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Avocado Quality Program

Targets for industry performance in eating quality

From a combination of past consumer research and anecdotal evidence, three areas of quality have been identified as particularly significant in terms of importance for providing consumer satisfaction. They are internal quality, maturity and ripeness.

Internal Quality

A consumer sensory project was completed in 2007.  One of its three main objectives was to determine the maximum acceptable level of internal defects at different price points above which future consumer purchasing decisions are negatively influenced.  To understand this, the consumer survey that was presented to consumers in a panel situation provided the panel members with a picture of avocados with different levels of severity of internal damage caused by bruising and presented scenarios of different prices and different rates of incidence.

The other two objectives of the study related to maturity and ripeness which required actual fruit to be viewed and tasted which is why a consumer panel was used rather than other available methods such as an online or postal survey.

Using consumer panels however did limit the range of scenarios that could be presented to panel members (with regard to internal quality) which meant only one type of internal defect could be included (bruising) and also limited the sample size.  Because photos could be used to communicate internal damage to the panels there was therefore the opportunity to expand the sample size for internal quality by using an online survey in a future project.

An online Consumer Quality Survey was subsequently conducted in 2008. The project involved the development of an online survey whose main objective was to extend the findings of the 2007 study to determine the impact of price, incidence and severity of defect on consumer intention to purchase avocados using three of the most commercially significant quality defects i.e. bruising, stem end rot and vascular browning. 

The results from both studies indicated that severity of defect had the largest impact on future purchase intentions

The results from the first sensory panels indicated that the levels and incidences of defect (bruising) that will reduce consumers’ purchase intent below ‘probably buy’ (i.e. 70% to 89% probability of purchase) varied depending on price: However for any price above $1.29 if more than 10% of flesh was damaged this would put purchase intent below “probably buy” even though there were some slight variations depending on incidence levels.

For all three defects subsequently tested in the online survey the pattern of responses was consistent with the relative importance discussed above, which showed that severity of defect was of primary importance.  For all the defects, respondents reported a higher likelihood of purchase for a slightly affected fruit (10% of unusable flesh) even if experienced every time (five out of five occasions), compared with a severely affected fruit (50% unusable flesh) experienced very infrequently (one out of 10 occasions), and this occurred at all price points. 

It was also found that Increases in price will decrease tolerance to defective fruit, particularly at lower levels ($0.89 to $1.39) and higher levels ($1.99 to $2.49). This effect was not so significant when price changed from $1.39 to $1.99 which suggests that there is a subconscious affect when the price changes from within one dollar value to another i.e. from one dollar something to two dollars something even if the actual price rise is the same amount.

Based on the research it was recommended that because increases in severity of defect will have the greatest negative impact on future purchase intentions of avocado consumers  steps should be taken at all steps in the chain to ensure that damage to fruit is at an absolute minimum.

Maturity

Based on anecdotal evidence the industry has been aware for a long time that avocado maturity is an issue in terms of internal quality and although there has been an industry standard of 21% dry matter which was loosely adhered to by industry there was very little evidence available to support a link between that standard and consumer acceptability.  Consequently a review of harvest indices and how they relate to postharvest quality was initiated.

It was recommended, based on the results of this project that the industry review of the minimum maturity standard (21%) should be carried out in the light of the significantly higher standards in other countries, and in particular the suggested move of California from 20.8% to 23%.

One of the main objectives of the Consumer sensory project  was to determine the minimum maturity measurement as measured by % Dry Matter that produces ‘Hass’ avocados which are of acceptable eating quality to Australian consumers.  The testing was conducted using consumer sensory panels.

Based on the results of this project it was recommended that a minimum DM% for Hass avocados be set at 23% to ensure an appropriate competitive advantage in the market place.  With support from industry a new standard of 23% at time of harvesting has therefore been set.

Ripeness

Consumer sensory research was conducted in 2007 to determine the level of ripeness (firmness) that is preferred by consumers at the time of consumption.

Avocado firmness (ripeness) can be measured using a range of tools including penetrometers (an invasive tool that measures flesh firmness) and firmometers (a non invasive tool which measures the firmness of the whole fruit through the skin).  Hand firmness ratings are also used (although this is only a reliable measure if trained staff conduct the tests and even then regular calibration is needed).  

Consumers who tasted avocados indicated that on average the fruit that were about 1.05 kgf (using penetrometer with 11 mm probe) firmness were significantly less liked, less likely to be purchased and less acceptable than fruit that were 0.65 kgf or 0.45 kgf. Avocados from these two softer firmness categories were not significantly different from each other according to any of the consumer responses measured (see graph below). This firmness level usually relates to Firmometer value of about 80 and a hand firmness of about 5 (i.e. whole fruit deforms with moderate hand pressure).

Figure 1: Purchase Intent for Avocados of Different Ripeness Levels

This result was important in providing the industry with information regarding what state of ripeness fruit should be displayed at and also at what level of ripeness it is most relevant to measure for quality.

Resulting targets in eating quality

After consideration of the results and recommendations of these projects and taking into account industry knowledge of what the industry will bear in terms of quality benchmarks it has been determined that a premium grade Hass avocado must be:

• 23% dry matter or above (a maximum may be determined at some point in the future)
• Be of ripeness level somewhere between 0.65 kgf and 0.45 kgf
• Have no more than 10% damage to flesh.

