Evaluation of the mulch films biodegradation in soil: a methodological review

Plastic mulch films are widely used in agriculture, but most are not biodegradable in soil. Biodegradable mulch films are blends of different polymers whose composition-ratios vary notably from one product to another. Their degradation rates vary greatly according to the physio-chemical characteristics of the product and according to the properties of the soil and its microbial activity. The objective of this review is to provide an overview of the methods used to estimate the biodegradation performances of biodegradable plastics in the soil. In line with this objective, 80 papers were selected and systematically analyzed to extract information on the characteristics of the soil used in the experiments, the type of polymer analyzed, and the methods used to estimate biodegradation in soil environment. Our systematic analysis showed that studies were carried out under both laboratory-controlled and open-field conditions, with different approaches involving visual analysis, mass loss measurements, spectroscopy, and CO2 measurements. A linear estimation of biodegradation performance for four of the most common biodegradable polymers (i.e., polybutylene succinate, polybutylene succinate-co-adipate, polylactic acid, and polybutylene adipate-co-terephthalate), either pure or blended, showed a very wide range of results that appear only partially comparable. Many of the analyzed papers did not report soil characteristics at all, despite soil being one of the most important factors in the biodegradation process. Although methodologies for estimating biodegradation are well developed, at least under laboratory-controlled conditions, there is a need for a shared methodology to make results comparable among different experiments. Within such a shared methodology, visual analysis or mass loss measurements, despite not being able to scientifically prove the biodegradation of polymers, should not be discarded a priori as they might be useful indicators especially for open field experiments. When using indirect biodegradation indicators such as visual analysis or mass loss, it is necessary to couple them with CO2 measurements or to use materials whose biodegradability in the soil environment has already been tested.

Preparation and Characterization of Polybutylene Succinate Reinforced with Pure Cellulose Nanofibril and Lignocellulose Nanofibril Using Two-Step Process

This study reports the preparation of a polybutylene succinate (PBS) film reinforced with pure cellulose nanofibril (PCNF) and lignocellulose nanofibril (LCNF) by a two-step process that consists of solvent dispersion and twin-screw extrusion. Compared to the conventional one-step process, this method offered improved mechanical properties. The addition of 5% CNF increased the tensile properties up to 18.8%. Further, the effect of the lignin content was also studied by using LCNF as a reinforcement. The LCNF was prepared with and without a deep eutectic solvent (DES) pretreatment to gain LCNF with a lignin content that varied between 5, 19, and 30%. The mechanical properties results show that a 5% addition of LCNF to the PBS matrix increased its tensile strength and elastic modulus. Further, the morphological and thermal properties of the composites were also studied in detail.

Efficacy of Biopolymer/Starch Based Antimicrobial Packaging for Chicken Breast Fillets

Food contamination leading to the spoilage and growth of undesirable bacteria, which can occur at any stage along the food chain, is a significant problem in the food industry. In the present work, biopolymer polybutylene succinate (PBS) and polybutylene succinate/tapioca starch (PBS/TPS) films incorporating Biomaster-silver (BM) and SANAFOR® (SAN) were prepared and tested as food packaging to improve the lifespan of fresh chicken breast fillets when kept in a chiller for seven days. The incorporation of BM and SAN into both films demonstrated antimicrobial activity and could prolong the storability of chicken breast fillets until day 7. However, PBS + SAN 2%, PBS/TPS + SAN 1%, and PBS/TPS + SAN 2% films showed the lowest microbial log growth. In quality assessment, incorporation of BM and SAN into both film types enhanced the quality of the chicken breast fillets. However, PBS + SAN 1% film showed the most notable enhancement of chicken breast fillet quality, as it minimized color variation, slowed pH increment, decreased weight loss, and decelerated the hardening process of the chicken breast fillets. Therefore, we suggest that the PBS + SAN and PBS/TPS + SAN films produced in this work have potential use as antimicrobial packaging in the future.