*Apple and Apple Pomace Production in Poland and the World*

According to the statistics, apples took third place (after bananas and watermelons), in 2019, in the terms of the popularity of fresh fruits in the world [16]. In that specific year, about 87.24 million metric tons of apples were produced worldwide (Figure 2). Poland is one of the largest producers of apples in the world (next to China, the United States and Turkey). From 2010 to 2018, the annual production of apples in Poland ranged from 1.877 to 3.9 million tons [16,17]. It is estimated that about 50% of all apples produced in Poland are processed for the production of apple juice concentrate [18]. Literature data show that 25–30 wt.% of the fresh apple used in the production of juice is a fruit by-product (i.e., apple pomace), which is considered a post-industrial organic waste [19]. Based on these facts, it can be calculated that about 0.5 million tons of AP were generated in Poland in 2018. For comparison, a neighbouring country, Germany, produces half as much AP (0.25 million tons/year) [20]. The literature shows that the largest apple producer, China, generates more than one million tons of apple pomace annually [21]. Countries such as New Zealand, Spain and Brazil are characterised by small amounts of generated apple juice by-products (from about 20,000 to 13,750 tons per year) [20]. Global apple production has reached over 87 million tons/year, resulting in 3.915–4.698 million AP (in 2019). Taking into account the fact that the production of 1 litre of apple juice requires about 1.6 kg of apples, 0.40–0.48 kg of AP is produced depending on the apple variety and processing type [22].

**Figure 2.** Global-scale production of the most popular fruits in 2019 [16].

A report published by the Food and Agriculture Organization of the United Nations (FAO) indicates that approximately 33.3% (1.6 billion tons) of the food produced worldwide for human consumption is wasted each year [23]. High standards of product quality are required to attract consumers, and hence, the exclusion of the foods lower product quality is one of the major reasons. This problem particularly affects developed countries, including China, Japan, EU countries, Canada and the USA [24]. Such large losses pose a serious threat to the status of food security, the natural environment and the economy.

Fruits, including apples, that deviate from the imposed standards, for example in terms of size and visual elements (colour intensity, discolouration, skin elasticity, defects: bruises, rots) are often discarded by producers, consumers and retailers [25]. It is estimated that approximately 3.7 trillion apples end up in landfills each year [26]. Furthermore, such a waste of food and improper AP waste management causes huge losses of water, land, fertilizer, energy, labour and capital, which are economically unprofitable [24,27]. The amount of generated AP will increase each year due to the growing production of apples in orchards and the increased demand for processed products (juices, concentrates, jams and purees). To avoid the abovementioned problems, it is necessary to introduce economically viable pathways for waste apples and AP, so that they could be further processed into valuable products. Indeed, the cost-effectiveness of such pathways depends on the amount of waste generated/collected, the need for additional storage space and appropriate equipment (wet apple pomace require immediate processing due to high humidity) and related costs for transportation [28].

In this paper, we suggest a number of strategies to reuse the waste originating from apples. Indeed, fresh apples can also be treated as waste and used as renewable feedstocks in many industries, but this review focuses only on the use of AP produced by apple processing processes. In our opinion, AP should be reused according to the principles of the circular economy.
