1. History of wine transportation

The transportation of wine began when it started to be produced using different grape varieties in different wine-growing regions, because it was one of the main beverages to provide a source of calories with hedonistic connotations. In ancient times, wine was transported in amphorae (Estreicher, 2002). These were used for many centuries before the introduction of other containers, such as wooden barrels and then glass bottles, which were more practical for the transportation and storage of wine. Over the years, Roman manufacturers constantly improved the design of amphorae for wine storage, with the aim of transporting a higher number during shipments. A larger clay container called dolium was also widely used throughout the Roman Empire for bigger shipments (Estreicher, 2002). Problems were encountered when transporting wine in larger amphorae over long distances for instance, it was almost impossible to completely seal the amphorae, which resulted in the high oxygenation of their content; therefore, their transportation over land was not efficient. For these reasons, clay containers were eventually abandoned in favour of wooden barrels (Estreicher, 2002). In the late nineteenth and early twentieth century, most of the wine was stored and transported in barrels as bulk containers. After this period, a rapid decrease in the use of barrels was observed due to the high cost attributed to their maintenance and were gradually replaced by other packaging materials such as metal cans, bags-in-boxes, tetra Pak and kegs for wine transportation (Work, 2014). In addition, the use of thick glass bottles became very widespread in the twentieth century, particularly for champagne wine, because they can withstand high pressures. The heavy weight of glass bottles, and in turn wine crates, led to an increase in shipping costs, thus causing wine business operators to switch by shipping inexpensive wine in massive plastic bladders, also known as flexitank bags. The ability of flexitank bags to hold up to 24,000 liters helped to improve profit margins and the environment, and it increased the global wine trade (Accorsi et al., 2014). ISO-tanks containers and stainless-steel wine tanks are also widely used to transport wine on long journeys over land.

2. Temperature and wine stability

Because it comprises a combination of several organic and inorganic components, wine is a complex matrix. The way end-consumers perceive the interactions of these components is linked to the concept of quality, defined as the combination of those features and characteristics of a product that satisfy consumer' needs (Henry et al., 2006). Therefore, any significant change in the composition of wine is considered to alter the quality (Charters and Pettigrew, 2006). In fact, if wine is stored at temperatures above 25 °C for an extended period of time, quality will be irreversibly affected (Ough, 1992). Also, if a temperature over 40 ºC is reached even for a shorter time, visual and sensory changes will be perceived (Ough, 1985). The browning of red and white wines has often been related to the aging of the product (Ibern-Gómez et al., 2000; Serra-Cayuela et al., 2013), and it is also known for being an indicator of a detrimental temperature effect (Berg and Akiyoshi, 1956). The physical state of the bottled wine can also be altered by temperature changes (e.g., pushed corks, leaking of wine, deposits and damaged labels), which can result in the customer deciding not to purchase it (Lam et al., 2013). Consumers expect to find clarity or absence of turbidity in quality wines. Turbidity (or light scattering) in wine is due to the presence of particles in suspension that block light rays, thus diffusing some of the light in different directions and creating what is called the Tyndall effect (Xu et al., 2019). This makes the wine seem opaque to various degrees. Particles in suspension, either veiled or dispersed in the liquid, will not only ruin the presentation of a wine, but they may also alter the wine flavour. No official guidelines are available regarding the turbidity of wines; however, the turbidity of 12 marketed red wines was found to range from 5.6 to 190 NTU in a previous study (Mutanen et al., 2007). Many factors can cause turbidity depending on temperature, such as protein instability, tannin and tartrate precipitations and casse (the French word for breakage); for example, some pigmented matter in red wines is soluble at normal temperatures, but at low temperatures (0 °C) it can precipitate causing turbidity in the wine. Therefore, it is advisable to eliminate part of the wine colloids by centrifugation or filtration before bottling. In addition, slow and gradual cooling leads to the formation of large bitartrate crystals (Ribéreau-Gayon et al., 2000). Casse has the effect of altering the appearance of a wine due to a loss of homogeneity in the colour and a formation of turbidity. It occurs when a wine is exposed to light, leading to the oxidation of bivalent (Fe²⁺) to trivalent (Fe³⁺) iron, which is highly insoluble in the presence of phosphates (e.g., iron (III) phosphate). In particular, high temperature and light can reduce cupric ions (Cu²⁺) to cuprous ions (Cu⁺), which in the presence of SO₂ can form insoluble cupric sulfite, which is also responsible for instability and haze formation (Ribéreau-Gayon et al., 2000).

