John Lopresti, researcher from Agriculture Victoria, introduces predicting fruit quality for stonefruit export, part of the Serviced Supply Chain project

Video transcript: Stonefruit Predicting Fruit Quality

As a component of the Serviced supply Chains project, we've developed flesh firmness and shelf life calculators for Australian stonefruit for growers and exporters, that are able to predict changes in quality and reminding shelf life along cold chains, either in domestic markets or during sea or air freight.

And these calculators are based on three factors. Harvest maturity as measured by harvest flesh firmness, the temperature, as well as the duration along each stage of the cold chain. And by inputting these numbers, we can look at different export and cold chain scenarios to get an understanding, to obtain an understanding of the changes in fruit quality, along the chain, depending on temperature management, as well as stage duration or stage period, as well as be able to estimate the remaining shelf life or fruit at various stages along the cold chain.

This will allow grower exporters to test some of their own export and cold chain scenarios and see what impact their temperature management and their handling of fruit, of stone fruit has on flesh firmness, fruit quality, and shelf life as it moves along cold chains.

A flesh firmness and remaining shelf life (RSL) calculator has been developed for ‘Majestic Pearl’ nectarine to demonstrate the benefits of comparing cold chain scenarios (temperature management and storage duration). This calculator will allow growers and exporters to test various cold chain scenarios of interest to them. It is intended that calculators will be further developed for up to six cultivars so that they can be used within an online dashboard that can be easily accessed by stone fruit industry participants.

On this page:

Background

A flesh firmness and shelf life calculator has been developed for stone fruit. The calculator is based on fruit quality data collected from a range of storage and simulated air and sea freight experiments over four years for ‘Majestic Pearl’ nectarine. This first version of the fruit quality calculator provides a prediction of flesh firmness and remaining shelf life (RSL) at various stages along the cool chain from harvest flesh firmness, storage and handling duration, and fruit temperature. For example, a grower, exporter, importer or retailer can use the calculator to determine RSL by assigning a preferred minimum target flesh firmness depending on their marketing requirements and minimum quality standards. The calculator can also be used to estimate RSL and flesh firmness for domestic cold chains, particularly where fruit is designated for cool storage prior to distribution and marketing.

Australian stone fruit growers and exporters will be able to access a non commercial version of the shelf life calculator for testing potential secarios -  for futher information contact John Lopresti:  (This calculator has been developed for Australian stonefruit producers and exporters only).

Users will be able to input their own fruit temperatures and stage durations for cold chain scenarios of interest, or applicable to their circumstances or markets, and obtain estimates of changes in flesh firmness or RSL, as a result of differing cold chain conditions.

It is envisaged that an online dashboard will be developed to predict RSL along cold chains for up to six stone fruit cultivars, incorporating the capacity to select one of two harvest maturities (i.e., pre-commercial and commercial maturity) per cultivar, as well as flesh firmness at harvest. In the future, it is hoped to develop dashboards that can utilise cold chain temperature data collected in ‘real-time’, allowing growers and exporters to track flesh firmness and RSL of monitored fruit, for example, whilst it is in cold storage, being exported, or being handled in the importing country by the importer or retailer.

In the following sections the features of the stone fruit quality calculator, and its potential to allow comparison of different cold chain scenarios, is demonstrated for both flesh firmness and RSL based on a simplified export cold chain as described in Figure 1. Although at present the calculator is based on data for ‘Majestic Pearl’ white-fleshed nectarine, the predictions generated by the calculator may be generalised to other white-fleshed nectarines for the purposes of comparing the effects of different cold chain scenarios.

Simplified export cool chain

Figure 1. Simplified export cool chain used within flesh firmness and shelf life prediction calculators.

Estimating flesh firmness along cold chains


The flesh firmness calculator can be used to estimate changes in fruit firmness along export cold chains incorporating five storage and handling stages (Fig. 2a & 2b). Users are required to input three parameters: average harvest flesh firmness in the blue cell of the calculator, stage duration in days (i.e., green font), and average stage temperature in °C (i.e., blue font). Once this information is typed into the relevant cells based on the cold chain scenario of interest, estimated flesh firmness will be calculated after each cold chain stage. Flesh firmness estimates assume that no storage disorders, such as chilling injury, develop in fruit along the cold chain, as it is known that storage disorders negatively impact on fruit flesh texture, slow fruit ripening, and thus will affect estimates of flesh firmness.

