RestorativeDentistry 604 DentalUpdate November 2011 Suzanne M Blacker An In Vitro Investigation of the Initial pH and Titratable Acidity of a Selection of Fruit Smoothies Abstract: Four commercially-available fruit smoothie drinks were assessed for both initial/baseline pH and titratable acidity. A commercially-available smooth orange juice drink was used as a positive control. Baseline pH and titratable acidity were measured by titrating each fruit smoothie with 0.5 mL increments of 1M sodium hydroxide (NaOH), and measuring the pH following the addition of each increment, until pH 7 and pH 10 were reached. Each of the fruit smoothies investigated demonstrated a low baseline pH and had relatively high titratable acidity. Owing to both their low pH and high titratable acidity, it would be advisable to limit the consumption of such fruit smoothies to meal times. Clinical Relevance: Fruit smoothies, which are made from pure fruit blended with 100% fruit juice, are a relatively new addition to the soft drinks market. It is recommended that they be consumed through a straw, similar to the advice given for other acidic soft drinks. Dent Update 2011; 38: 604–609 It has been claimed that fruit smoothies ‘are set to be the high street success story for the UK soft drinks industry over the next few years’. 1 In the UK, consumption of shop-purchased fruit smoothies has risen dramatically, from 6 million litres in 2001 1 to 51 million litres in 2010, having peaked at 79 million litres in 2007 2 and in 2010 UK smoothie sales were worth £141 million. 2 The true level of smoothie consumption is not known, however, as these figures exclude consumption of homemade drinks, as well as those bought from cafés, coffee shops and juice bars. The increase in smoothie consumption has been in line with the UK Government’s ‘five-a-day’ campaign which encourages the public to consume at least five portions of fruit and vegetables every day. 3 Many individuals see the consumption of fruit smoothies as one means of achieving this target. One serving of fruit smoothie can be counted as up to two of the recommended ‘five-a-day’. 3 Despite this campaign, the majority of adults and children are still not achieving this daily target. In 2007, fruit in the form of pure fruit juice accounted for an 11.6% share of the ‘5-a-day’ consumption in children, an 8% increase on the previous year. 4 Of the Suzanne M Blacker BDS, PhD, MFDS, RCSEd, AHEA, MDSci, Clinical Lecturer/ Honorary Specialist Registrar in Restorative Dentistry, Level 9, Dundee Dental Hospital and School, Park Place, Dundee DD1 4SY, Stephen L Creanor, PhD, BDS, FHEA, Professor of Oral Sciences and Director of Undergraduate Dental Studies, Peninsula Dental School, Peninsula College of Medicine and Dentistry, The University of Plymouth, Room C407, Portland Square, Plymouth PL4 8AA and Siobhan Creanor, BSc(Hons), CStat, CSci, FHEA, Lecturer in Health Statistics, Centre for Health and Environmental Statistics, Room 301, ITTC Building, Tamar Science Park, Plymouth, Devon, PL6 8BX. 1180 million litres of fruit juice consumed in the UK in 2010, smoothie consumption accounted for around 5%. 2 Historically, fruit smoothies appear to have originated in Brazil from juicing fruit. 5 Smoothies first appeared in the UK in 1994 and have steadily increased their share of the soft drink market. 5 Legally, there is no definition of a fruit smoothie, but it is well accepted in the soft drinks industry that fruit smoothies are made only from pure fruit blended with 100% fruit juice, not from concentrate, and with no added ingredients, such as dairy, sugar, sweeteners or water. 5,6 There are many varieties of fruit smoothies which use different combinations of a range of fruits, which contain various combinations of organic fruit acids such as citric, malic, phosphoric, oxalic and tartaric acids. Because of the acidic contribution to their composition, fruit smoothies, therefore, may have the potential to cause dental erosion. Dental erosion is an increasingly common problem in dentistry which can Stephen L Creanor and Siobhan Creanor