Fruits and fruit products are an essential part of the human diet. Their health benefits are directly related to their content of valuable bioactive compounds, such as polyphenols, anthocyanins, or ...vitamins. Heat treatments allow the production of stable and safe products; however, their sensory quality and chemical composition are subject to significant negative changes. The use of emerging non-thermal technologies, such as HPP (High Pressure Processing), has the potential to inactivate the microbial load while exerting minimal effects on the nutritional and organoleptic properties of food products. HPP is an adequate alternative to heat treatments and simultaneously achieves the purposes of preservation and maintenance of freshness characteristics and health benefits of the final products. However, compounds responsible for antioxidant activity can be significantly affected during treatment and storage of HPP-processed products. Therefore, this article reviews the effect of HPP treatment and subsequent storage on the antioxidant activity (oxygen radical absorbance capacity (ORAC) assay), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity assay, ferric reducing antioxidant power (FRAP) assay, 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging capacity assay or Trolox equivalent antioxidant capacity (TEAC) assay), and on the total phenolic, flavonoid, carotenoid, anthocyanin and vitamin contents of fruits and different processed fruit-based products.
The purpose of this study is to review the effects of High Hydrostatic Pressure Processing (HPP) on the safety of different fruit derivatives (juices, nectars, jams, purees, pastes…), considering the ...types established in the European legislation and some other vegetable-based beverages (mainly juices and smoothies). The main inactivation processes and mechanisms on microorganisms are reviewed. Studies have revealed that HPP treatment is capable of destroying most microorganisms, depending on the application conditions (amplitude of the pressure, duration time, temperature, and the mode of application), the properties of the fresh and processed fruit/vegetables (pH, nutrient composition, water activity, maturity stage), and the type of microorganisms or viruses.
Adulteration of foods is a serious economic problem concerning most food commodities, in particular fruit products. Since high-priced fruits command premium prices, producers of fruit-based products ...such as juices, jams, jellies, purées, and fruit preparations might be tempted to blend these products with cheaper fruits. In addition to admixtures of adulterants, the labelled fruit contents may not be met. Both types of adulteration are difficult to detect and lead to a deterioration of product quality. For consumer protection and to avoid unfair competition, it is of essential importance to guarantee both authenticity and compliance with the product specification. While approaches for the detection of fraudulent admixtures to fruit juices have extensively been reviewed, the objective of the present treatise is to provide an overview of the approaches so far suggested to detect and even quantify adulterations of the above-mentioned fruit products.
Resumo Em vista da crescente demanda da população por questões relacionadas à saúde, nutrição e bem-estar, o mercado alimentício tem se preocupado em aumentar a inserção de ingredientes mais ...saudáveis como as frutas, por exemplo, visando atender à nova demanda do consumidor. A otimização de um processo é dependente da presença de dados precisos que permitam o dimensionamento correto dos equipamentos. O objetivo deste trabalho foi caracterizar amostras comerciais de produtos à base de frutas e avaliar as propriedades termofísicas (densidade, calor específico, difusividade térmica e condutividade térmica) e reológicas (viscosidade aparente e energia de ativação), visando à adequação a modelos teóricos. Os resultados foram ajustados a modelos matemáticos apresentando erros relativos entre 0,2% e 50%, sendo o modelo de ajuste da densidade o mais preciso (erro máximo de 1,7%). O comportamento reológico das amostras teve melhor ajuste ao modelo Lei da Potência (R2 > 0,96) e a viscosidade relacionou-se bem com a temperatura, segundo a equação de Arrhenius (R2 > 0,90).
The aim of this study was to describe the structure of fruit preparations taken as models of polysaccharide-starch composite gels, according to the composition and the preparation procedure. For that ...purpose, model matrices have been prepared, the gelling agent being either pectin or carrageenan in combination with cross-linked waxy corn starch. The microstructure of these composite gels was studied by rheology and confocal laser scanning microscopy (CLSM) at different steps of the preparation procedure. The viscoelastic behaviour of these mixed systems clearly revealed the contribution of close-packed swollen starch granules in the dispersed phase and of the gelled network arising from the polysaccharide, located in the continuous phase. By CLSM, a heterogeneous microstructure with swollen starch granules unevenly distributed in the medium was shown. Pectin or carrageenan was mainly found in the continuous phase forming gelled fragments; part of the polysaccharide lay inside starch granules. These structural features are shown to be the direct consequence of the stirring applied during the cooling step of the preparation procedure while gelling of the polysaccharide took place. The resulting composite system was therefore more heterogeneous than expected.
The microbiological safety of commercial fruit processes was evaluated using α-amylase time–temperature integrators (TTI) from either a
Bacillus amyloliquefaciens or
Bacillus licheniformis source. ...The TTIs were incorporated into silicone particles that were added to batches of fruit preparations to estimate the pasteurisation achieved during two different methods of continuous processing: a tubular heat exchanger and an ohmic column. Pasteurisation values (
P-values) estimated with the TTIs represented the integrated thermal process at the core of 12-mm pear cubes for the tubular process of 12-mm strawberries, 12-mm pineapple and 10-mm blackcurrants for the ohmic process. The decimal reduction time at 85.0 °C (
D
85) for the
Bacillus amyloliquefaciens amylase was 6.8 min, with a kinetic factor (
z-value) of 9.4±0.3 °C, and for the
Bacillus licheniformis amylase the
D
93 was 8.8 min with a
z value of 9.1±0.3 °C. For the high-acid fruit products, the target
P-value was equivalent to 5 min at 85 °C (
T
ref=85 °C,
z=10 °C). Amylase activity before and after processing was converted to
P-values, with all of the processes showing a substantial safety margin, despite operating conditions that were deliberately set to represent the ‘worst case’ conditions. This method allowed
P-value data to be collected under conditions that prevented the use of thermocouples.
