Band 15, Heft 11-12 -

Kinetic models describing the thermal inactivation of peroxidase and degradation of broccoli ( Brassica Oleracea var. Italica ) color were coupled with heat transfer equation (2D conductive heat transfer in cylindrical packed broccoli samples), and their simultaneous numerical simulation followed by experimental validation was carried out. Obtained results revealed that modeling the rate constants of the reactions with log logistic equation provides a better prediction in comparison with the most popular Arrhenius equation. It was observed that processing at temperatures lower than 80 °C is not recommended for processing of broccoli due to its adverse effect on the color of samples and considerable longer process time needed for assuring sufficient inactivation of enzyme at the cold spot. Temperatures above 80 °C were suitable for this purpose because the process time needed for inactivating peroxidase at the cold spot of sample not only affected the green color of samples negatively, but oppositely it resulted in a higher greenness than the original value.

Fresh fruit juice has a short storage period and it usually needs to be concentrated for shelf-life extension. Evaporation of fruit juice is an attractive method and vertical tube falling film evaporator is one of good choice. The main problem in the design of the evaporator is the reliable estimation of the heat transfer coefficient for all effects. In this paper, the effects of feed flow rate, evaporation temperature, temperature difference, and juice soluble solid content on heat transfer coefficient of a vertical falling film evaporator were investigated. The Bayesian treed Gaussian process model was used to identify the key variables affecting the heat transfer coefficient, which showed that evaporation temperature had the greatest influence on the sensitivity of heat transfer coefficient. It also demonstrated that complex interactions existed between the four operating parameters had a significant effect on the overall heat transfer coefficient.

Avocado puree demand grows with the rise in demand for fruit flavors and healthy food consumption. The aim of this research was to produce a minimally processed fruit puree that retain the color during 6 months of frozen storage and assess a preliminary economic and environmental approach for its industrial production. Mashed avocado pulp was mixed with lemon juice for obtaining raw avocado puree. This material was then mixed with citric acid or exposed to a microwave treatment to obtain Citric acid puree (CAP) and microwave-treated puree (MWP). CAP and MWP were submitted to frozen storage (–10 °C, –14 °C and –18 °C), and each 30 days puree samples were tested for Polyphenol oxidase (PPO) and Peroxidase (POD) activity and color. While PPO was completely inhibited, POD exhibited sharp reductions, especially for the MWP. Almost all the samples preserved their original color. Economic and environmental impacts were evaluated for a CAP production process.

This study was performed to investigate the cooking characteristics and sensory evaluation of rice cooked in the presence of 20 % germinated barley. The soluble solid and water absorption rate increased significantly with longer barley germination periods. The microstructure of the cooked germinated barley showed some pores 4 days after germination and increased pore numbers and size 6 days after germination. The hardness of cooked-rice tended to decrease after germination of barley. Sensory evaluation indicated that barley germinated for 2–4 days is the most suitable (overall acceptance) for cooking. These results indicate that pores are formed on the surface during the germination of barley, so that water is easily absorbed during cooking and the hardness is low, and the texture of barley is improved even when rice is cooked. This study suggests that rice cooked with germinated barley has improved sensory characteristics, without unnecessary processing (milling, chopping, or pressing) the barley.

To evaluate the non-Newtonian viscosities of liquid foods thickened for assistance of swallowing in nursing-care practice, an inclined flow channel instrument was investigated for development into a structurally simple and easy-to-use viscometer. Experimental analysis of the flows of Newtonian and non-Newtonian test liquids in the instrument derived a dimensionless relation expressing changes of the friction coefficient in the flow process which was indicated by the relative flow length, considering the shear rate level in the swallowing process. A methodology to evaluate uniquely the viscosities of liquid foods undergoing the swallowing process was presented using the measurements such as the flow length and velocity in the instrument.

Enrichment of snack foods with plant ingredients has become very popular. Corn extrudates with fresh kale leaves are an example of a healthy snack food. During the study, these snacks were produced by extrusion-cooking and contained from 5 % to 20 % of fresh kale leaves in their recipe. For the obtained extrudates, the following parameters were determined: extrusion efficiency, specific mechanical energy requirement, bulk density, specific density, water absorption index, water solubility index, radial expansion ratio, cutting force, as well as the color coordinates on the CIE-Lab scale. It was observed that the addition of fresh kale leaves led to a significant decrease in processing efficiency as well as the expansion ratio, water solubility index and brightness of supplemented snacks. Increased density, cutting force and greenness of snacks was observed with increasing amounts of kale in the recipe.

The effect of heating at different temperatures (60, 80, 90, 110, and 130 °C) on the total phenolic content, antioxidant activity, and phenolic compounds present in plum and mahaleb fruits was investigated. The antioxidant activity values and total phenolic contents of fresh plum (93.82% measured by DPPH method, 787.79 mg gallic acid equivalent (GAE)/100 g dry weight determined by Folin method) and mahaleb fruits (81.80%, 634.47 mg GAE/100 g dry weight) were higher than plum and mahaleb fruits dried at different temperatures ( p  < 0.05). Generally, the heating process caused a reduction in both total phenolic content and antioxidant activity for plum and mahaleb. While (+)-catechin (92.62 mg/kg), 1,2-dihydroxybenzene (132.15 mg/kg), gallic acid (107.01 mg/kg), and 3,4-dihydroxybenzoic acid (74.59 mg/kg) are the key phenolic compounds in fresh plum, (+)-catechin, 3,4-dihydroxybenzoic acid, 1,2-dihydroxybenzene, and syringic and caffeic acids were the major phenolic compounds of mahaleb fruits. The polyphenol content of fruits and the class of phenolics present are significantly affected by heating temperature.

The aim of this study was to determine the influence of sloe berry (SB) addition at different ratios on the physical, chemical, antioxidant, colour and sensory properties and mineral contents of ice creams. The increment of SB led to the an increase of titratable acidity, overrun, viscosity and ash values, first dripping and complete melting times; in contrast, it decreased the total solid, pH and fat values. Mn and Zn values were affected significantly ( P  < 0.05) by the addition of SB but other element levels were not affected. L* and b* values decreased significantly in all samples as compared with control sample, while a* , H° , C* and ∆ E* increased significantly with addition of SB. Antioxidant activity was the highest in the sample containing 15 % SB (w/w) among ice cream samples. The ice cream samples containing 15 % SB had higher score than the control sample in terms of colour and appearance, gumming structure and general acceptability.