In the first example below, flesh firmness is estimated for ‘best’ case (A) and ‘worst’ case (B) sea freight export scenarios assuming a harvest flesh firmness of 8 kgf which is typical for white-fleshed nectarines of commercial maturity. In the ‘best’ case temperature management scenario (A), where stage durations are minimised (but still realistic), after 26 days of handling from harvest at 2 to 3 °C the estimated flesh firmness after sea freight is 6.5 kgf. In this scenario the importer only stores the fruit for two days and dispatches it for distribution to the retailer at 5.3 kgf firmness, with the consumer able to purchase fruit at the retailer with a fruit firmness of 3 to 5 kgf, assuming an average fruit temperature of 5 °C during distribution and retailing.

Scenario (A)
Figure 2a. Estimated flesh firmness

Figure 2a. Estimated flesh firmness for a ‘best’ case scenario (A) sea freight export chain.

Scenario (B)
Figure 2b. Estimated flesh firmness

Figure 2b. Estimated flesh firmness for a ‘worst’ case scenario (B) sea freight export chain.

On the other hand, in the ‘worst’ case scenario B, the sea freight stage duration has increased to 27 days, and importer storage to 7 days, with slight increases in importer and retailing average temperatures, resulting in an estimated flesh firmness of 3.9 kgf after sea freight, and fruit dispatched from the importer at a firmness of 1.4 kgf, which would allow little time for retailing, as fruit with a flesh firmness of 1 kgf or below are generally considered fully ripe. Among both scenarios there is little change in estimated flesh firmness during a ‘Harvest to freight forwarder’ duration of 5 or 7 days at 3 °C, with flesh firmness changes at low temperature only apparent after the relatively long sea freight stage.

Note that the uncertainty in the estimated flesh firmness will vary with handling stage, with the estimates for very firm (i.e., > 6 kgf) or very ripe fruit (i.e., < 2 kgf), likely to be more accurate than firmness estimates during importer storage and retailing, with approximate uncertainties of ± 0.5 kgf and ± 1 kgf, respectively.

In the second example below (Fig. 3a & 3b), flesh firmness is estimated for ‘best’ case (A) and ‘worst’ case (B) air freight export scenarios also assuming a harvest flesh firmness of 8 kgf at commercial maturity. In the ‘best’ case temperature management scenario (A), air freight temperature averages 8 °C for one day with no estimated change in average flesh firmness after air freight and minimal change in firmness during importer storage at 4 °C for 7 days. Even after a distribution and retailing leg of five days at 5 °C, average flesh firmness remains above 3 kgf, providing ample time for retailing and consumer purchase.

In the ‘worst’ case air freight scenario (B), both ‘Harvest to freight forwarder’ and ‘Importer storage’ stages are longer, with an air freight temperature of 14 °C. Interestingly even at this relatively high temperature, little change in estimated flesh firmness is observed after sea freight, but its consequences are clear after importer storage, combined with a slightly longer storage duration at 5 °C, resulting in a flesh firmness of less than 3 kgf prior to dispatch by the importer. Thus it appears that the negative impact of a short duration spike to a relatively high temperature during air freight is likely only to be observed after cool storage of more than one week.

Scenario (A)
Figure 3a. Estimated flesh firmness for a ‘best’ case scenario air freight export chain.

Figure 3a. Estimated flesh firmness for a ‘best’ case scenario (A) air freight export chain.

Scenario (B)
Figure 3b. Estimated flesh firmness for a ‘worst’ case scenario air freight export chain.

Figure 3b. Estimated flesh firmness for a ‘worst’ case (B) scenario air freight export chain.

Estimating RSL along cold chains


An alternative to estimating flesh firmness directly is to utilise the calculator to predict RSL along the cold chain. In the examples provided below, an importer or retailer can use previous stage temperature and duration data, (from ‘real-time’ temperature monitoring, if available) to estimate RSL, based on a selected minimum average fruit firmness at which point fruit must be dispatched (by the importer) or sold (by the retailer). Again, users are required to input three parameters: minimum flesh firmness before dispatch or sale is necessary (in the orange cell of the calculator), stage duration in days (i.e., green font), and average stage temperature in °C including importer storage temperature (or retailer stage temperature) (i.e., blue font) (Fig. 4). With this information in the relevant cells, RSL until fruit reaches the minimum allowable flesh firmness is estimated.