An innovative method developed for fruit content determination based on the quantification of hemicellulose was applied to apricot and peach fruit preparations, apricot and strawberry jams and ...spreads. For this purpose, the hemicellulose fraction was isolated from the alcohol-insoluble residue from peaches, apricots, and strawberries, yielding the amount of the respective fresh fruit per gram hemicellulose. Fruit preparations from peaches with 34.4%, 47.2% and 66.4% fruit content were produced using pectin and carrageenan, xanthan or starch, respectively, as hydrocolloids. Jams from apricots and strawberries were prepared with pectin. Fruit contents of apricot jams were 34.1% and 48.2%, and 36.6% and 46.4% in strawberry jams, respectively. Furthermore, a range of commercial apricot spreads and jams and one strawberry spread as well as apricot and peach fruit preparations were examined. The fruit content was calculated based on the amount of hemicellulose. Calculated fruit contents were in good agreement with the respective product specifications (e.g. 62.6% vs. 66.4%, 35.2% vs. 34.1%, 67.5% vs. 70.0% and 54.0% vs. 53.7%, respectively) with deviations ranging between 0.3% and 4.2%. Maximal deviation was found only in the case of a self-made peach fruit preparation (40.9% vs. 34.4%), where interference of added hydrocolloids and fruit ingredients probably resulted in significant overestimation of the fruit content. Although sample preparation needed to be adapted to different fruit matrices, this novel method proved to be suitable for the determination of fruit contents of fruit preparations, spreads and jams. For the first time, this method was successfully applied to industrially manufactured fruit products without knowledge of fruit specification and the complex recipes of jams, spreads, and fruit preparations, respectively.
A method recently developed for the determination of the fruit content of strawberry fruit preparations by gravimetric quantification of hemicellulose was extended to cherry fruit preparations. ...Isolation of the alcohol-insoluble residue (AIR) and sequential fractionation of the cell wall compounds from cherries (
Prunus cerasus L. cv. ‘Oblacinska’) was performed yielding the amount of fresh cherries per gram hemicellulose. Cherry fruit preparations with varying fruit contents (30–40%) were produced using different hydrocolloid systems (pectin, starch, guar gum, xanthan gum, carrageenan, and combinations thereof). After separation of the hydrocolloids by enzymatical digestion and successive extraction, the fruit preparations were subjected to AIR isolation. The AIR was fractionated to yield the hemicellulose fraction, which was quantified gravimetrically for the calculation of the fruit content. Compared to strawberries, modifications including additional extraction steps for the sequential fractionation were required to separate the pectin of the cherries exhaustively. Calculated and initial fruit contents were in good agreement for the single hydrocolloid components pectin and starch as well as for the combinations pectin/xanthan gum and pectin/carrageenan (26.8% vs. 30%, 38.6% vs. 40%, 42.5% vs. 40%, 37.6% vs. 40%, and 41.2% vs. 40%), whereas the preparations produced with more complex hydrocolloid systems (pectin/xanthan gum/guar gum and starch/xanthan/guar gum) showed larger deviations in their contents (46.2% vs. 40%, 49.6% vs. 40%). It is concluded that the novel method is generally suitable for the determination of the fruit content of fruit preparations, but steps of sample preparation need to be individually adapted to the different fruit matrices.
A novel method for the determination of the fruit content of strawberry fruit preparations based on the quantification of hemicellulose is presented. For this purpose, the hemicellulose fraction was ...isolated from the alcohol-insoluble residue (AIR) of strawberry fruits (
Fragaria
×
ananassa cv. ‘Senga Sengana’ and ‘Camarosa’) to calculate the amount of fresh fruit per gram hemicellulose. Fruit preparations with fruit contents ranging from 30% to 60% were produced using starch, pectin, xanthan and guar gum as hydrocolloids. For the determination of the fruit content, added hydrocolloids were removed by enzymatic digestion and alkaline degradation, respectively. The hemicellulose fraction resulting from AIR fractionation was quantified gravimetrically. Due to the characteristic composition of neutral sugars obtained after hydrolysis, the hemicellulose fractions may be used for authenticity control. Excellent agreement between specified and determined contents (30% vs. 31.5%; 45% vs. 44.7%; 60% vs. 64%; 40% vs. 37.6–42.2%) was obtained irrespective of the composition of the fruit preparation. This method is considerably more reliable than those based on the determination of low-molecular compounds which can easily be added to feign a higher fruit content. Furthermore, fruit juice concentrates added to fruit preparations as a food colorant do not affect the quantification of the fruit content.
Yogurt O'Rell, Kevin; Chandan, Ramesh C
Manufacturing Yogurt and Fermented Milks,
03/2013
Book Chapter
This chapter contains sections titled:
Introduction
Fruit as a raw material for yogurt preparations
Processing of fruit for use in yogurt fruit preparations
Formulation of fruit preparations
...Processing yogurt fruit preparations
Packaging of fruit preparations
Acknowledgment
References and further reading
PDF
