**1. Introduction**

Food processing is one of the strategic sectors where developing countries can use their natural base in agriculture to reach the next level of economic development [1]. Food processing in developing countries was, until one or two decades ago, dominated by multinational companies headquartered in advanced economies. However, economic liberalization increased the competitiveness of the structure of the food industry, thereby contributing to more rapid food product and process innovations [2]. In developing countries, population increase, rapid urbanization, rise of the middle class and changing food habits led to a gradual increase in demand for processed, nutritious and healthy food products This has in turn contributed to the rise of micro, small, and medium scale food processing enterprises (MSMSFPE) that process a diversity of healthy and nutritious food products as a sustainable way to reduce postharvest losses and food waste, extend shelf life of food, boost food security, and contribute to national employment and national

**Citation:** Owino, W.O.; Ambuko, J.L. Mango Fruit Processing: Options for Small-Scale Processors in Developing Countries. *Agriculture* **2021**, *11*, 1105. https://doi.org/10.3390/agriculture 11111105

Academic Editor: Massimiliano Renna

Received: 20 August 2021 Accepted: 21 October 2021 Published: 6 November 2021

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gross domestic product. The small-scale nature of these food processing enterprises and low level of bureaucracy enables them to rapidly make strategic decisions to respond to demand or change in the local market. These MSMSFPE are however plagued with a number of both upstream and downstream supply chain challenges such as; poor road network especially in rural areas which increase the cost of sourcing of raw materials or distribution of processed products; in a number of developing countries, the food processing sector is still informal thus contributing to inefficiencies in the food value chain that lead to high retail cost of processed products; duplicity and overlaps in laws and regulations governing the food processing sector; confinement of the market of processed food products in urban areas; high cost of food processing equipment; high cost of energy, credit and taxation. However, these enterprises hold potential to economic development in the developing countries if made more competitive, through increased government initiatives, interventions and conducive regulatory and taxation policies, adoption of novel food products and processing innovations, with more stringent quality and safety management systems. Only then will they be able to ward off the challenge of competitive imports from more advanced economies.

One of the most important fruits with a greater potential for food processing in some of the developing countries is the mango. Mango fruit is the second most traded tropical fruit globally and ranks seventh in terms of production [3]. Mango, "also referred to as the 'king of fruits'", is a major fruit of the tropics and subtropics. Although the fruit is mainly consumed in its fresh state, mango can be processed into many nutritious and shelf-stable products. Mango production postharvest losses in developing countries such as Kenya have been estimated to be as high as over 50%, especially during the main harvest season [4]. Other countries such as Rwanda, India, Benin, and Ghana reported mango postharvest losses in the range of 30–80% during harvesting, packing, and distribution in retail and wholesale markets [5]. Processing of mango fruit into diverse shelf-stable products makes the seasonal fruit conveniently available to consumers all year round. Some of the common processed products from mango fruit are derived from the pulp. Apart from the primary products from mango pulp, derivatives of mango pulp can be used to enrich or flavor secondary products such as yoghurt, ice cream, beverages, and soft drinks. Byproducts of mango processing such as the peel and kernel have been shown to be rich in bioactive compounds including carotenoids, polyphenols, and dietary fibers. The byproducts of mango processing can be used in food fortification and manufacture of feeds, thereby gaining greater value from the fruit while reducing wastage. Although mango is amenable to processing into all these products, smallholder farmers and processors in developing countries have not fully exploited this potential. Over the years, research and food product development have contributed substantially to a number of unique and diverse processed mango products with specific qualities and nutritional attributes that are in demand by a wide array of consumers. These mango products are derived from appropriate food processing and value-addition technologies that transform fresh mango into shelf-stable products with ideal organoleptic, nutritional, and other quality attributes. The status of processing technologies and products from mango has been reviewed in the recent past by DeeptiSalvi and Karwe [6], Evans et al. [7], and Siddiq et al. [8]. This review focuses on the current trends in processing and value addition of mango applicable to micro, small and medium food processing enterprises in developing countries.

The mango products of interest described in this mini review include the following as illustrated in Figure 1.

**Figure 1.** Processing of different products derived from mango. (Modified from [8,9]).

#### **2. Fresh-Cut Mango (FCM)**

FCM is among the minimally processed fruits and vegetables with increased market demand within ready-to-eat fresh fruit products [10,11]. In general, the factors that are fundamental to the quality of FCM include quality of intact mango, mango cultivar, preharvest agronomic practices, harvest maturity, postharvest handling procedures, interval between harvest and processing of the FCM, and the preparation methods, i.e., sharp cutting tools, size and surface area of the slices, washing and removal of surface moisture [12,13]. Nevertheless, peeling and cutting operations involved in processing FCM eliminate the protective pericarp and stimulate the physiological and biochemical activities that predispose the product to dehydration, accelerated tissue softening, and surface browning. Hence, there is a much higher rate of deterioration compared to intact fruit. As a consequence, even with preservation treatments to extend their shelf life, FCM have a consumption window of just a few days. To assure fresh-like quality and extend the shelf life of FCM, currently a combination of treatments and preservation methods are utilized. The dip pretreatments incorporate disinfectants, antimicrobials, antibrowning, and texture-maintaining preservatives [8,14].

The most common disinfectants with antimicrobial activity for FCM are sodium hypochlorite (NaOCl), and calcium hypochlorite (CaCl2O2). The recommended dose of chlorine ranges between 50 and 200 ppm, pH 6.0–7.5, with a contact time of 2–5 min [10,15]. Some other available alternative sanitizers that can be used for FCM and that are available in the market include aqueous chlorine dioxide (<3 mg L−<sup>1</sup> in water) and hydrogen peroxide (an effective sanitizer especially against *Salmonella* spp., *E. coli* O157:H7, *B. subtilis*, and other foodborne microbes at a dose of <0.3 mg L−1, (in vapor form, otherwise it can be phytotoxic). Other sanitizers include calcium solutions (calcium chloride, calcium carbonate and calcium citrate, calcium lactate, calcium phosphate, calcium propionate, and calcium gluconate at a dose of 0.5% to 3% for 1–5 min). In addition, organic acids (0.5–1% ascorbic combined with 1–2% citric acids) are useful alternatives to sulfites in preventing browning and discoloration of cut slices. Acetic acid (vinegar) at a dose of 4% is also an effective antimicrobial [10,16]. The combination of these dipping treatments with edible or polysaccharide-based coating such as chitosan or alginate has also been demonstrated to be useful in extending the shelf life of fresh-cut products [9,17,18].