Retail Quality Monitoring
In 2008 a project to survey avocado retail quality was developed to measure how much fruit at the retail end fulfilled consumer’s quality demands. The project also measured where there were significant differences in quality, between store types, growing regions and/or seasons. This project provides the second part of the equation needed to benchmark the industry against consumer expectations.

The quality surveys involve testing for internal quality at the retail level and testing for Dry Matter percentage (as a measure of maturity) at the wholesale level.

Quality surveys are conducted in four capital cities including Sydney, Brisbane, Melbourne and Perth. In each city, 16 stores are surveyed on a monthly basis. 0, 10 or 15 pieces of fruit, depending on the availability of ripe fruit (including both Hass and Shepard when available) are sampled from each store and tested for percentage of overall damage and then proportions attributable to specific types of damage.

The Dry Matter surveys are also conducted monthly with fruit collected from the Sydney Wholesale Markets and tested for Dry Matter percentage in Maroochydore, Queensland.

Results up until July 2011 show that overall internal quality in both Hass and Shepard has improved since the program began in 2008. In summary the program results include:

• Incidences of internal defects had a significant association with sampling month, state, and store type of purchase
• When the results were analysed in conjunction with the consumer sensory research conducted in 2007 it could be determined that the cheaper fruit have a higher predicted probability of purchase. However the cheaper fruit also had the larger estimated reduction in purchase probability due to defects. The graph below illustrates this relationship in NSW stores.Figures 2 and 3 below represent the change in proportion of fruit that has more than 10% internal damage to the flesh.

Figures 2 and 3 below represent the change in proportion of fruit that has more than 10% internal damage to the flesh.

Figure 2: Proportion of Hass with more than 10% internal damage

Figure 3: Proportion of Shepard with more than 10% internal damage

Up until 2010 bruising was always the most significant quality issue however in 2010 a reduction in the level of bruising resulted in the overall level of damage decreasing and the significance of bruising as the cause of internal damage reduced below body rots for the first time. Figure 4 shows that the proportion of Hass avocados with more than 10% bruising to the flesh has decreased by 50% between 2008 and 2010 from 12% to 6%. Figure 5 shows that this is now less than the proportion of Hass avocados with more than 10% damage due to body rots. The most significant improvements have been made in New South Wales (NSW) and Victoria (VIC).

Figure 4: Proportion of Hass with more than 10% specific internal defects 2008 – 2010

Figure 5: Proportion of Hass with more than 10% of specific defects by year

In Shepard avocados, bruising is still the most significant issue (as shown in Figure 6) with the reduction in body rots being the largest contributing factor to the overall reduction in internal damage. Figure 7 shows that bruising actually increased very slightly between 2009 and 2010 although not nearly to the levels it was at in 2008.

Figure 6: Proportion of Shepard with more than 10% specific internal defects 2008 - 2010

Figure 7: Proportion of Shepard with more than 10% of specific defects by year

In terms of store type, the data has been summarised into four store type groupings; Major Supermarket 1 (M1), Major Supermarket 2 (M2), Independent Supermarkets (IS) and Independent Fruit and Vegetable Stores (I). The results indicate that both supermarkets have improved levels of total damage, independent supermarkets have had the least improvement and consistently the highest level of damage and independent fruit and vegetable stores have always had either the lowest or second lowest level of damage.

This is consistent when looking at bruising specifically in Hass avocados. M1 performance was variable; bruising levels improved significantly in 2009 but started to worsen again in 2010. M2 has shown the most improvement. Again independent supermarkets had the least improvements.

Figure 8: Hass with more than 10% total internal damage by store type 2008 - 2010

Figure 9: Proportion of Hass with more than 10% bruising by store type 2008 - 2010

To date only 6 months of data had been collected for the 2011 season therefore it is not possible to compare this data against 2008, 2009 and 2010, however it is possible to compare overall monthly total damage levels for each month by year. See figures 10, 11, 12 and 13 below.

Figure 10: Proportion of Hass with more than 10% total damage by month/year

Figure 11: Proportion of Hass with more than 10% total damage by year/month

Figure 12: Proportion of Shepard with more than 10% total damage by month/year

Figure 13: Proportion of Shepard with more than 10% total damage by year/month

When the results from the first 12 months of the program were analysed in conjunction with the consumer sensory research conducted in 2007 it could be determined that the cheaper fruit have a higher predicted probability of purchase. However the cheaper fruit also had the larger estimated reduction in purchase probability due to defects. Figure 14 below illustrates this relationship in NSW stores.

Figure 14: NSW Probability of Avocado Repurchase

In terms of Dry Matter testing, the common theme with all of the results is that Dry Matter are generally more of an issue at the beginning of each growing region’s season. As the season progresses and fruit becomes more mature Dry Matter increases.

Figure 15 shows the amount of time it takes each region to supply 100% of their fruit at 23% or above for Hass.

Figure 15: Time taken for Growing Regions to Supply 100% of Hass at 23% DM or Above

Figure 16 shows the amount of time it takes North Queensland and Central Queensland to supply 100% of their fruit at 21% or above for Shepard. Obviously because the Shepard season is much shorter than the Hass season, the data is only able to be collected for a few months at a time.

Figure 16: Time taken for North Queensland and Central Queensland to Supply 100% of Shepard at 23% DM or Above

In combination with the previous consumer research this work has provided the industry with objective data with which to go to specific supply chain partners and measure the bottom line impact of maintaining the status quo in terms of quality versus implementing practices to improve quality.