In the first example below, RSL is estimated as 4.9 days at an importer storage temperature of 2 °C for a ‘best’ case (A) sea freight export scenario including 23 days of sea freight, assuming the white-fleshed nectarine was harvested at commercial maturity and a minimum allowable flesh firmness prior to dispatch of 4 kgf (Fig. 4a & 4b). In a ‘worst’ case scenario (B) with the same minimum allowable firmness of 4 kgf and cool chain stage duration and temperature as scenario (A) but where the importer storage temperature is now 6 °C, estimated RSL has now reduced to less than two days, clearly demonstrating the effect on shelf life of sub-optimal storage temperatures.

Uncertainty in the estimated RSL will generally vary according to the number of cold chain stages prior to RSL calculation, with higher accuracy usually in estimates after sea or air freight and increasing uncertainty in RSL estimates after importer storage or retailing. Uncertainty in RSL estimates based on current fruit quality models is likely to be ± 1 to 3 days, with the larger uncertainty likely among later cold chain stages.

Scenario (A)
Figure 4. Estimated remaining shelf life during importer storage at 2 °C and 6 °C after sea freight.

Figure 4a. Estimated remaining shelf life during importer storage at 2 °C (A) after sea freight.

Scenario (B)
Figure 4b. Estimated remaining shelf life during importer storage at 2 °C and 6 °C after sea freight.

Figure 4b. Estimated remaining shelf life during importer storage at 6 °C (B) after sea freight.

An example of how the RSL calculator has been designed to provide useful information when recommended storage durations are exceeded and firmness thresholds reached is provided in Figures 5a and 5b. In cold chain scenario A, fruit have been stored at low temperature for 31 days between harvest and the end of sea freight, and although the importer has approximately one day to dispatch fruit based on a minimum firmness of 4 kgf, a warning has appeared in the RSL column indicating that the recommended ‘storage’ duration for this cultivar has already been reached, increasing the risk of storage disorders developing along the remaining cold chain. With this warning an importer may decide to dispatch the fruit immediately to minimise the potential for storage disorders. Note that the maximum recommended storage duration will generally be different for each cultivar.

If the storage duration from harvest through to the end of sea freight is below this maximum threshold then a ‘continue’ message will be displayed in the RSL column (cold chain scenario B). In this case the importer storage temperature is 4 °C, and at this temperature fruit will have virtually no shelf life prior to reaching a minimum firmness of 4 kgf, and thus the calculator will display a warning in the RSL column. In this situation, an importer may be able to reduce their storage temperature and potentially increase RSL by 1 or 2 days if they cannot reduce the minimum firmness threshold below 4 kg due to customer quality requirements or standards.

Scenario (A)
Figure 5a. Information provided by RSL calculator

Figure 5a. Information provided by RSL calculator warning that total recommended sea freight storage duration (A) has been exceeded resulting in an increased risk of storage disorders during importer storage and retailing.

Scenario (B)
Figure 5b. Information provided by RSL calculator

Figure 5b. Information provided by RSL calculator warning that minimum flesh firmness (B) has been exceeded resulting in an increased risk of storage disorders during importer storage and retailing.

In another example using the calculator to determine RSL during retailing (Fig. 6a & 6b), RSL is estimated at approximately 7 days (i.e., cold chain scenario A) after air freight at 10 °C and importer storage of one week at 4 °C, where an average temperature of 4 °C is assumed during distribution and retailing. In this case, RSL is based on a minimum threshold flesh firmness of 2 kgf and represents the threshold at which point fruit would be considered unmarketable to consumers. An increase in average retailer temperature from 4 to 10 °C as in cold chain scenario B (i.e., poor temperature management within this stage), demonstrates that RSL will fall from 7 days to approximately 3 days, giving the retailer little time to market the fruit.

Scenario (A)
Figure 6a. Estimated remaining shelf life during retailer handling

Figure 6a. Estimated remaining shelf life during retailer handling at 4 °C (A) after air freight and importer storage.

Scenario (B)
Figure 6b. Estimated remaining shelf life during retailer handling

Figure 6b. Estimated remaining shelf life during retailer handling at 10 °C (B) after air freight and importer storage.

