Abstract:Population aging has become a universal phenomenon with the rapid development of the global economy and medical technology. China, which has the largest number of older adult people, has one of the highest aging rates in the world. Despite the large elderly population, the market lacks food designed to meet their safety and nutritional needs. Therefore, food development for older adults has become a popular research topic. In 2018, the National Health Commission of China released the “National Food Safety Standard–General Rules for Elderly Food” (draft for soliciting opinions), aiming to regulate food production and quality standards for older adults. It classifies food for older adults into easily consumable, nutritional-formula, and nutritional-supplement foods and sets specific nutritional requirements for them. Experts have proposed principles for developing food for older adults, including providing sufficient high-quality protein, dietary fiber, vitamins, and trace elements, while emphasizing low-fat, low-sugar, low-calorie, and low-cholesterol formula designs. Additionally, texture, sensory properties, and packaging suitability during food processing are considered to meet the physiological and psychological needs of older adults. Compared with the international market, the food market for older individuals in China is still in its infancy and sells mainly health products. The variety of foods suitable for older adults is relatively limited and includes milk powder, pastries, and biscuits. Although these foods are easy to chew and swallow, they often lack sufficient nutritional value and do not fully meet the nutritional needs of the elderly population. Research has shown that vitamin and folic acid content in domestic pre-packaged food for older individuals is insufficient, and the carbohydrate and energy content is often high, increasing the risk of obesity and cardiovascular and cerebrovascular diseases in older individuals with a low metabolic rate. Leveraging the high economic and nutritional value, as well as the delicious taste of seabass (Lateolabrax japonicus), its meat serves as an excellent source of high-quality protein with a low fat content, soft texture, and easy chewability, making it an ideal ingredient in food designed for older adults. Based on the dietary needs of older adults, this study developed an easily chewable and digestible seabass paste by adding carrot powder, celery powder, and inulin. Single-factor experiments and response surface methodology were used to determine the optimal ratios of the three nutrient powders, using hardness and sensory scores as key evaluation criteria. Textural characteristics and nutritional indicators of the products were also analyzed. The study also assessed the effect of different packaging methods (regular packaging and vacuum packaging) and refrigeration temperatures (4 ℃ and –2 ℃) on the quality of the sea bass product. Quality indicators included textural characteristics, sensory aspects, volatile basic nitrogen content (TVB-N), thiobarbituric acid value (TBA), and total colony count. The optimal amounts of nutrients for sea bass paste were 1.15% carrot powder, 1.10% celery powder, and 1.00% inulin. The paste contained 15.24 g protein and 5.73 g fat per 100 g. The amino acid profile aligned with the ideal protein pattern recommended by the Food and Agriculture Organization/World Health Organization. Moreover, the sea bass paste contained 18 types of fatty acids, with the relative unsaturated fatty acid content reaching 72.1% and the total EPA and DHA content accounting for 11.12%. The sea bass paste contained the highest amount of vitamin E (3.54 mg/100 g), followed by niacin (3.48 mg/100 g). It exhibits moderate texture, good water retention, and is easily chewable, making it suitable for consumption by older adults. During the first 20 days of storage, the hardness of sea bass paste gradually increased, but there was no significant difference between the two refrigeration temperature groups (4 and –2 ℃). However, the hardness of the vacuum-packed sea bass products continued to increase for up to 30 days of storage, but it decreased sharply in the regularly packaged product. Storage experiments demonstrated that vacuum packaging could effectively delay the increase in the TVB-N, TBA value, and total colony count, maintaining the quality of the sea bass paste. The TVB-N of the regularly packaged product was close to the 30 mg/100 g limit after 30 days, whereas vacuum-packed sea bass paste stored at –2 °C was still below 13 mg/100 g (within the range of Class Ⅰ products). Fat oxidation was higher in the regularly packaged fish paste than in the vacuum-packed group. This indicates that vacuum packing was effective in slowing down the fat-oxidation process. Vacuum-packed sea bass paste can be stored for 7 days at 4 ℃ and 15 days at –2 ℃, showing a significantly superior preservation effect compared to regular packaging. In conclusion, this study not only introduces a nutritious and healthy food option for older adults but also presents novel insights into the processing and high-value utilization of sea bass, offering technical support and a reference for the diversification and development of marine fish products.
