70 oF. 

Initial ethylene production and rate of production increase may be indicators of storability.  Lower ethylene production is associated with earlier harvest but the production increase during a week at 70 oF is not always reflective of initial values (Fuller harvests 1 and 2; Figure 6).  Lower ethylene production is often associated with lower respiration rate and reduced utilization of titratable acidity, slower yellowing and greasiness development.