The effect of changing the minimum flesh firmness threshold at which point the importer needs to dispatch fruit is demonstrated in the sea freight cold chain example provided in Figures 7a & 7b. In both scenarios A and B, stage temperatures and durations are the same, but minimum threshold firmness is set at 5 kgf in (A), and 4 kgf in (B), resulting in a corresponding increase in RSL for the importer from approximately 1 day (A) to 5 days (B). This example demonstrates how lower threshold firmness provides greater flexibility in terms of the marketing window. Of course whether the threshold firmness can be altered will depend on the marketing channel and on quality standards agreed to by the importer and retailer.

Scenario (A)
Figure 7a. Estimated remaining shelf life during importer storage after sea freight

Figure 7a. Estimated remaining shelf life during importer storage after sea freight with minimum flesh firmness allowable prior to dispatch set at 5 kg (A).

Scenario (B)
Figure 7b. Estimated remaining shelf life during importer storage after sea freight

Figure 7b. Estimated remaining shelf life during importer storage after sea freight with minimum flesh firmness allowable prior to dispatch set at 4 kg (B).

Webinar (27 min 22 sec)
Transcript: Webinar on predicting stonefruit quality during export

Now I want to look at impact of temperature management and storage duration on quality. And some of you might think hasn't all this kind of work been done before, we know the impact temperatures. Post harvest temperatures on fruit. My question to everyone is do we really? I don't believe we do.
We've got some general rules, higher temperatures speed up the rate of firmness loss that's about it as much as we know, and I'll show you that there's some interesting impacts of temperatures and sometimes they're unexpected. So the assumption is that we already know what the effects of temperature management and storage time is. But do we particularly for current export varieties, and we might have a general idea, but a lot of growers and exporters ask very detailed questions. What's the impact of a temperature spike during export on quality? Well, it's hard to say. Has anybody body really done the work? So these are some of the questions we might ask in terms of temperature management. What is, what is the actual impact of poor temperature management? So for example, three days at eight degrees Celsius during export, or 12 hours at 16 degrees during export? What is the real impact, for example, on fruit firmness of those spikes in temperature? An objective measure. Until we started looking at it, I couldn't find anybody doing that kind of work, especially for the cultivars we are growing. What is the impact of high airfreight temperatures on fruit quality? We always worried about temperature management in air freight, but what is the real impact? How long can a grower or importer cool store a variety before it won't ripen properly? That's what we're trying to find out. And what about directly after harvest? Do we cool down to low temperatures or do we delay cooling and do a bit of slow cooling after harvest? What's, and then what's impacted, if it's beneficial in longterm in terms of reducing storage disorders, what's impact on fruit softening, as well as impact of storage disorders?
So there are a lot of questions still to be answered, in terms of temperature management and our cultivars. So what we've done in our work over the last 3 years is we've looked at air freight and sea freight. What we've done is commercial simulation trials, exports simulation trials, because we've had seven dedicated cool rooms at different temperatures available at our Agriculture Victoria, Agribio centre in Melbourne. So we can basically try all sorts of export scenarios because we have access to those seven cool rooms that can be set at different temperatures. So it gives us a pretty good ability to simulate all sorts of export scenarios. And we can do two types. We can do constant temperature storage, say at two degrees for five or six weeks. And then ripen the fruit after each storage period. And as you see, that's an example for Diamond Pearl. Or we can actually simulate real commercial export scenarios, so your freight forwarder, your air or sea freight, the importer storage, distribution and retail, and there are the temperature within those stages in the export chain. So, it's a powerful ability to have, to actually simulate commercial practice. And what we've been doing is we've been, generally being using, through out trials, we've been using fruit packed for export and ready to go. And we pick up the fruit from the freight forwarder. So we are using fruit that is already destined for export markets. So our simulations are quite valid in terms of representing real world commercial practice and outcomes. So I will give you, I will demonstrate firstly for sea freight, some of the commercial export simulations we've conducted.  On the left here, this is for Flavour Pearl, and this one's Snowfall, which is a new, white peach, probably I think an early February, white peach and Flavour Pearl is a late December, I think, early January. And as you can see, we actually can simulate over, say a 30 and 40 day period, start of sea freights, simulate sea freight leg. End of sea freight. Then we can try different importer temperatures. I think this is about six days of importer storage, or a week at four degrees and 8 degrees. Simulate the effect and then effect retail at eight degrees here. And then the effect of ripening to say on, once the consumers purchase the fruit, how quickly there's a fruit ripened down to eating firmness.