Undesirable temperatures can lead to a substantial change in the aroma profile of a wine, and thus a substantial deterioration in quality (Scrimgeour et al., 2015; De Esteban et al., 2019). This change can occur by oxidation or reduction, and the concentration of some volatile compounds can increase or decrease, such as methyl butanol, a compound associated with off-odours when present at a high concentration in a wine (De Lerma et al., 2012; Fariña et al., 2015). For example, the presence of amyl alcohols reinforces the in-mouth structure of the alcoholic beverage, but at temperatures above 26 °C they increase in concentration (Ough et al., 1966); an excess of these compounds (> 400 mg/L) is associated with a poor quality product and unpleasant odors (Rapp and Versini, 1995).

3. Effects of temperature and vibration during shipment

Several studies on wine transport have proven that temperature fluctuations are the most detrimental factor for wine quality during its shipment, because they can lead to irreversible changes in the chemical and sensory profiles of the product, as well as an acceleration in the aging process (Meyer, 2002; Robinson et al., 2010; Marquez et al., 2012; Lam et al., 2013; Du Toit and Piquet, 2014). Wine bottles have little protection from temperature variations during transport in containers, thus potentially affecting quality (Hartley, 2008). Temperature fluctuation can be prevented by transporting wine in either insulated or refrigerated containers; the latter are also known as reefers, and they allow humidity and temperature to be controlled. Both options add significant costs to a container shipment, which are reflected in the final price of the bottle; therefore, unfortunately, only a limited proportion of wine shipments use temperature-controlled or insulated containers. Getahun et al. (2017) showed the efficiency of airflow and heat transfer in reefers when shipping fruit products. They developed an airflow model packaging system to monitor the temperature and airflow inside the reefer during the shipment of apple fruits. Non-uniform airflow and highly heterogeneous cooling were observed in the packaging boxes due to the absence of a vent-hole in the bottom side of the package; it is therefore essential that airflow be taken into account in the design of packaging boxes for transporting goods inside reefers, and for winemakers, food business operators and exporters to know the temperature fluctuations that their goods are exposed to during shipments and the vulnerability of the product itself. Meyer (2002) performed a study on temperature variations during wine shipments and their effect on wine quality. Results showed that the quality of wines exposed at high temperature changed irreversibly. It is common for wines to be submitted to extreme temperatures of up to 44 °C (Butzke et al., 2012) - often with significant fluctuations - when they are transported. MacCawley (2014) also showed that wines being transported overseas can undergo high variations in temperature (from -10 °C to 67 °C) in a shipping container; this can include a steady increase in temperature affecting wines shipped from winter temperatures to equator temperatures and further on to summer temperatures. The most extreme shipping temperatures are experienced during the trans-shipment phase, since relay ports are often located close to the equator. While the wine is resting in the trans-shipment phase, it is generally unprotected and therefore subjected to extreme diurnal temperature fluctuations. Research carried out by Butzke et al. (2012) comprises one of the most comprehensive documentations of temperature monitoring during wine transport within the USA. They recorded 26 individual shipments, containing a total of 47 recording devices, which departed from winery warehouses in California for 13 different destinations within the USA. They measured ethyl carbamate in the wine, a carcinogenic compound (Schlatter and Lutz, 1990) produced from urea and ethanol, and showed that the reaction accelerated at high storage temperatures. They also showed that temperature could fluctuate by as much as 21 °C in one day, which significantly impacted wine quality due to the expansion and contraction in volume of the wine. Between 20 and 40 °C, wine can thermally expand by up to 0.8 % of its volume, or 0.3 mL for each degree Celsius in extreme cases, such as in wines with high residual sugar. The repeated expansion and contraction of a wine subjected to daily fluctuations can cause significant changes to it: air is expelled from the bottle as the wine warms, possibly to the point of cork movement, and then air is drawn into the bottle as the wine cools, especially if the cork is compromised; this phenomenon is known as the “pump effect”. This effect increases the risk of oxidation of the wine, as well as a change in vapour pressure and carbon dioxide solubility (MacCawley, 2014).

Jung et al. (2014) also monitored the effects of temperature, movements and vibrations on wines transported over longer distances within Europe (Portugal, France and Italy to Germany). Their results showed that transportation had an effect on the potential aging of wines, depending on the wine matrix. Movement and vibrations at high (40 °C) and varying temperatures during transport had negative effects on the quality of the wine, such as browning of the wine (especially visible in white wine) and sensory changes, with a reduction in the “fresh and fruity” notes in the transported wine samples compared to non-transported ones.

