Why are most seasoning bottles packaged in glass bottles?

Most condiment bottles are packaged in glass. The key reason is that the properties of glass are highly compatible with the usage requirements and safety standards of condiments, while also balancing practicality and affordability. This analysis can be conducted from four perspectives: safety, chemical stability, physical properties,  cost, and environmental friendliness.

I. Core Advantages: Safety Prioritized, Meets Food Contact Requirements
Condiments (such as soy sauce, vinegar, oil, salt, and spices) require long-term contact with packaging and are consumed directly, making safety a top priority. Glass offers irreplaceable advantages in this regard:

No Harmful Substance Migration: Glass, primarily composed of silicon dioxide (SiO₂), has a stable chemical structure. At normal operating temperatures (such as room temperature, refrigeration, or brief heating), it does not migrate harmful substances into the contents, unlike plastic (which may release plasticizers and bisphenol A) or metal (which may be corroded by acidic condiments and release metal ions). This makes it particularly suitable for storing acidic condiments like vinegar and lemon juice, as well as fat-soluble substances like oils and sauces. Food-Grade Compliance: Food packaging regulations worldwide (such as China's GB 4806.5 and US FDA standards) classify glass as a "safety-grade packaging material." This eliminates the need for additional additives like stabilizers and antioxidants, thus preventing contamination risks at the source.

II.Key Feature: Strong Chemical Stability, Protecting Condiment Quality
The flavor and shelf life of condiments are easily affected by external factors (such as oxygen, light, and chemical corrosion). The stability of glass maximizes their quality:

Acid and Alkali Corrosion Resistance: Whether it's acidic vinegar, alkaline soy sauce, or salty sauces, glass will not chemically react with it, causing deterioration of the packaging or altering the flavor of the contents. (For example, long-term storage of vinegar in a plastic bottle may cause corrosion and develop an unpleasant odor, while metal bottles may rust due to acid corrosion.) Excellent barrier properties: Glass is a "complete barrier" material, completely isolating oxygen, moisture, and external contaminants. It prevents oxygen from entering and causing oxidation of condiments (e.g., rancidity of cooking oil and moldy soy sauce). It also prevents moisture from evaporating (e.g., clumping of powdered spices) or absorbing moisture (e.g., salt and sugar becoming damp). It also blocks odors (e.g., plastic bottles absorb the odors of other foods in the refrigerator, affecting the flavor of condiments).

III. Practical Value: Physical Properties Suitable for Everyday Use
Glass' physical properties are highly compatible with the frequent use and reusability of condiment bottles:
High and Low Temperature Resistance: Glass can withstand large temperature swings (such as pouring hot oil directly from the refrigerator, or briefly heating condiment sauce in the microwave) and is resistant to deformation and cracking (note that tempered glass is more impact-resistant, and ordinary glass should be protected from sudden changes in temperature). Plastic bottles soften and deform easily when exposed to high temperatures, while metal bottles can be hot due to heat conduction.
High Transparency for Easy Inspection: Most glass condiment bottles are transparent or translucent, allowing users to directly see the remaining amount (preventing sudden runs) and the condition of the contents (e.g., whether the soy sauce is cloudy or the spices are damp and clumping) without having to remove the bottle cap, enhancing ease of use.
Smooth Surface for Easy Cleaning: Glass has a non-porous surface, allowing oil and sauce residue to be easily rinsed off with water or detergent. It is also less susceptible to bacterial growth (as plastic surfaces easily harbor dirt and can retain odors over time), making it particularly suitable for condiment bottles that need to be refilled repeatedly, such as salt shakers and sugar shakers.

IV. Cost and Environmental Protection: Balancing Economic Efficiency and Sustainability
From production, use, and recycling, glass packaging offers advantages in terms of "full lifecycle costs" and aligns with current environmental trends:
Controllable Production Costs: Glass's raw materials (quartz sand, soda ash, and limestone) are widely available and inexpensive, and the production process (blowing and pressing technologies) is mature. Large-scale production costs are lower than those of materials like ceramic and stainless steel, making it suitable for packaging of mass-produced consumer goods.
High Recyclability: Glass is 100% recyclable and reusable, and the recycling process does not degrade its properties (unlike plastic, which loses strength after repeated recycling). This reduces environmental pollution and lowers raw material costs for businesses, aligning with the industry trend toward "green packaging."