So this is a ripening phase here. And as you can see, we can see the behaviours of each cultivar during export, based on temperature and we can vary the temperatures. And for example, snowfall here, and then, let me step back. These sea freight legs of 25, up to 30 days, these are not unusual as I've mentioned before. So we actually have been simulating long sea freight legs, because that's what we've found is happening commercially. And in this example, another, just something else to point out is that, so we've got importer storage at four, eight and 12 degrees. And as you would expect during importer storage, the fruit tends to soften more quickly at 12 degrees. But what's interesting is we noticed quite often that at the lower important storage, the firmness actually increases, which is not a good sign. It's indicating to us that at lower temperatures you are starting to get some mealiness and chilling injury, which is actually keeping the fruit quite firm. So we've noticed a spike in majestic Pearl and a few other cultivars. And again, something interesting we've noticed by being able to vary scenarios.
In terms of air freight, we've run two decent trials. And I'll show you, I'll show you some results from both of them. A few graphs here, but I'll take my time. They're pretty clear. Cut. Once you see what's going on. So this was airfreight simulation. What we did was we simulated air freight over 24 hour period, three different temperatures. So basically the period where, from the freight forwarder, onto the plane and then off the plane. And we simulated eight degree air freight temperature, a 12 degree and a 16 degree. That's a poor temperature management scenario, during air freight.
Polar Queen, a white peach, very susceptible to storage disorders, but nevermind. So the first graph here is what occurred in terms of flesh firmness with fruit that had no storage disorders. So clean fruit, good quality, all the way through to four weeks. And as you can see there was an effect of high air freight temperatures, which is 16 degrees, 12 and eight degrees. The 8 degree air freight temperature, well the fruit basically remained at four degrees over the four week storage periods, simulated importer storage remained pretty much at that, six to seven kilos firmness, whereas these air freight at high temperatures did impact on softening, as we would expect.  Although realistically, the importer wouldn't keep this fruit for longer than a week. And after wake at four degrees after air freight, there was a difference with the 16 degrees, but not really with a higher air freight temperature of 12 degrees. Eight to 12, probably similar result for that 24 hour period  of air freight. So can we then, the spike in temperature, of that 24 hour period, does make a difference. But only really at that really high core temperature management 16 degrees.
What was interesting though with fruit with storage disorders? The change in firmness over that four week period was much less. And as you can see, even at 16 degree air freight temperature, you only got down to about four kilos. When this occurs, that abnormal softening, I've called this, that the fruits has a problem and that there are storage disorders associated with that fruit. And here we have the flesh browning incidents from zero to a hundred percent. As you can see, after the first week of storage, at the importer, you started getting very severe flesh browning. But again, what's interesting just note, is that, there was, after two weeks at four degrees, the fruit that was air freighted at 16 degrees had much lower incidents of flesh browning, which gives us a clue to what we might want to do directly after harvest in terms of cooling and I will talk about that in a few weeks.
Now, with Flavour Pearl, we also did air freight simulation. Three temperatures for 24 hours of three different air freight temperatures. But in this case, there was very little difference in terms of loss over four weeks at four degrees, and the fruit ripens pretty much normally, and similarly, regardless of air freight temperature. And this is the actual physiological maturity measured with a DA meter and very little difference in maturity, physiological maturity over that storage period. So Flavour Pearl is an unusual variety. It's a very robust variety. The maturity drops during cool storage, but there's little change in firmness, but it does ripen very quickly, and similarly. And it wasn't very, there was very little impact of air freight temperature. Again, this highlights how important cultivar variety is in terms of storage performance. I think that's all I wanted to say there.
So that's how we run our commercial simulations. Now we're going to look at some shelf life model and then prediction.
So what we've been able to do is store fruits, different varieties, at seven different temperatures and see their behaviour over the different storage periods. And this is an example from Majestic Pearl. The low temperature storage, and then 8 degrees, 12, 16, and you can see the different behaviour and the short storage period as related to differences in temperature.