Several commercial wines have been studied under various shipping and storage conditions: storage at 20 °C and 40 °C, a daily cycle of between 20 °C and 40 °C, and travel in a car trunk in winter time (Robinson et al., 2010). The results showed that the wines stored at the higher temperature (40 °C) were found to be significantly different from those stored at the lower temperature (20 °C) in terms of aroma profile; specifically, tropical fruit and apple aromas were negatively correlated with rubber and diesel aromas according to the sensory analysis. For the wines stored at the higher temperature (40 °C), several modifications were observed: a higher concentration of norisoprenoids 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN), vitispirane 1 and 2 and p-cymene, and a reduction in esters and acetates, as well as an acceleration in the aging process. As a result, wines stored at 40 °C were characterised by diesel, oxidized and rubber aromas, while those at lower temperatures maintained their citrus, floral and tropical fruit aromas.

Du Toit and Piquet (2014) evaluated the effects of constant and simulated shipping temperatures on the sensory composition of Chenin Blanc and Sauvignon Blanc wines. Wine samples were stored at constant temperatures (-4 °C, 15 °C and 37 °C), as well as at varied temperatures over a period of 46 days. Wines exposed to elevated temperatures developed off-odours, such as over-aged, sulfur-like and a yellow colour, while those left at a cooler temperature of 15 °C retained tropical aromas. The effect of varying the temperatures did not lead to larger aroma differences in wines compared to those left at a constant lower temperature.

Stump (2017) monitored 71 commercial Swiss wines; three bottles of each wine were stored for seven days under different temperature conditions: (1) constant 15 ºC to reflect cellar storage conditions, (2) constant 40 ºC to reflect a hot environment, and (3) day/night temperature cycle (15 - 40 ºC alternating every 12 hours) to simulate transcontinental shipping conditions. A loss of the anthocyanin content was reported in all the red wines and those exposed to an extreme temperature (40 ºC) suffered the greatest loss, as well as a high visual increase in degree of turbidity.

Walther et al. (2018) also monitored the temperature of Chardonnay wines during bulk shipments from Australia to Germany, and they found that temperatures ranged from 4 to 47 °C inside the containers. A decrease in SO₂ content and an increase in the intensity of the yellowness of the wines exposed to higher temperatures was observed, as well as a decrease in some volatile compounds (ethyl decanoate, ethyl dodecanoate and phenylethyl acetate). In addition, an increase in diethyl malate, diethyl succinate, decanoic acid, and dodecanoic acid in wines transported on container ships was found, as compared to wines transported by air. The sensory analysis showed an increase in the honey attribute and a decrease in freshness when temperatures were above 25 °C.

Studies on temperature and humidity of wine during shipment conducted by Leinberger (2006) and Marquez et al. (2012) showed that temperature fluctuations are more prevalent during the transport of wine by land than by sea. The daily temperature cycles associated with transport by sea were negligible compared to land transport, which showed an extreme daily temperature of 57 °C.

The impacts of shipping conditions both at sea and at port on two dry, white wines of different vintages were investigated by Crandles (2016). The wine samples were subjected to three temperature programmes: control conditions (15 °C), linear increase (15 °C steadily increasing to 45 °C), and diurnal fluctuation (15 °C/40 °C) in both movement and non-movement conditions. The diurnal and linear programmes resulted in similar oxygen transfer in the bottles, which was different to that of the control. The results of the chemical analysis showed significant differences for tartaric acid, free sulfur dioxide, total sulfur dioxide and percent cork weight loss after eight months of storage between the different treatments (diurnal non-movement treatment compared to linear non-movement and control treatments, and diurnal movement and control treatments). It was possible to differentiate the varieties of the wines in the descriptive sensory analysis, but not to distinguish them according to experimental treatment after one month of storage.

Zhao et al. (2018) also evaluated the influence of excessive ambient temperature (40 °C for 14 days) and vibration (150 rpm for 15 days) on the sensory and chemical profiles of wine. Their results showed that the elevated temperature changed the organoleptic properties of the wine by significantly reducing the concentrations of volatile compounds, such as isoamyl acetate, ethyl butanoate, ethyl-2-methylbutanoate, ethyl hexanoate, ethyl octanoate, β-damascenone and linalool, which are all compounds responsible for the fruity and floral aroma notes in wine as shown by Peinado et al. (2004). The sensory analysis confirmed a decrease in fruity and floral aromas in wine samples subjected to high temperature. Conversely, no significant differences were found in the effect of vibration on the chemical and sensory profiles of the wines. Finally, Atkin and Cholette (2017) interviewed wine supply chain professionals and American wine producers in order to gain an insight into how they perceived temperature fluctuations during wine delivery. About 65 % of the interviewees estimated that 1 to 2 % of their wines suffered from excess temperature during transportation, and only 16 % of respondents thought that adequate temperatures were maintained during the journey to the retailer.

