Evaluation of the taste and smell of bottled nutritive drinks

Critical review of electronic nose and tongue instruments prospects in pharmaceutical analysis

Electronic nose (enose, EN) and electronic tongue (etongue, ET) have been designed to simulate human senses of smell and taste in the best possible way. The signals acquired from a sensor array, combined with suitable data analysis system, are the basis for holistic analysis of samples. The efficiency of these instruments, regarding classification, discrimination, detection, monitoring and analytics of samples in different types of matrices, is utilized in many fields of science and industry, offering numerous practical applications. Popularity of both types of devices significantly increased during the last decade, mainly due to improvement of their sensitivity and selectivity. The electronic senses have been employed in pharmaceutical sciences for, among others, formulation development and quality assurance. This paper contains a review of some particular applications of EN and ET based instruments in pharmaceutical industry. In addition, development prospects and a critical summary of the state of art in the field were also surveyed.

Taste of milk from inflamed breasts of breastfeeding mothers with mastitis evaluated using a taste sensor

BACKGROUND

The refusal of infants to suckle from a breast that is inflamed with mastitis suggests that the taste of the milk has changed. However, the taste of milk from a breast with mastitis has never been empirically determined. The present study compares the taste of milk from breastfeeding mothers with or without mastitis and identifies specific changes in the taste of milk from mothers with mastitis.

SUBJECTS AND METHODS

The intensity of four basic tastes (sourness, saltiness, bitterness, and umami) of breastmilk from 24 healthy mothers at 3-5 days and at 2-3, 4-5, and 8-10 weeks postpartum and from 14 mothers with mastitis was determined objectively using a taste sensor. The intensity of each basic taste and the concentrations of main taste substances in milk were compared between the inflamed breasts and the normal breasts of control mothers or the contralateral asymptomatic breast of mothers with unilateral mastitis.

RESULTS

The transition from colostrum to mature milk was accompanied by changes in the taste of the milk, such as decreased saltiness and umami and increased bitterness and sourness. Umami and saltiness increased in milk from inflamed breasts. Contents of sodium, glutamate, and guanosine monophosphate increased in milk from inflamed breasts.

CONCLUSIONS

Tastes that were specifically associated with inflamed breasts appeared to include an increase in umami and saltiness, which might have resulted from an increased content in factors associated with umami and sodium.

Evaluation of the odour of Aminoleban® EN, taste-masked with flavoured powders, by human and electronic noses

OBJECTIVES

Aminoleban® EN is a bitter total enteral nutrient product with an unpleasant odour. The purpose of this study was to evaluate the odour of Aminoleban® EN, taste-masked with various flavoured powders, by human testing and by using an electronic nose system (Alpha M.O.S.).

METHODS

Initially, the odour of Aminoleban® EN alone at various concentrations was evaluated. Secondly, the odour of Aminoleban® EN with the addition of various flavoured powders was evaluated; the evaluation included data on odour intensity, preference levels and evoked taste image.

KEY FINDINGS

With the human nose, a concentration of 0.43 g/100 ml seemed to be the taste threshold for Aminoleban® EN. In the electronic nose system, principal component analysis revealed that concentrations over 0.39 g/100 ml Aminoleban® EN could be distinguished from water. It was clear from both human testing and using the electronic nose system that the unpleasant odour of Aminoleban® EN could be masked by pineapple- and plum-flavoured powders, both of which contain not only sweet but also sour components.

CONCLUSIONS

The electronic nose system may be useful for detecting odours at or below the level detectable by the human olfactory system and for classifying the quality of different odours, thus reducing the amount of human testing required.

A prospective study to assess the palatability of analgesic medicines in children

AIM

This study examined children's opinions on the taste of three analgesic medicines: paracetamol, ibuprofen and codeine.

BACKGROUND

Many medicines for children are unpleasant and unacceptable. Research has shown that children's taste preferences differ to adults, in whom palatability is often tested. Little British research exists on children's opinions on the palatability of medicines. This study aimed to address this gap in knowledge.

DESIGN

Prospective observational study.

METHODS

Between May-September 2008, hospital inpatients aged 5-16 years rated the taste of required analgesics on a 100-mm visual analogue scale. This incorporated a 5-point facial hedonic scale. They were also asked their favourite flavour and colour for a medicine.

RESULTS

A total of 159 children took part. Eighty-five males (53·5%) and 74 females (46·5%). The median age was 8 years (Inter-quartile range 6-11). The taste of ibuprofen was significantly preferred to paracetamol or codeine. Significant differences were observed depending if the medicine rated was taken first or second (for example pre-medication with paracetamol and ibuprofen). Younger children (5-8 years) were more likely to choose the extremes of the scale when grading than older children were. Preferred flavours on questioning were strawberry 44% and banana 17%. Favourite colours were pink 25·8% and red 20·8%, with girls more likely to choose pink and boys blue.

