Quality and Acceptability of Microwave and Conventionally Pasteurised Kiwifruit Puree

Effect of continuous microwave processing on enzymes and quality attributes of bael beverage

Bael (Aegle marmelos) beverage was pasteurized using continuous-microwave (MW) and traditional thermal processing and the activity of native enzymes, pulp-hydrolyzing enzymes, bioactive, physicochemical, and sensory properties were analyzed. First-order and linear biphasic models fitted well (R2 ≥ 0.90) for enzyme inactivation and bioactive alteration kinetics, respectively. For the most resistant enzyme, polyphenoloxidase (PPO), the inactivation target of ≥ 90 % was achieved at 90 °C TMW (final temperature under MW) and 95 °C for 5 min (conventional thermal). MW treatment displayed faster enzyme inactivation and better retention of TPC and AOC. MW treatment at 90 °C TMW showed 5.3 min D-value, 90% total carotenoid content, 3.42 crisp sensory score (out of 5), and no or minor change in physicochemical attributes. Thermal and MW treatment caused the loss of 14 and 10 bioactive compounds, respectively. The secondary and tertiary structural modifications of PPO enzyme-protein revealed MW's lethality primarily due to its thermal effects.

Toward in-process technology-aided automation for enhanced microbial food safety and quality assurance in milk and beverages processing

Ensuring the safety of food products is critical to food production and processing. In food processing and production, several standard guidelines are implemented to achieve acceptable food quality and safety. This notwithstanding, due to human limitations, processed foods are often contaminated either with microorganisms, microbial byproducts, or chemical agents, resulting in the compromise of product quality with far-reaching consequences including foodborne diseases, food intoxication, and food recall. Transitioning from manual food processing to automation-aided food processing (smart food processing) which is guided by artificial intelligence will guarantee the safety and quality of food. However, this will require huge investments in terms of resources, technologies, and expertise. This study reviews the potential of artificial intelligence in food processing. In addition, it presents the technologies and methods with potential applications in implementing automated technology-aided processing. A conceptual design for an automated food processing line comprised of various operational layers and processes targeted at enhancing the microbial safety and quality assurance of liquid foods such as milk and beverages is elaborated.

Impact of sugar replacement by non-centrifugal sugar on physicochemical, antioxidant and sensory properties of strawberry and kiwifruit functional jams

Raw cane sugars have been claimed to be rich in natural phenolic compounds which, in contrast to refined sugar, may increase the nutritional value of foods and contribute to the development of healthier foods and diets. The use of non-refined cane sugars in food formulation seems an interesting option since they provide natural antioxidants with sucrose still being the major sugar present, minimizing the loss of technological properties. However, substitution of refined sugar could imply an undesired impact on physicochemical and sensory properties, conditioning consumer's acceptance. Functional jams (strawberry and kiwifruit) with a larger fruit to sugar ratio than conventional ones, in which white sugar was replaced by granulated jaggery (0, 15, 30, 45, 60 y 75 % w/w) were obtained. Impact of sugar replacement was assessed by evaluating physicochemical properties (moisture, water activity, pH, total soluble sugars, sugar profile (glucose, fructose, sucrose), and optical, rheological, mechanical and antioxidant properties). Sensory properties and microbiological stability were also determined. Jaggery improved the antioxidant properties of jams (total phenolic content, total flavonoid content, antiradical activity by the DPPH and ABTS methods), proportionally to the amount of cane sugar incorporated and more significantly in the case of kiwifruit. Other physicochemical properties were not significantly affected by jaggery, except for color. However, these differences were not crucial in the acceptability tests, since acceptance of jams containing jaggery was generally good, very good when intermediate replacement percentages were used. Conclusions of the present work suggest that granulated jaggery can be used to formulate sugar-rich food products such as jams in order to increase their nutritional value, with little impact on physicochemical properties and good consumer acceptance.

Microwave flow and conventional heating effects on the physicochemical properties, bioactive compounds and enzymatic activity of tomato puree

BACKGROUND

Thermal processing causes a number of undesirable changes in physicochemical and bioactive properties of tomato products. Microwave (MW) technology is an emergent thermal industrial process that offers a rapid and uniform heating, high energy efficiency and high overall quality of the final product. The main quality changes of tomato puree after pasteurization at 96 ± 2 °C for 35 s, provided by a semi-industrial continuous microwave oven (MWP) under different doses (low power/long time to high power/short time) or by conventional method (CP) were studied.

RESULTS

All heat treatments reduced colour quality, total antioxidant capacity and vitamin C, with a greater reduction in CP than in MWP. On the other hand, use of an MWP, in particular high power/short time (1900 W/180 s, 2700 W/160 s and 3150 W/150 s) enhanced the viscosity and lycopene extraction and decreased the enzyme residual activity better than with CP samples. For tomato puree, polygalacturonase was the more thermo-resistant enzyme, and could be used as an indicator of pasteurization efficiency.

CONCLUSION

MWP was an excellent pasteurization technique that provided tomato puree with improved nutritional quality, reducing process times compared to the standard pasteurization process. © 2016 Society of Chemical Industry.

Red fresh vegetables smoothies with extended shelf life as an innovative source of health-promoting compounds

Two fresh red vegetables smoothies based on tomato, carrots, pepper and broccoli and rich in health-promoting compounds were developed. The smoothies showed a viscoelastic behaviour. According to sensory analyses, a shelf life of 28 days at 5 °C for fresh blended smoothies was established while thermally-treated ones (3 min, 80 °C) reached up to 40 days at 20 °C and 58 days at 5 °C. For those mild heat treated smoothies, total vitamin C degradation was 2-fold reduced during storage at 5 °C compared to samples stored at 20 °C while the initial total carotenoids, lycopene and total chlorophylls contents were not greatly affected. A 250-g portion of such smoothies covers in a great extend the established recommended daily nutrient intakes for dietary fibre, minerals and vitamin C of different population groups. As main conclusion, a mild thermal treatment and low temperature storage greatly increased the shelf life of red fresh vegetables smoothies and reduced total vitamin C degradation.