**2. Materials and Methods**

#### *2.1. Study Participants*

The study was conducted using the Computer-Assisted Personal Interview (CAPI) method. A total of 1009 adult Polish inhabitants were randomly recruited (inclusion criteria: age ≥ 18 years; willing to provide informed consent to participate in the study; involved in food purchasing in the household—either own or cooperative purchasing), based on data from the National Identification Number database, which is the universal electronic system for population registration. The included participants were verified to be representatives of the general population of Poland. The characteristics of the study participants are provided in Table 1.


**Table 1.** The characteristics of the included participants of the study (*n* = 1009).

\* Missing data in category: educational background *n* = 18; per capita net income *n* = 424; town of residence *n* = 7; household size *n* = 60; PLN—Polish Zloty (Polish currency).

In order to verify the representativeness of the studied sample, the distribution was compared with the characteristics of the general Polish population, as described by Statistics Poland [29]. It was verified if the proportions of gender groups were adequate when compared with the general population of adults and the studied population was stated to be representative for gender (*p* = 0.3684, Chi Square Test). Afterwards, it was verified if the proportions of age groups were adequate when compared with the general population of adults and for this assessment, it was assumed that for the youngest and oldest age group (19–29 years and ≥70 years), the proportion should be reduced, as in previous studies [16], to obtain an adequate number of respondents participating in grocery shopping. The general population of adults with indicated age groups reduced to 50% was compared with the studied population and it was stated to be representative for age (*p* = 0.5222, Chi Square Test).

#### *2.2. Assessment of Consumers' Acceptance of Enhanced Animal-Derived Food Products and Novel Packaging*

The questionnaire used in the study was developed for assessing the consumers' perception of the quality determinants of animal-based food products, quality improvement methods, and acceptance of those methods. It included questions related to the discussed issue, as presented in a previous study [17] (Table 2).


**Table 2.** The questionnaire applied in the study.

For the question on the quality determinants of food products of animal origin (Question 1), the researchers interpreted the obtained responses by clustering them in common groups associated with the same area as follows: origin (indicated by respondents as: country of origin, farming, organic farm, etc.), production technology (indicated as: certified production, process of production, technology, etc.), manufacturer (indicated as: known company, trademark, producer, etc.), components and nutritional value (indicated as: vitamins, minerals, food additives, etc.), visual and sensory characteristics

(indicated as: appearance, flavor, taste, etc.), expiry date (indicated as: shelf life, fresh product, production data, etc.), and cost (indicated as: price). An additional cluster contained the answers of respondents who declared that they were not able to define the quality determinants of food products of animal origin.

Similarly, for the question about the quality improvement methods applied for the food products of animal origin (Question 3), the researchers interpreted the obtained responses by clustering them in common groups associated with the same area, which allowed analyzing of the quality improvement methods associated with product enhancement and application of novel packaging. In the cluster of methods associated with product enhancement were those responses associated with descriptions such as additives, technology of production, and so on. On the other hand, in the cluster of methods associated with the application of novel packaging were those responses associated with descriptions such as dedicated packaging, proper packaging, or specific packaging described. An additional cluster contained the respondents' answers that were not related to the methods applied by producers (e.g., storage, not consuming products that are past the expiration date).

The structure of the interview and the order of questions allowed extending of the analysis from the most general issue associated with concept definition (what does quality mean for respondents), to market situation (what actions do they observe that can improve the quality), and finally, to the subjectively perceived acceptance (do they accept the observed actions). Thus, the data obtained from the interview were analyzed to verify the following potential associations:


#### *2.3. Statistical Analysis*

The frequency of specific answers provided in the subgroups was compared using the Chi Square Test. The accepted level of significance was set at *p* ≤ 0.05. Statistical analysis was conducted using Statgraphics Plus for Windows 4.0 (Statistical Graphics Corporation, Rockville, MD, USA).

## **3. Results**
