In Figure 2 the analysed product categories are shown. Information was taken from the labels. Every product category represents one type of packaging. 58% of all samples were (spoonable) yogurt, 10% drink yogurt; 18% Skyr, fresh cheese, curd, yogurt surrogates (plant yogurt) and drinks (e.g., flavoured milk) and 14% dessert such as ‘Creme Brulee’, ‘Mango Passione’ dessert and similar. Drinks and desserts were included in this study when these products were packaged in packaging means that could be used also for yogurt. Some of the desserts were packaged in glass packagings, which allowed correlations with such kind of packagings.
Interestingly, only a small part of the analysed packagings were made of glass (= 13), despite its advantages. Glass packagings are perceived as more pleasant and sustainable by consumers [ 118 ]. Saint-Eve et al. found better aroma preservation of flavoured stirred yogurts in glass packaging, compared to PS- and PP-based packaging [ 119 ], explained by higher barrier in case of glass packagings. Restricted use of glass is probably influenced by higher weight, higher packaging price, higher logistic costs due to packaging weight and volume (often not stackable) and safety concerns (glass breakage) at production sites.
The most often found packaging means were cups. The reason is the established production method thermoforming (see Section 3.1.6 ) and existing and well-developed (aseptic) filling lines at manufacturers. It is worth to mention that the number of packagings in each category does not represent how much volume is sold on the market. Several packagings are positioned in niche markets with low selling quantities. Surprising was that cups made of deep drawn or pulled fibre material or coated fibre material were not found, even though such materials have been subject of intensive research [ 95 117 ]. Only one packaging was found (not depicted) that consisted of formed, coated and sealed paper. (However, it was not deep drawn or pulled fibre material.)
In Figure 3 the amount of packagings in each packaging mean classification are shown. The depicted packagings are all different. However, in shops the same packaging mean can be used for different flavours of yogurt.
In Figure 4 , the amount of single packaging units per bundle is shown. Most packagings were sold as single packaging (124), 17 in bundles of 4 smaller units and the rest in bundles up to 2, 6, 8 and 12 smaller units. Bundles often require a secondary packaging. Bundles are perceived differently by consumers compared to single packagings [ 83 ], which is relevant for marketing [ 120 ].
In Table 1 the filling weights in g product per unit primary packaging are shown. The filling weights are widely distributed between 50 g and 1000 g. Filling weights of 150 g occur most often, followed by 500 g and 200 g for single packagings. For buckets, only one filling weight (1000 g) was observed.
Cups, buckets, bottles and glass packagings always have a head space volume. Therefore, filling ratios are always below one. Considering the previous mentioned restrictions for the interpretation (plastic) bottles have the best filling ratio with a mean value of 0.95, followed by bricks with a measured mean value of 0.93. For cups and glass packagings the filling ratios vary most, which is attributed to the variations in the packaging design. Flat packagings have a worse filling ratio. Overall, the filling ratio was above 70 wt.-% or vol.-% in almost all cases. Therefore, most of the analysed packagings cannot be considered as deceptive packagings.
Low filling ratios of cups are associated to foamed products. At foamed products such as mousse and whipped cream the density is lower than 1 g/cm 3 .
Values for pouches and bricks underestimate the filling ratio. These packagings are flexible and buckle when filled with water to determine the rim full weight. Therefore, real filling ratios might have higher values there when filled with real products.
A packaging is considered as a ‘deceptive packaging’ (in German ’Mogelpackung’) when it contains more than 30 vol.-% of headspace [ 121 122 ]. In Figure 5 the filling ratio is shown. It is calculated from the product weight in the packaging and the rim full weight. For simplification, the density of the food was assumed as 1 g/cm
The dominating materials for cups ( Figure 6 ) were PP (60%), followed by PS (32%). PET and rPET represented around 4% each. Only one sample was made of coated fibre material. Four samples could not be assigned to a certain material. This finding is interesting, since PLA was hardly or not at all present on the market, even though it has been a subject of research and development for packaging for several decades [ 123 134 ]. A possible explanation is that the bioplastic PLA is not seen by consumers as more sustainable as conventional plastics. The willingness to pay more for packagings perceived by consumers as non-sustainable is restricted [ 135 ]. PLA can be assumed to be a more expensive polymer. Moreover, recycling of PLA is not established (yet), even though, current regulations require higher recycling rates.
