Fully biobased and biodegradable materials have attracted a growing interest in the food packaging sector as they can help to reduce the negative impact of fossil-based plastics on the environment. Moreover, the addition of functionalities to these materials by introducing active molecules has become an essential requirement to create modern packaging able to extend food’s shelf-life while informing the consumer about food quality and freshness. In this study, we present an innovative bioplastic formulation for food packaging based on poly(hydroxybutyrate-co-valerate) (PHBV) and tannins as multifunctional additives. As a proof of concept, PHBV/tannin films were prepared by solvent casting, increasing the tannin content from 1 to 10 per hundred of resin (phr). Formic acid was used to reach a homogeneous distribution of the hydrophilic tannins into hydrophobic PHBV, which is remarkably challenging by using other solvents. Thanks to their well-known properties, the effect of tannins on the antioxidant, UV protection, and gas barrier properties of PHBV was evaluated. Samples containing 5 phr bioadditive revealed the best combination of these properties, also maintaining good transparency. Differential scanning calorimetry (DSC) investigations revealed that films are suitable for application from the fridge to potentially high temperatures for food heating (up to 200 °C). Tensile tests have also shown that Young’s modulus (900–1030 MPa) and tensile strength (20 MPa) are comparable with those of the common polymers and biopolymers for packaging. Besides the improvement of the PHBV properties for extending food’s shelf-life, it was also observed that PHBV/tannin could colorimetrically detect ammonia vapors, thus making this material potentially applicable as a smart indicator for food spoilage (e.g., detection of fish degradation). The presented outcomes suggest that tannins can add multifunctional properties to a polymeric material, opening up a new strategy to obtain an attractive alternative to petroleum-based plastics for smart food packaging applications.

中文翻译：

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全生物基聚羟基脂肪酸酯/单宁薄膜作为智能食品包装应用的多功能材料

完全生物基和可生物降解的材料在食品包装行业引起了越来越多的兴趣，因为它们有助于减少化石基塑料对环境的负面影响。此外，通过引入活性分子为这些材料添加功能已成为创造现代包装的基本要求，该包装能够延长食品的保质期，同时告知消费者食品质量和新鲜度。在这项研究中，我们提出了一种用于食品包装的创新生物塑料配方，该配方基于聚（羟基丁酸酯-co-戊酸）（PHBV）和单宁酸作为多功能添加剂。作为概念证明，PHBV/单宁薄膜通过溶剂浇铸制备，单宁含量从每百份树脂 1 增加到 10 (phr)。甲酸用于将亲水性单宁均匀分布到疏水性 PHBV 中，这对于使用其他溶剂来说非常具有挑战性。由于其众所周知的特性，单宁酸对 PHBV 的抗氧化、紫外线防护和气体阻隔特性的影响得到了评估。含有 5 份生物添加剂的样品显示了这些特性的最佳组合，同时还保持了良好的透明度。差示扫描量热法 (DSC) 调查表明，薄膜适用于从冰箱到食品加热的潜在高温（高达 200 °C）。拉伸试验还表明，杨氏模量（900-1030 MPa）和拉伸强度（20 MPa）与用于包装的普通聚合物和生物聚合物相当。除了改善 PHBV 特性以延长食品的保质期外，还观察到 PHBV/单宁可以比色法检测氨蒸气，从而使该材料有可能用作食品腐败的智能指示剂（例如，检测鱼的降解）。所呈现的结果表明，单宁可以为聚合物材料增加多功能特性，开辟了一种新策略，以获得用于智能食品包装应用的石油基塑料的有吸引力的替代品。除了改善 PHBV 特性以延长食品的保质期外，还观察到 PHBV/单宁可以比色法检测氨蒸气，从而使该材料有可能用作食品腐败的智能指示剂（例如，检测鱼的降解）。所呈现的结果表明，单宁可以为聚合物材料增加多功能特性，开辟了一种新策略，以获得用于智能食品包装应用的石油基塑料的有吸引力的替代品。除了改善 PHBV 特性以延长食品的保质期外，还观察到 PHBV/单宁可以比色法检测氨蒸气，从而使该材料有可能用作食品腐败的智能指示剂（例如，检测鱼的降解）。所呈现的结果表明，单宁可以为聚合物材料增加多功能特性，开辟了一种新策略，以获得用于智能食品包装应用的石油基塑料的有吸引力的替代品。