Hygiene Warning for Liquid Food Packaging: Paper-Plastic Composites Need Full Control from Raw Materials to Production

Industrial growth and higher living standards have brought more milk and beverages into households, while paper-plastic packaging has become a familiar part of daily life. As convenience grows, protecting human health has become a central issue in the hygiene requirements for liquid food packaging.

Dairy and beverage packaging currently falls into three broad categories: paper-plastic composite packaging; plastic film packaging, including three-layer and five-layer films; and plastic bottle packaging, commonly made of high-density polyethylene (HDPE) and polyester (PET). The discussion below centers on paper-plastic composite materials as a reference for the industry.

As society advances, food-safety and environmental awareness grows, and technology evolves, developed countries have introduced stricter rules, while China has also set new plans for sustainable social development. Relevant national standards already cover paper-plastic composite packaging materials, with hygiene requirements aligned to those for food packaging base paper and food-grade polyethylene.

For liquid packaging materials to satisfy hygiene requirements and reach advanced performance, the raw materials must first comply with the applicable hygiene standards. Paper-plastic composites for dairy packaging mainly involve four inputs: paperboard supplies strength and stiffness; polyethylene blocks liquid contents and microorganisms; aluminium foil blocks oxygen, light and odours; and ink reproduces the graphics requested by customers through printing. Food hygiene and safety place strict demands on raw materials to preserve taste, nutrition and freshness. The following sections focus on three key materials: paperboard, ink and polyethylene.

1. Base paper for packaging. Although paper does not directly contact liquid foods, its role as food packaging base paper still carries demanding hygiene and safety criteria. Domestic requirements are mainly based on the 1990 Measures for the Administration of Domestic Food Packaging Base Paper, under which the base paper must meet GB11680, the Hygiene Standard for Food Packaging Base Paper, covering items such as fluorescent agents, colouring agents and heavy metals. In Europe and the United States, certification against relevant FDA clauses is also required; this covers not only finished base paper properties such as microorganisms, contaminants and odour, but also certification of raw materials, processing equipment and the environment used to make the base paper, ensuring the process meets food packaging requirements. Milk packaging paper faces additional special requirements, including board strength and moisture control, and prevention of secondary invasion by bacteria or microorganisms.
2. Printing ink. Heavy metals and solvents in ink can migrate both inward and outward, creating a major safety risk if they enter the packaged contents. Most countries now encourage environmentally friendly inks, alcohol-soluble inks and water-based inks, with water-based inks increasingly promoted as a green option. Some traditional printers, however, still rely on solvent-based inks, particularly toluene or xylene as the solvent. China has not yet issued clear rules on this, and many production and processing companies lack proper management and supervision. In developed countries in Europe and the United States, benzene-based solvents are explicitly banned in food packaging; if toluene or xylene penetrates the skin and enters the body, it can endanger haematopoietic function and the nervous system. Requirements for inks, especially solvent-based inks, mainly concern the following areas.

The first is heavy metal content. China has no specific standard for heavy metals in ink; current testing mainly references the arsenic and lead limits set in GB11680-89, the hygiene standard for base paper for food packaging. The EU standards EN71-3:1993 and EN71-7:1997, together with the US ASTM F963-96a, set strict standards and regulations for heavy metal content in ink. Cadmium, lead, chromium and arsenic pose serious human health hazards; long-term exposure and continuous accumulation in the body can weaken immune function and cause retarded intellectual development in infants and young children.

The second is residual volatile organic compounds (VOC), mainly organic solvent residues from solvent-based inks left in packaging materials. For VOC testing, reference can be made to China's industry standard Gravure Composite Plastic Film Ink (QB/T2024-1994), which stipulates that the combined residue of eight solvents — toluene, xylene, ethyl acetate, acetone and others — must not exceed 30 mg/m2. Inks used for dairy packaging printing are mainly solvent-based and water-based. Water-based inks deserve particular emphasis: their solvent is water, they have no environmental impact and are beneficial to human health, and they should be the main development direction for liquid packaging.

However, because of their higher cost and the higher printability demands they place on printing, most companies still use solvent-based printing inks.

1. Polyethylene for packaging. China's Hygiene Standard for Polyethylene Resin for Food Packaging (GB9691-1998) sets corresponding requirements for other organic substances, heavy metals, dyes and other impurities in polyethylene.

Once raw materials are assured, production process control is equally critical. The outer packaging of raw materials must meet hygiene requirements, including transport, storage, warehouse conditions and standards for placing materials. Facilities suitable for food packaging material processing are also needed, along with control of workshop air-conditioning temperature and humidity, and management of air purification, pressure and airtightness to ensure a sound processing environment. These areas require relatively high investment and operating costs, and many domestic enterprises have not given them sufficient attention in plant construction and production.

Operator health requirements and correct food-processing practices are another important part of hygiene and safety. Packaging material quality control measures should also be established, with high-performance equipment provided to meet food packaging requirements and ensure sound operation. Foreign matter should be kept out as far as possible, while online quality monitoring, recording, sorting and rejection all matter greatly. Factories should obtain ISO9000 and ISO14000 certification and ensure the ISO systems operate effectively, so as to guarantee the hygiene and safety of product quality and effectively prevent substandard products from reaching the market.

In short, meeting the safety and hygiene requirements of liquid packaging depends on high-standard raw materials, a good processing site, good processing machinery and equipment, employees with food hygiene and safety awareness, and a sound production and processing process—all of which are needed to secure the hygiene and safety quality of packaging materials.

Therefore, amid fierce market competition, many enterprises have avoided corresponding hygiene and safety measures in order to lower production costs, pursuing their own interests at the possible cost of serious harm to the environment and public health. At the same time, the industry lacks sound hygiene and safety access requirements, supervision and control are insufficient, and safety and hygiene are overlooked. We should step up publicity, give consumers the right to know, and strengthen supervision to drive improvement in product hygiene quality.

——Source: China Packaging Network (pack.cn); original link: http://news.pack.cn/show-362286.html