The minor part of cups (
n
= 13) was produced by injection moulding. These were made of PP. The rest of the samples were produced by thermoforming (n
= 95). The fibre-based cup was made by lamination.Dominating closures were aluminium lids with 86 % (
n
= 94). Moreover, PET (n
= 6), rPET (n
= 2), PP (n
= 2) and cellulosic fibre materials (coated and sealed paper) were used (n
= 1). In four samples, the material was unclear. 137,138,139,144,145,146,147,PP- and PET-packagings are well recyclable if they are transparent and clear [ 136 140 ]. For PP-recyclates, a commercial market exists [ 141 ], as well as for rPET. For PS a solvent-based recycling process is relevant [ 136 142 ]. Post-consumer recyclates often contain odour active substances [ 143 148 ]. A source for unpleasant odours is the filled good. Such must be considered when foods with volatile aroma components are packaged that migrate into the plastic material.
In Figure 7 the decoration of the cups (excluding lids) is shown.
Slightly less than half of the packagings had decoration that can be removed by consumers (shrink sleeves made of plastic film, thickness 40 to 50 µm; paper/carton wrappings with a thickness of 250–540 µm and paper wrappings at bundles) or had no decoration. Such packagings are considered as more recycling friendly if consumers remove the shrink sleeve and wrappings and dispose them separately. No decoration was observed at packagings sold at street shops for direct eating. Printing inks from direct print are potentially problematic for recycling since it required additional efforts to remove them.
One reason for different decoration materials (paper and plastic) is that different packaging materials are perceived differently concerning its sustainability and these may influence the perceived taste and quality [ 149 ]. Furthermore, decoration is relevant because printed claims on the decoration can influence ‘perceived taste’ and the ‘amount consumers were willing to pay for the product’ [ 150 ]. Decoration and its design is therefore a part of the marketing strategy [ 151 152 ]. Wang et al. found for yogurt packagings, that ‘consumers presented the highest preference for yogurt packaging shape, followed by graphics, label text and packaging colour’ [ 153 ].
All analysed buckets (
n
= 5) were made of PP by injection moulding. The lids were also made of PP. Decoration were in-mould labels.All analysed pouches (
n
= 5) were multilayer films made of unknown plastic types. Possible production methods were film extrusion and lamination. Decorations were directly printed on the films. The closures were made of plastics either. In one case, the secondary packaging was made of cardboard.From the analysed bottles (
n
= 14), ten were made of PET via injection blow moulding. Two bottles were made of PS, one by injection moulding and one by extrusion blow moulding, two bottles were made of PE-HD by extrusion blow moulding. A total of 12 of the 14 bottles had a printed plastic shrink sleeve, one a paper label and one a plastic label. In case of bundles, a carton sleeve was used. The closures were made of PE-HD closures made by injection moulding (n
= 10), PE (n
= 1) and aluminium lids (n
= 3).Glass packagings (
n
= 13) were for multi-use (n
= 4) and single use (n
= 9). The closures were lids of metal (n
= 8) presumably coated metal sheets, aluminium (n
= 2) and plastic (n
= 3). Glass packagings had a printed paper label (n
= 7), a printed paper/carton wrapping (n
= 4), a printed wrapping for a bundle (n
= 1) or a printed plastic label (n
= 1).Bricks (
n
= 4) were made of directly printed beverage carton made by extrusion coating. The closures were made of PE-HD (n
= 4).The cardboard types of the paper/carton wrappings and folding boxes are based on 40% FSC MIX and have different compositions of primary and secondary fibres ( Figure 8 ). The other part is 37% secondary fibres and 24% primary fibres. In total, 54 cartons were considered.
154,155,156,157,158,159,160,161,162,163,164,165,For recycling, the appearance is an important aspect, as sorting works via various scanning systems using near infrared radiation (NIR) [ 94 166 ]. Apart from black, colouring is negligible in sorting, but it does influence the colour results of the recyclates and it reduces their value. The appearance of the analysed packaging (packaging body, not labels; Figure 9 ) is mainly white (66%) or transparent (27%). A few products are coloured (4%) or brown (3%).
170,The colour and transparency is also of relevance because light-induced quality changes can occur [ 167 168 ]. These are explained by oxidation and were observed also at other dairy products [ 169 171 ].
If you have any questions on 100g Plastic shrink sleeve labelling yogurt cup, Yogurt Packaging Containers, 100g IML Plastic yogurt cup packaging, 260g Plastic IML oval Yogurt cup. We will give the professional answers to your questions.