343 PROXIMATE COMPOSITION, ACCEPTABILITY AND STABILITY OF PROBIOTIC DAIRY YOGHURT CONTAINING COOKING BANANA/MATOOKE PUREE AND Lactobacillus rhamnosus yoba Ivan Muzira Mukisa 1  and Shamim Warugaba Birungi 2 Address(es): Dr. Ivan Muzira Mukisa, 1 Department of Food Technology and Nutrition, Makerere University, P.O. Box 7062, Kampala, Uganda, Tel: +256 775 414 537. 2 Department of Food Technology and Nutrition, Makerere University, P.O. Box 7062, Kampala, Uganda, Tel: +256 703 330 933. *Corresponding author: ivanmukisa@caes.mak.ac.ug; ivanmukisa@gmail.com ABSTRACT Keywords: Fruit yoghurt; cooking banana; matooke; Lactobacillus rhamnosus yoba; Probiotic INTRODUCTION Probiotics are ‘live microorganisms which when administered in adequate amounts confer a health benefit to the consumer’ (FAO/WHO, 2002). There is increasing global interest in the use of probiotics owing to the range of associated health benefits. Lactobacillus rhamnosus GG (LGG) is a widely studied probiotic that is beneficial in the treatment of gastrointestinal diseases (Guandalini, 2011; Horvath et al., 2011). LGG reduces the duration of rotavirus-associated diarrhea, a major health concern in children in Uganda and several developing countries (Guandalini, 2011; Nakawesi et al., 2010). However, access to affordable probiotics and acceptable food carriers are major challenges for adoption of probiotics in Africa (Franz et al., 2014). Generic forms of probiotics, such Lactobacillus rhamnosus yoba (a generic form of LGG), can be used to increase access to probiotics in Uganda and other developing countries (Kort and Sybesma, 2012). Locally consumed foods in Uganda, such as yoghurt and banana, can be evaluated as probiotic carriers for Lactobacillus rhamnosus yoba. Yoghurt is a product of the lactic fermentation of milk by starter cultures, resulting in a pH drop to ≤ 4.6 (Tamime, 2002). Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus are the major symbiotic starter cultures used (Codex Alimentarius, 2003). A mixed starter culture of Lactobacillus rhamnosus yoba and Streptococcus thermophilus C106 has also been used to ferment dairy yoghurt, Mutandabota (baobab pulp and milk), and cereal beverages such as Obushera, Uji and Zom Kom (Kort et al., 2015). Lactobacillus rhamnosus yoba is unable to degrade lactose and casein in milk while Streptococcus thermophilus C106 has the ability and thus inclusion of the latter facilitates growth of the probiotic in dairy products (Kort et al., 2015). Yogurt is among the most common dairy products consumed around the world (Saint-Eve et al., 2006) and is also commonly used as a probiotic carrier (Franz et al., 2014). In Uganda, yoghurt is popular amongst all social classes (Balikowa, 2011) and is thus a potentially acceptable carrier for probiotics targeting the Ugandan market. The Ugandan market has two types of yoghurt: set and stirred yoghurts, although the latter is more common (Mukisa and Kyoshabire, 2010). Most of the brands are flavored with synthetic flavorants while very few contain dried fruit pieces. The demand for fruity yoghurts with different flavours has been on the rise because fruits and fruit flavours significantly increase yoghurt consumption among all age groups (Chandan, 2011). Fruit preparations are commonly added to yoghurt formulations at levels of 10 – 15%, which should ideally cause minimal or no negative effects on the product’s aesthetic appeal (Chandan, 2014). The cooking banana/matooke (Musa spp. AAA-EA group) is extensively grown in Uganda (Karamura et al., 1998). It is highly perishable and is generally eaten in cooked form before ripening (Karamura et al., 1998). About 22 – 45% of matooke is lost during peak production seasons due to the rapid ripening, inadequate storage and transportation, and lack of alternative food processing options (Muranga et al., 2010). Raw matooke has been evaluated for use in bread making (Muranga et al., 2010) and in development of complementary foods (Muranga et al., 2009; Muranga et al., 2011). However, there are no known studies on the utilization of ripe matooke in any value addition processes such as production of fruit based dairy yoghurts. Lactobacillus rhamnosus yoba has previously been used to produce an acceptable fruit yoghurt-like product called Mutandabota¸ which contains 14% baobab fruit in milk (Mpofu, 2015). The objective of this study was to utilize ripened matooke in the production of probiotic dairy yoghurt containing Lactobacillus rhamnosus yoba. We evaluated the effect of banana concentration on growth of Lactobacillus rhamnosus and acceptability of the yoghurt. Proximate composition and shelf stability of the most acceptable banana yoghurt formulation were also determined. Using ripe matooke in fruit yoghurt production can reduce postharvest losses of matooke. The probiotic banana yoghurt developed can be targeted at children to help prevent or manage diarrhea. MATERIALS AND METHODS Milk, sugar and banana Pasteurized milk (Jesa Dairy Ltd, Uganda) and brown sugar (Kakira Sugar Ltd, Jinja Uganda) were purchased from Tusky’s supermarket, Makerere, Kampala. Fresh unripe matooke were purchased from the Kasubi market, Kampala and allowed to ripen at room temperature for five days. Cooking bananas/matooke are eaten in the unripe state but quickly ripen leading to postharvest losses. The purpose of this study was to develop fruit-based probiotic dairy yoghurt using ripe matooke and Lactobacillus rhamnosus yoba. Yoghurt mixtures containing varying proportions of matooke (0%, 5%, 7.5% and 10%) were fermented at room temperature for 32 hours. Acidity, pH and counts of Lactobacillus rhamnosus were determined during fermentation and storage (4°C for three weeks). Consumer acceptability was determined at weekly intervals. Lactobacillus rhamnosus counts increased from 7 – 9 log cfu.g -1 after 24 hours of fermentation. Banana accelerated the acidification rate with banana yoghurts attaining pH = 4.4 – 4.5 and acidity of 0.60 – 0.67% in 24 hours. The control took 32 hours to attain a pH = 4.5. Ripe cooking banana introduced a slight banana aroma but did not significantly (p > 0.05) affect consumer acceptability. Yoghurt containing 7.5% banana was most acceptable and contained: 148 kcal 100 g -1 , 76.81% moisture, 12.37% carbohydrates, 6.18% protein, 3.35% fat, 0.77% ash and 1.04% calcium. Yoghurt with 7.5% banana was stable at 4°C for 21 days and maintained viable counts above the target of log 6 cfu.g -1 . This study showed that an acceptable fruit based probiotic yoghurt can be produced by adding ripe banana to the yoghurt mix. ARTICLE INFO Received 20. 6. 2017 Revised 19. 10. 2017 Accepted 20. 11. 2017 Published 1. 2. 2018 Regular article doi: 10.15414/jmbfs.2018.7.4.343-347