Development of TTI labels using vegetable oil blends as indicators.
Time-temperature control is a critical issue in the cold supply chain. TTI (Time-Temperature Indicator) labels are a useful device that visually show the cold chain history of a product, from its production to the sale, registering both time and temperature fluctuations. A recent study conducted by a group of Indonesian researchers (Khairunnisa et al., 2018), investigated the potential use of nine different vegetable oil blends as indicators for TTI labels.
The indicators used for the test were made from canola oil (CA), soybean oil (SB), and olive oil (OV) that have blended with different amounts of palm oil (PO). The blends were added with red lake (0.25% m/v) for colouring the indicators. The diffusion kinetic of these indicators was determined by applying labels on a waterproof photopaper material stored at different temperatures (4, 18, 29, 37 and 40°C).
The results indicate that the viscosity of the indicators is influenced by the fatty acid profile of the blends and the storage temperature. Using an Arrhenius equation, models have been created in order to predict the the diffusion length of an indicator based on specific time and temperature values. In conclusion, the authors point out that the results obtained so far are very promising, but further study is still needed before using these indicators commercially, for example, to increase their stability at lower temperatures through the addition of fatty acids.
Development of an innovative colorimetric label for monitoring lean pork freshness
The aim of a recent study conducted by a group of international researchers (Chen et al., 2019) was to develop an easy-to-use food package label for pork shelf-life assessment. For the test, these labels were applied on meat samples packaged in polyethylene terephthalate trays, won on-package indicator labels kept at 5°C for 8 days. These indicators contained three groups of ph-sensitive dyes, i.e.: (i) bromocresol purple, (ii) bromothymol blue, and (iii) a mixture of bromothymol blue and methyl red.
The meat was then differentiated between fresh (on 0-3 days), medium fresh (on 4-5 days) and spoled lean pork (on 6-8 days), as a result of ph-value, total volatile basic nitrogen (TVB-N) contents, aerobic plate counts and sensory scores. The results of the analysis on the total color difference of the principal components show that the label containing a mixture of bromothymol blue and methyl red at 3:2 proportion (at an initial pH of 5.0) was able to accurately discriminate fresh (red), medium fresh (goldenrod), and spoiled (green) pork in cold storage.
The statistical models obtained by partial least squares, can be used to predict the TVB-N contents and aerobic plate counts of pork from the color of the label. In conclusion, the authors point out that the use of these particular indicators allows the freshness of packaged pork meat to be monitored directly with the naked eye.
References: Khairunnisa et al., IOP Conf. Series: Earth and Environmental Science (ICDALC 2018), 335, 20–21 September 2018, Bogor, Indonesia; H.-z. Chen et al., LWT – Food Science and Technology, 99, 2019, 43-49.