Abstract

Objective: To compare the effects of different packaging materials and packaging methods on the long-term storage stability of handmade hard candy and to provide practical evidence for packaging selection and quality control.

Methods: Handmade hard candy produced from the same batch on 6 March 2020 was selected for the study. Samples were packed using six different methods: sealed glass jars; biaxially oriented polypropylene (BOPP) bags; BOPP bags containing food-grade desiccant; individually wrapped candy using BOPP film; individually wrapped candy placed inside a BOPP outer bag; and individually wrapped candy placed inside a BOPP outer bag containing food-grade desiccant. All samples were stored under the same conditions in the candy production area and were periodically assessed for crispness, softening, sensory quality and sticking.

Results: Candy packaged only in individual BOPP wrappers showed softening after approximately three months. Candy stored in conventional BOPP packaging progressively lost crispness and subsequently softened. The addition of food-grade desiccant significantly delayed this process. At 12 months, samples packed in glass jars and BOPP packaging containing desiccant still maintained acceptable sensory quality. At 15 months, all samples except those stored in sealed glass jars had softened. The glass-jar samples remained crisp at both 15 and 24 months. Although individual BOPP wrapping provided limited long-term moisture protection, it effectively prevented individual candies from sticking to one another.

Conclusion: The moisture-barrier properties of the packaging material, package sealing performance and moisture control within the package have a significant influence on the long-term stability of handmade hard candy. Under the conditions of this study, sealed glass jars provided the best long-term protection. Food-grade desiccant substantially delayed softening in BOPP packaging but did not provide the same long-term protection as a high-barrier sealed packaging system.

Keywords: handmade hard candy; BOPP packaging; storage stability; moisture protection; moisture absorption; storage

1. Objective

Handmade hard candy is a high-sugar, low-moisture product. However, prolonged exposure to environmental moisture can result in moisture absorption, loss of crispness, softening and, in some circumstances, candies sticking together.

The primary objective of this study was to investigate the effect of different packaging materials and packaging structures on the storage stability of handmade hard candy.

To allow differences in the moisture-protection performance of the packaging systems to become more readily observable, the samples were not stored under the “cool, dry place” conditions recommended on the product label. Instead, they were stored in a relatively warm area of the production facility under natural humidity without specific humidity control.

2. Materials and Methods

2.1 Samples and Study Personnel

All samples were taken from the same batch of handmade hard candy produced on 6 March 2020, thereby minimising differences associated with formulation, production process and initial product condition.

Study personnel: Edward Wang, Brenton Baddeley and Jarred Morris.

2.2 Packaging Materials and Study Groups

The following packaging methods were evaluated:

1. Glass jar with the lid tightly sealed;
2. BOPP outer bag;
3. BOPP outer bag containing food-grade desiccant;
4. Individual BOPP wrapping of each candy;
5. Individually BOPP-wrapped candies placed inside a BOPP outer bag;
6. Individually BOPP-wrapped candies placed inside a BOPP outer bag containing food-grade desiccant.

The glass jars were supplied by Plasdene. The BOPP outer bags were supplied by Viewpak and had a thickness of approximately 50 μm. The individual BOPP wrapping film was supplied by Fiston and had a thickness of approximately 30 μm.

2.3 Storage Conditions

All samples were stored in the candy production area on top of a cabinet approximately 2 metres above floor level, close to the gas-heated production area but without direct contact with the gas equipment, flames or other direct heat sources.

Gas heating equipment is used during candy production. As heat rises, the sample storage location was relatively warm during production. Temperatures at this location were generally above 25°C during daytime production and could exceed 30°C during summer production. During winter nights, temperatures could fall to approximately 12°C.

No specific humidity control or dehumidification was applied during the study. The samples were exposed to the naturally varying humidity of the production environment.

The study therefore represents a long-term comparative packaging stability study conducted under relatively adverse real-world production conditions, rather than a standardised accelerated stability study under controlled temperature and relative humidity.

3. Results

On 6 June 2020, after approximately three months of storage, candy packed only in individual BOPP wrappers showed noticeable softening and was considered unacceptable in sensory quality. This group was therefore removed from subsequent effective sensory assessment.

On 6 September 2020, after six months of storage, the remaining groups were generally still acceptable. However, further comparison showed that all groups other than the glass-jar samples had experienced some degree of reduction in crispness.

