Modelling and Optimization of the Processing of a Healthy Snack Bar Made of Grape and Tomato Pomaces

A snack made of 36% by byproducts of grape and tomato pomaces was developed, also including other ingredients, such as oats, chia, quinoa, honey and peanut butter. The recipe was defined as tasty and healthy by a focus group. The snack was produced by using forced air at three different drying temperatures (50 °C, 60 °C and 70 °C). The Newton, Page, Henderson and Pabis, and Midilli-Kucuk models fit the drying curves well. The average values for the Newton's model drying constants were k50 = 2.71 × 10-1 ± 3 × 10-3 min-1, k60 = 2.76 10-1 ± 4 × 10-3 min-1 and k70 = 3.91 × 10-1 ± 8 × 10-3 min-1 at 50 °C, 60 °C and 70 °C, respectively. The product's quality was assessed in terms of storage with respect to water activity and texture (hardness, springiness, cohesiveness, chewiness and resilience). There were no differences among the three tested processing temperatures in terms of their influence the final product's quality. As there were no significant differences between initial and final water activity and texture attributes at any temperature and they were mainly unaltered during storage, the snack bar was considered stable during this period. This new snack, which includes byproducts from the food industry, reduces food waste and contributes to a circular economic model, simultaneously presenting environmental and economic advantages.

Nutritional, phytochemical composition and potential health benefits of taro (Colocasia esculenta L.) leaves: A review

Colocasia esculenta(L) or taro is a tropical crop largely produced for its tubers (corms) while leaves and stems remain underutilized and untapped by-products with promising potential applications.Colocasialeaves are low in calories, rich in proteins, dietary fiber, and micronutrients. However, its utilization as food remains limited owing to the lack of awareness vis-à-vis its nutritional profile and the presence of antinutrients such as tannins, phytates and oxalates. The antinutritional factors can be overcome by cooking and varied processing techniques thereby unveiling the nutritional benefits. The high content of bioactive compounds and antioxidative potential of colocasia leaves renders several health benefits such as anticancer, antidiabetic, anti-inflammatory activity. The paper reviews the available literature on the nutritional, antinutritional, phytochemical profile of taro leaves and the advanced analytical techniques for their identification and quantification. Further, its health benefits and food applications have been discussed.

Secondary product from strawberry (Fragaria ananassa) fruit for extended preservation and value addition

Strawberry is highly delicate and perishable fruit prone to microbial spoilage. To address these issues, secondary product(s) using strawberry pulp was prepared by adding sweetener (jaggery or sucrose) and anti-browning agent (citrate) to reduce the extent of drying induced sourness and discoloration, respectively. Subsequently, these products were LDPE packed and radiation processed (≤ 5 kGy) to ensure microbiological safety during ambient temperature storage. Physical, biochemical, functional (antioxidant and antimutagenic) and organoleptic properties (including flavor compounds) were found to be either retained or enhanced compared to dehydrated strawberry pulp. The product termed as dehydrated strawberry roll having jaggery and citrate (DSRJ) was found to be more acceptable than that having sucrose and citrate (DSRS) till 5 months. Scanning electron microscopy indicated better surface quality of DSRJ than DSRS. Electrochemical property when analyzed using cyclic voltammetry displayed strong correlation to radical scavenging antioxidant assays with marginal storage associated shift in the peak potential. GC-MS analysis indicated retention of most of the flavor compounds in DSRJ during storage. Thus, DSRJ, a value-added product could provide a solution to control post-harvest losses of the fruit by processing to a more stable form and ensuring availability beyond the season.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13197-021-05171-9.

The Influence of Vacuum Impregnation on Nutritional Properties of Fluidized Bed Dried Kale (Brassica oleracea L. Var. Acephala) Leaves

The aim of the work was to assess the possibility of obtaining high bioactivity dried kale using a vacuum impregnation as the preliminary processing before the drying. Kale leaves underwent vacuum impregnation in freshly squeezed onion juice and in sodium chloride solution utilising the following impregnation process parameters: At the vacuum stage, 6 kPa reduced pressure for 1 min, dosing the impregnating solution and keeping the sample under vacuum for 2 min, and then 6 min in impregnating solution at atmospheric pressure. Fluidized bed drying of kale was conducted using inert polypropylene balls, utilising a drying air temperature in a range from 70 to 130 °C. The drying kinetics were described, and the dehydrated product’s quality was assessed, on the basis of these selected characteristics: The content of chlorophylls, polyphenols and carotenoids, and antioxidant activity measured with ABTS⁺, dry matter, water activity and colour. It was determined that protective influence of vacuum impregnation before fluidized bed drying was seen only in the case of using temperatures of 90 and 110 °C. The highest content of bioactive components in dried kale was obtained in the case of using onion juice impregnation and drying at 110 °C.