So we collect all this data and we're able to model actual commercial export scenarios. And I'm going to do that now. So what we have here is an Excel spreadsheet, with a model based on our experiments, our temperature and storage experiments behind the Excel spreadsheet. I'm not going to show you the model, but I'm not sure how you, what you can do with this model.  So here we have the harvest maturity, so you can modify this depending on the variety and in what harvest, what firmness and harvest maturity. The duration of each step in the export chains, so harvest to freight forwarders, sea or air freight duration, importer storage, distribution retail, and the consumer phase. You can vary the temperature of each of those phases / stages. And then you can get average firmness or the change in firmness as you move along the export chain. And this is the accumulation, I'm not gonna talk much about it, but this is the total degree hours, accumulated above zero as we move along the chain. So I'm going to double click on it and hopefully it works.
It won't because I got to go back. So I'm going to escape, double click. And here we go, zoom in. And so we can have a look and play around with it. So I'm going to run a sea freight scenario that is probably pretty common, and we've done it to assume a harvest firmness of seven kilos. So I'll put that in. So let's assume a standard air freight scenarios in terms of durations we know. So harvest to freight forwarder, we don't believe that you can get, a grower can get the fruits to the freight forwarder before, any earlier than four days. So let's just say, ideally, they managed to do it in four days. Then, I believe that the average sea freight period is about 25 days at this stage, but let's say 22, just for the sake of this example. Okay, so we've assumed three degrees, average temperature between harvest and freight forwarder. Two degrees, it is more likely to be one degree, but let's say two degrees during sea freight for 22 days.  And so at the end of sea freight, the firmness has dropped from seven to 5.7 kilos. And this is average firmness. Then let's say the importer would, once they store the fruit for five days and stores the fruit at five degrees, sorry, three degrees for 5 days. The fruit therefore dropped from 5.7 to 3.4 kilos.
Okay, so this is just demonstrating, and this is for Majestic Pearl, this particular scenario, and then we might say the retail, the distribution retail then takes two days and eight degrees Celsius. So the consumer by, after that time, fruit firmness is basically down to almost eating firmness of one to one and a half kilos. And then the consumer, leaves it on their bench at 18 degrees for let's say one day before consumption. Well it's eating firmness and beyond. So this little Excel calculator demonstrates the power of modelling shelf life and storage life. And so you can vary, we can run through another scenario very quickly.
We'll leave that at 4 degrees. Let's say air freight is more realistic. I, sorry, we can run an air freight scenario. Sorry. We've just done a sea freight. So lets say air freight - two days at 12 degrees. Okay. You might be surprised that there's very little change in firmness over that six days at those temperatures. Well don't be because that's what you tend to find. You don't see the effect of high temperatures until later on in the export chain, you won't to see it straight away. It's just to behaviour of our cultivars. That's how they'd behave. But then the importer storage, let's say six days and say 4 degrees. So after air freight, the importer stores it, stores the fruit for six days at four degrees and the fruit has dropped down to five kilos. Then the, let's say distribution might take three days and it might be 10 degrees, on average rather than eight.  See the impact there of that temperature's only seen at the end of the export chain where the fruit tends to soften rapidly, even at eight degrees, it's 1.9 and then the consumer obviously has maybe a day  or a bit to consume the fruit.
So I just want to demonstrate that to you, this kind of approach where, a grower, exporter, importer or retail, can you use this sort of calculator to determine how quickly fruit will soften, but then there is another way of looking at it. And this is what is more likely to be used by someone along the export chain, whether it's an exporter or importer or retailer. And to determine the remaining shelf life or storage period. So that previous calculator was just to play around with temperature and storage durations to understand how firmness changes with those parameters. This is actually useful in terms of predicting what is going to happen to your fruit based on what's already happened to it.
So I'm going to run again each one and use some examples. And hopefully this is interesting for you just to have a look how this can work, noting that the Queensland department is actually developing a mobile app for Mangos and Stone fruit, for industry, which incorporates some of these calculations into a very simple user interface.
This is just showing you in a bit more detail, but will not be the final product.  So say you're a, an importer and what you've got here is again, you've got harvest to freight forwarder, number of days, the temperature in each stage, and this tells you that the reminding storage period. Now as the importer, what you would need to know is what, how many days, if you want to estimate remaining days, the shelf life as an importer, while you actually need to know this information and you might obtain it from your exporter, just from temperature monitoring. And then once the fruit arrives, you could actually estimate shelf life and storage life. And you do that by inputting a desired firmness. At which point you'd want to, need to sell the fruit as an importer. So you might say, I can keep the fruit until it 4 kilos, and then I have to move it on to the retailer. So, the power of this is actually, you can select the minimum desired firmness as an important, for example.