On 6 December 2020, after nine months, the glass-jar samples and BOPP-packaged samples containing food-grade desiccant still maintained good sensory characteristics. Other conventional BOPP-packaged samples had noticeably softened.

On 6 March 2021, after 12 months, the glass-jar samples and BOPP packages containing food-grade desiccant continued to maintain acceptable sensory quality. Other packaging groups had completely softened.

On 6 June 2021, after 15 months, all groups other than the sealed glass-jar group had softened. The glass-jar samples were the only samples that continued to maintain good crispness.

On 6 March 2022, after 24 months of storage, the glass-jar samples were assessed again and continued to maintain a crisp hard-candy texture.

The study also found that although individually BOPP-wrapped candies softened relatively early, the physical separation of each candy prevented the candies from sticking together into a mass.

3.1 Comparison of Storage Stability by Packaging Method

Packaging Method	3 Months	6 Months	9 Months	12 Months	15 Months	24 Months
Sealed glass jar	Normal, crisp	Normal, crisp	Normal, crisp	Normal, crisp	Crisp	Crisp
BOPP outer bag	Normal	Reduced crispness	Softened	Completely softened	Softened	—
BOPP outer bag + desiccant	Normal	Reduced crispness	Good sensory quality	Acceptable sensory quality	Softened	—
Individual BOPP wrapping	Softened / unacceptable	Removed from effective sensory assessment	—	—	Softened	—
Individual BOPP wrapping + BOPP outer bag	Normal	Reduced crispness	Softened	Completely softened	Softened	—
Individual BOPP wrapping + BOPP outer bag + desiccant	Normal	Reduced crispness	Good sensory quality	Acceptable sensory quality	Softened	—

Note: “Normal, crisp” indicates no noticeable deterioration in texture. “Reduced crispness” indicates that the candy retained hard-candy characteristics but had lost some crispness compared with its initial condition. “Softened” indicates a noticeable reduction in hardness and crisp texture. “Completely softened” indicates that the product no longer retained the normal texture expected of hard candy. “—” indicates that no corresponding assessment result was recorded.

4. Discussion

The results demonstrate a clear difference in the long-term storage stability of handmade hard candy between the packaging systems tested.

Conventional BOPP film packaging provided physical separation and containment but showed limited long-term protection against environmental moisture. With increasing storage time, the candies first showed a reduction in crispness and subsequently softened.

The addition of food-grade desiccant clearly delayed this deterioration. Conventional BOPP-packaged samples had already softened after nine months and were completely softened after 12 months, whereas BOPP packages containing desiccant continued to maintain acceptable sensory quality at 12 months. However, by 15 months these samples had also softened.

This indicates that food-grade desiccant can significantly extend the period during which hard candy retains acceptable texture by controlling moisture within the package, but it cannot fully substitute for a packaging system with superior moisture-barrier and sealing performance.

The sealed glass jar showed the best performance of all packaging systems evaluated. Despite being stored in a production environment that periodically exceeded 25°C and could exceed 30°C during summer production, the glass-jar samples remained crisp after 24 months.

Individual BOPP wrapping demonstrated a different benefit. Although the 30 μm individual BOPP film did not provide sufficient long-term moisture protection when used alone, it physically separated individual pieces of candy and therefore prevented softened candies from sticking to one another.

5. Conclusion

Under identical product, storage-location and environmental conditions, substantial differences were observed between the packaging methods.

Sealed glass jars provided the best long-term stability, with the candy remaining crisp after 24 months under the relatively adverse real-world production environment. The addition of food-grade desiccant to BOPP packaging substantially delayed moisture-related softening, although the samples eventually softened by 15 months. Conventional BOPP film packaging provided more limited long-term moisture protection. Individual BOPP wrapping did not maintain long-term crispness when used alone, but effectively prevented individual candies from sticking together.

These findings demonstrate that moisture-barrier performance, sealing integrity and control of moisture within the package are important factors in maintaining the quality of handmade hard candy during extended storage.

This study was designed primarily to compare the protective performance of different packaging systems and should not, by itself, be interpreted as a determination of product shelf life. Separate long-term stability studies under cool, dry storage conditions and cold-room storage conditions are currently ongoing, and their results will be evaluated separately.