CONCLUSION

Ibuprofen was the most palatable analgesic medicine tested. Children reported they preferred fruit flavours and colour was sex dependent. Nurses when administering two medicines together should consider giving the least palatable first, for example paracetamol before ibuprofen for pre-medication.

Taste sensing systems (electronic tongues) for pharmaceutical applications

Electronic tongues are sensor array systems able to detect single substances as well as complex mixtures by means of particular sensor membranes and electrochemical techniques. Two systems are already commercially available, the Insent taste sensing system and the αAstree electronic tongue. In addition, various laboratory prototype versions exist. Besides the successful use in food industry, the implementation for pharmaceutical purposes has strongly grown within the recent years. A reason for this is the increased interest of developing palatable formulations, especially for children. As taste assessment of drugs comes along with challenges due to possible toxicity and subjectivity of the taste assessors, electronic tongues could offer a safe and objective alternative. In order to provide guidance on the use of these systems, possible fields of interest are presented in this review, as for example, system qualification, quality control, formulation development, comparison between marketed drug products, and the validation of the methods used. Further, different approaches for solid and liquid dosage forms are summarized. But, also the difficulty to obtain absolute statements regarding taste was identified and the need of more validated data was discussed to offer guidance for the next years of research and application of electronic tongues for pharmaceutical applications.

Recent advances in electronic tongues

This minireview describes the main developments of electronic tongues (e-tongues) and taste sensors in recent years, with a summary of the principles of detection and materials used in the sensing units. E-tongues are sensor arrays capable of distinguishing very similar liquids employing the concept of global selectivity, where the difference in the electrical response of different materials serves as a fingerprint for the analysed sample. They have been widely used for the analysis of wines, fruit juices, coffee, milk and beverages, in addition to the detection of trace amounts of impurities or pollutants in waters. Among the various principles of detection, electrochemical measurements and impedance spectroscopy are the most prominent. With regard to the materials for the sensing units, in most cases use is made of ultrathin films produced in a layer-by-layer fashion to yield higher sensitivity with the advantage of control of the film molecular architecture. The concept of e-tongues has been extended to biosensing by using sensing units capable of molecular recognition, as in films with immobilized antigens or enzymes with specific recognition for clinical diagnosis. Because the identification of samples is basically a classification task, there has been a trend to use artificial intelligence and information visualization methods to enhance the performance of e-tongues.

Evaluation of antioxidant activity and electronic taste and aroma properties of antho-beers from purple wheat grain

Moderate consumption of beer is known to be beneficial for health. Thus, antioxidant, likely taste, and aroma properties of antho-beers made from purple wheat grain (antho-grain) were evaluated. The 2,2-diphenyl-1-picryhydrazyl free radical (DPPH*) scavenging activity, total phenolic content (TPC), oxygen radical absorbance capacity (ORAC), and phenolic acid compositions of antho-bran were also investigated. DPPH* scavenging activity at 60 min was 50.6-59.9% for control and antho-beer extracts, 15.0-54.1% for antho-bran extracts and hydrolysates. The TPC ranged from 410 to 609 mg/L, from 84 to 95 mg/L, and from 2473 to 7634 mg/kg for control (from barley malt) and antho-beer original samples, control and antho-beer extracts, and antho-bran extracts and hydrolysates, respectively. The corresponding ORAC values were 3050-4181 mg/L, 2961-3184 mg/L, and 74-213 g/kg, respectively. The major known phenolic acids comprised four types in control beer, five types in antho-beers, and seven types in antho-bran hydrolysates. Total anthocyanin content of antho-bran was up to 1160 mg/kg. Differences in likely taste and aroma were found between control and antho-beers by using electronic tongue and nose methods. Brewing materials had an effect on the antioxidant, likely taste, and aroma properties of beers; however, antho-grain may have potential as a novel brewing material.

Sensor arrays for liquid sensing--electronic tongue systems

Electronic tongue systems are multisensor devices dedicated to automatic analysis of complicated composition samples and to the recognition of their characteristic properties. Recently, the number of publications covering this topic has significantly increased. Many possible architectures of such devices were proposed: potentiometric, voltammetric, as well as approaches embracing mass- and optical-sensors. For the analysis of sensor array data, various pattern recognition systems were proposed. All of these topics are summarized in this review. Moreover, additional problems are considered: miniaturization of electronic tongues and hybrid systems for liquid sensing.