So let's say five kilos. Right, so let's assume that five days at three degrees. So this is importer doing the calculation. Then you know that the fruit took 23 days to get to you at two degrees. You've got a problem. Your minimum firmness of five kilos has already been reached, right. So this is the issue. So let's change it to 21 days, right? You will receive that fruit at one kilo, so you've got , sorry, that's not kilos it's days remaining. So, under these conditions for this particular, this is majestic Pearl, at a harvest maturity of about six kilos, I think this model is based on, and you can vary that, but this is six kilo harvest maturity. If you want to, if you want to know how quickly you need to offload the fruit before it gets to five kilos, we've got one day remaining before you have to sell the fruit. But if you can hold the fruit until it's four kilos firmness, you've got five days at 3 degrees, and you can see that. If you've sorted for two degrees, you've got two to three days remaining.  So you can play around with storage time and storage temperature, and a minimum firmness to actually determine how much time you've got left before you have to get rid of the, or on-sell the fruit. And again, if you can hold the fruit until 3 kilos, then you'll find that you've actually got,  (and get rid of that) , when you receive the fruit, you've got nine days to play with before you have to sell the fruit. So it's quite a powerful calculator because you can play around with these different scenarios. If I increase that to 27 days and you can keep the fruit until it reaches 3 kilo firmness, you've got five days rather than nine. Again, demonstrating the power of it and you can do the same as a retailer. You do the side thing, except now that, now that you're a retailer, so you can hold the fruit until it drops down to two and a half kilos before it has to be sold. And if we do the same thing, five days, 21 days, and this is just telling you that the fruit still fine if you continue, the importer stored it for three days, you've got as a retailer, three days to sell the fruit before it gets too, it reaches this firmness. And that's a firmness that the consumer would want to purchase at and consume after a few days of buying it. So I just want to show you what's possible and ideally we will have a mobile app, a much simpler app where you can just put in some temperatures and storage periods and it gives you a warning about how many days are left of shelf life based on those temperatures and storage durations.
Okay. So I'm going to move on, and we're probably nearly there. I'm nearly done.
So to summarize temperature, duration and quality. A good temperature management during export is still critical though. I've tried to use some unusual results from higher temperatures compared to a lot of temperatures. But in the end of the day, good temperature management is critical. But temperature impacts on quality can depend on the variety and the storage durations. So you have to take those into account. and then we've also seen that, for example, short bursts of the warmer temperature during export, during the post harvest chain, could potentially be beneficial. And that's why we've looked at delayed cooling after harvest, which I'll talk about in a few weeks and you'll see that there are some benefits potentially not fast cooling or immediately cooling, fruit. Simulation trials that we've conducted have provided insights into storage potential of the different varieties we've looked at under realistic commercial / export conditions. But more monitoring, temperature monitoring is required during grower handling, cooling and packing as well as after air and sea freight during the import of storage and retail, because we really don't know what's going on at those stages in the export chain, with temperatures. And we've seen that the real impact on quality, due to temperature and storage time, can be understood using shelf life prediction.
So the next step for us is to develop these models further for different varieties. And we're looking at doing at least six varieties by the end of the project or producing models, six varieties. We were hoping to do commercial validation this season, but with the coronavirus and lockdown, we will probably have to do simulated validation in our own cool rooms rather, because we're unlikely to get overseas. And industry probably requires a simple to use real time eyeball app which has been developed. And just finally, I think this kind of work, especially with the sea freight is very relevant at the moment because it looks like it will be quite difficult to air freight a lot of our cultivars this season because of limited flights into our export markets. So we are going to have to sea freight a lot of these cultivars. And so knowing that storage potentials and whether they can actually make the journey and still ripen properly and be good, have good eating quality for the consumer is really important and timely.

For further information contact:
John Lopresti, Research Scientist, Agriculture Victoria
email: john.lopresti @agriculture.vic.gov.au

Acknowledgements

The calculator was developed by the Decision Aid Team as part of the Serviced Supply Chain project. The Serviced Supply Chains project is funded by the Hort Frontiers Asian markets Fund, part of the Hort Frontiers Asian strategic partnership initiative developed by Hort Innovation, with co-investment from Agriculture Victoria, the Department of Agriculture and Fisheries Queensland (DAFQ), Montague Fresh (summerfruit), Manbulloo (mangoes), Glen Grove (citrus), the Australian Government plus in-kind support from University of Queensland and the Chinese Academy of Sciences.