In the South African citrus fruit industry, maintaining the cold chain is vital to prolong the shelf life of citrus fruit and comply with phytosanitary temperature protocols for fruit-exporting countries.
Product visibility is a challenge for many fruit cold chains, and most challenges arise because of technological constraints, which lead to the inability to predict whether fruit temperatures are still within the stipulated requirements. Technologies such as temperature data loggers are used to record and communicate temperature measurements to ensure that the intricately linked cold chain for citrus fruit is well coordinated and offers the visibility of fruit temperature.
This article will delve into the use of strip charts, a type of temperature recorder, within the South African cold chain, particularly for citrus fruit exports.
Understanding Strip Charts
A normal road map typically provides a visual representation of roads, cities, landmarks, and geographical features on a two-dimensional surface. In contrast, a strip chart is a linear representation of distances between specific locations, often showing distances along a single route or road. Strip-chart monitors are temperature recorders that generate a permanent strip-chart record of temperature data and conditions along the supply chain.
Currently, strip charts can record information in digital format to be downloaded through a computer known as a virtual chart recorder.
Read also: Property Practitioners Regulatory Authority
Strip charts are typically operated at an accuracy of ±1.1 °C (±2.0 °F) and can measure temperature ranging from −29 °C to 38 °C [16].
Nico Vosloo explained that “the main temperature-monitoring instruments are wired loggers and wireless loggers, such as button loggers and strip charts” (personal communication, March 26, 2021).
Example of a strip chart recorder.
The Role of Temperature Loggers in the Citrus Cold Chain
The primary aim of temperature loggers is to establish the temperature history of citrus fruit across the different stages in the cold chain. The temperature history of citrus fruit is used for two primary reasons: first, importing countries can find out whether the fruit was exposed to the required temperature as stipulated in predefined protocols. This is an essential management control point.
Read also: Discover Thula Thula
Second, the temperature history can evaluate whether the fruit was stored appropriately to preserve quality during transit.
Ensuring that the cold chain of perishable products is maintained also requires purpose-designed packaging and an adequately designed cooling system with temperature-monitoring devices to measure changes in fruit pulp temperature and ambient temperature.
It is important to note that pulp temperature is used to determine the cooling rates and the success of cold-sterilisation treatment.
Significant logistical challenges exist in the South African citrus cold chain because export protocols require different temperature regimes. The Republic of China, for example, requires citrus to be shipped at −0.6 °C for 24 days, whereas citrus fruit exported to Japan requires temperature treatment of −0.6 °C for 12 days.
Significant temperature variation can lead to economic losses because of poor quality and failure to start phytosanitary protocols, resulting in penalties that increase the cost to exporters.
Read also: Traditional South African Bread
South African citrus fruit, ready for export.
Conventional Temperature Loggers
Conventional temperature loggers are predominantly used to monitor temperature during the different stages in the citrus cold chain. Most of the conventional loggers currently in use measure ambient temperature, but a few measure pulp temperature.
In this article, wired conventional loggers refer to temperature loggers that require the use of a cable or USB port to download temperature data.
Besides strip charts, other conventional temperature loggers include:
- Button Loggers
- USB Loggers
- USDA Probes
Limitations of Conventional Loggers
Concerns arise because temperature-monitoring loggers are not automated and therefore do not offer real-time temperature visibility. They require manual handling, which makes continuous access to temperature data impossible.
This has led to the exploration of cellular technologies to monitor the temperature of citrus fruit.
Cellular Loggers: An Alternative
Cellular technologies have been introduced in the cold chain to monitor the temperature of citrus fruit. Because it is difficult to get temperature data from conventional loggers, the remote monitoring provided by cellular technologies could prove beneficial to exporters wanting to monitor the temperature of their cargo while it is in transit.
Cellular loggers offer more real-time data than conventional loggers, but as they depend on cell-phone towers, they offer restricted real-time visibility, especially during the sea leg of the consignment.
Flow diagram illustrating the cold chain for citrus fruit from South Africa to cold protocol markets.
Temperature monitoring of fruit cold chain
Comparison of Logger Types
Below is a table summarizing the key differences between conventional and cellular loggers:
| Feature | Conventional Loggers | Cellular Loggers |
|---|---|---|
| Real-time Data | No | Yes, but with restrictions |
| Automation | Manual handling required | Automated data transmission |
| Cost | Low-cost option | Higher cost |
| Visibility | Limited | Improved, but dependent on cell coverage |
Popular articles:
tags: #Africa