The conditions at which wine is subjected during shipment and storage can play an important role in the reduction of its quality due to temperature changes, bottle movement and associated oxygen uptake. Wines can suffer from several chemical, organoleptic and physical defects when exposed to poor shipping and storage conditions, including the development of notes associated with oxidation, reduction of fruity aromas, reduction of carbon dioxide, colour changes, cork ejection, leakage and even broken packaging (Meyer, 2002). The effect of vibration on commercial red wine during storage in bottles was evaluated by Chung et al. (2008): an increase in total acidity was observed in the wines subjected to high levels of vibration (20 cm/s²), and an accelerated decrease in organic acids, tannins and refractive index was observed in wines undergoing higher levels of vibration than at lower levels (1.0 or 5.0 or 10 cm/s²). Finally, wines undergoing higher levels of vibration had lower propanol and isoamyl alcohol content. This indicates that minimizing the movement of a wine assists in retaining higher levels of alcohol and overall wine aroma. Doyon et al. (2005) have shown that storage duration and temperature affect oxygen permeation more than mechanical movement does. Butzke et al. (2012) have shown that transportation can cause a bottle aging effect on wine of between 1 and 18 months more than that on wine stored at cellar temperatures. Some studies performed on beers (Paternoster et al., 2017), which evaluated the performance of different beer packaging when subjected to vibration and in terms of thermal insulation, showed that cardboard combined with plastic foil was the best beer packaging regarding vibration damping and thermal insulation during transportation. These findings may also be applicable to wine transportation. It was also shown that the combined effect of temperature and vibration on beer resulted in a rapid decrease in oxygen, as well as a significant increase in total aldehyde, such as 2-methylpropanal, 2-methylbutanal and furfural (Paternoster et al., 2019; Jaskula‐Goiris et al., 2019). Reich-Weiser et al. (2010) performed a comparative study on the total greenhouse gas (GHG) emitted during the transportation of wine by train and truck. The GHG emissions were found to be lower by train than by truck. Therefore, selecting GHG efficient modes of wine transport can contribute to reducing the global wine trade's GHG emissions.

A study on the effect of transportation temperature and vibration on the quality of a winery product was also performed by our research group. Boxes containing bottles of grappa (an Italian distillate, obtained from fermented or semi-fermented grape pomace) were shipped from Italy to Mexico; the temperature, relative humidity and shock/acceleration were measured using a data logger (Testo 184 G1, West Chester, U.S.). The same experiment was carried out on grappa bottles transported by truck within Italy, but in a different season, to compare the variability of temperature, humidity and shock between transport by land and sea. A maximum temperature of 27 °C and a minimum of 17 °C (in April) were recorded outside of the grappa bottles (i.e., inside the cardboard boxes) for land transportation (Figure 1A). Maximum humidity was 67 % and minimum humidity 36 %, and a maximum shock of 28 g was observed (g, Gal or Galileo is the unit of acceleration used in gravimetry and is defined as 1 cm/s²). Regarding the overseas transport (Figure 1B), a maximum temperature of 25 °C and a minimum of 10 °C were recorded (in December). Relative humidity ranged from 31 to 70 %, whereas the mechanical shock ranged from 4 to 11 g. Land transportation thus generated a high number of shocks between the bottles. These preliminary results confirm the studies carried out by Leinberger (2006) and Marquez et al. (2012), who stated that temperature fluctuations during wine transport are more prevalent in land transport than sea transport.

Figure 1. Transportation of grappa samples. A: transport within Italy by truck (in April); B: transport from Italy to Mexico by sea (in December).

Save View full size Expand inline Collapse inline

A summary of all the published studies on the effect of transportation conditions on the quality of wine is presented in Table 1.

5. Devices for temperature monitoring

Stump (2017) monitored the ambient temperature and humidity of wine samples using data loggers (HAX0-8, LogTag Recorders Limited, Auckland, New Zealand) every 30 minutes over a three-week period, after which the logged information was downloaded. Meanwhile, Robinson et al. (2010) monitored temperature (with TG-3080, Omni Instruments, Arroyo Grande, CA) every 10 minutes over a three-week period, after which the logged information was collected. Jung et al. (2014) used a data logger (EL-USB-2, Lascar Electronics) to monitor the temperature of wines shipped from Germany to Japan, determine fluctuations during shipment and then to simulate those temperatures in their work on the evolution of wines during shipment. Butzke et al. (2012) used Dickson SP100 dual-channel data loggers (Dickson, Addison, IL) to monitor the temperature of wines every 15 minutes during commercial shipments. Finally, Biccario et al. (2014) proposed the Wireless Sensor Network (WSN) system as an effective solution to monitor the temperature, humidity and light exposition of food products during transportation.