High-Pressure Processing vs. Thermal Treatment: Effect on the Stability of Polyphenols in Strawberry and Apple Products

Effects of high hydrostatic pressure processing on the physicochemical properties, functional characteristics, and antioxidant activity of silkworm pupae protein

With the rising demand for sustainable proteins, edible insects such as silkworm pupae are gaining recognition for their high-quality protein and essential nutrients. Advanced technologies like high hydrostatic pressure (HHP) processing have the potential to enhance the functional properties of insect proteins. This study investigated the application of HHP to silkworm pupa protein, focusing on its effects on physicochemical properties, functional characteristics, and bioactivity. HHP treatments at 400 and 600 MPa significantly enhanced emulsifying and foaming capacities, as well as antioxidant activity. Furthermore, HHP-assisted extraction facilitated protein unfolding and increased the exposure of hydrophobic groups on the protein surface, which likely contributed to improvements in protein solubility and antioxidant function. These findings provide valuable insights into the potential of HHP to enhance the quality of edible insect proteins for food applications.

An insight into the full aspects of bound polyphenols in dietary fiber: Interaction, composition, function and foundation as well as alteration in food processing

Dietary fiber (DF) and polyphenols are both bioactive compounds with various health-promoting effects while close relationship between them aroused wide concern in recent years. Abundant polyphenols combine with DF and contribute greatly to its beneficial effects. Although efforts made to uncover such bound polyphenols (BPs) from different angles before, systematic overview of full aspects is deficient. Here, more details about polyphenols conjugated in DF reported recently were summarized systematically. Meanwhile, the disposition of BPs in gastrointestinal tract and their interaction with microbiome were introduced to clarify the foundation of their functions. Moreover, considering the great impacts of food processing on polyphenols, different technics used in food handling were introduced with their effects on BPs emphatically discussed to provide guideline for reasonable application of specific technics for given materials. Our work is supposed to promote the understanding of BPs in DF and facilitate their future exploitation and application as a whole.

Dietary Polyphenols, Food Processing and Gut Microbiome: Recent Findings on Bioavailability, Bioactivity, and Gut Microbiome Interplay

Polyphenols are organic chemical compounds naturally present in plants, renowned for their anti-inflammatory, antioxidant, immunomodulatory, anticancer, and cardiovascular protective properties. Their bioactivity and bioavailability can vary widely depending on the methods of food processing and interactions with the gut microbiome. These factors can induce changes in polyphenols, affecting their ability to achieve their intended health benefits. Thus, it is essential to develop and apply food processing methods that optimize polyphenol content while maintaining their bioactivity and bioavailability. This review aims to explore how various food processing techniques affect the quantity, bioactivity, and bioavailability of polyphenols, as well as their interactions with the gut microbiome, which may ultimately determine their health effects.

Monitoring effects on anthocyanins, non-anthocyanin phenolics and ORACFL values of Colombian bilberry (V. meridionale Swartz) during pulping and thermal operations

Processing of berries usually degrades anthocyanin and non-anthocyanin phenolics and diminishes antioxidant activity. In Colombia, jelly produced from the fruit of Vaccinium meridionale Swartz is a popular product among consumers. The aim of this study was to determine the effect of jelly processing steps on bioactive components. Analysis of anthocyanins (ACNs) and non-anthocyanin phenolics was performed via HPLC-PDA. Antioxidant activity was assessed by the ORACFL method. The pulping step had the highest impact on ACNs, whose total content was significantly higher in the pomace (747.6 ± 59.2 mg cyanidin 3-glucoside (cyn 3-glu)/100 g) than in the pulp (102.7 ± 8.3 mg cyn 3-glu/100 g). Similarly, pulping caused a significant decrease in flavonols, procyanidins (PACs) and ORACFL values. Despite the effects of processing, Colombian bilberry jelly can be considered a good source of phenolic compounds with high antioxidant activity. The final concentration of ACNs, hydroxycinnamic acids (HCAs) and flavonols, as well as the ORACFL values in this product were comparable to those of fresh cranberry (Vaccinium oxycoccos) and black currant (Ribes nigrum). The results also suggest that the pomace of V. meridionale can be recovered as an excellent source of bioactive compounds.

Advances in strawberry postharvest preservation and packaging: A comprehensive review

Strawberries spoil rapidly after harvest due to factors such as the ripening process, weight loss, and, most importantly, microbial contamination. Traditionally, several methods are used to preserve strawberries after harvest and extend their shelf life, including thermal, plasma, radiation, chemical, and biological treatments. Although these methods are effective, they are a concern from the perspective of safety and consumer acceptance of the treated food. To address these issues, more advanced environment-friendly technologies have been developed over the past decades, including modified and controlled atmosphere packaging, active biopolymer-based packaging, or edible coating formulations. This method can not only significantly extend the shelf life of fruit but also solve safety concerns. Some studies have shown that combining two or more of these technologies can significantly extend the shelf life of strawberries, which could significantly contribute to expanding the global supply chain for delicious fruit. Despite the large number of studies underway in this field of research, no systematic review has been published discussing these advances. This review aims to cover important information about postharvest physiology, decay factors, and preservation methods of strawberry fruits. It is a pioneering work that integrates, relates, and discusses all information on the postharvest fate and handling of strawberries in one place. Additionally, commercially used techniques were discussed to provide insight into current developments in strawberry preservation and suggest future research directions in this field of study. This review aims to enrich the knowledge of academic and industrial researchers, scientists, and students on trends and developments in postharvest preservation and packaging of strawberry fruits.

Enhancing the Stability of Strawberry Anthocyanins Complexed to β-Cyclodextrin and Starch toward Heat, Oxidation, and Irradiation

The instability of anthocyanins limits their application in food supplementation and in the food industry. Stabilities of strawberry anthocyanins (AN) were improved by complexation with both β-CD and starch against heat, H2O2, light, and UV irradiation. The stability of AN against H2O2 (2.21 mM) dropped (<20%) in 6 h but was enhanced in β-CD (49.32%) and starch (96.84%) complexes. Under light conditions, AN in the solid and solution (3.88 g/100 mL) forms degraded to 36.49 and 11.11%, while β-CD and starch complexes displayed stabilities of 98.20 and 91.76%, respectively, after 60 days. Under UV irradiation, AN showed similar instability where both AN forms expressed stabilities of 36.75 and 66.18%, respectively, after 168 h, while β-CD and starch complexes exhibited 51.13 and 40.10%, respectively. LC-MS-ESI showed that photoirradiation of both destroyed the full conjugation of the flavylium ring of the major components, pelargonidin and cyanidin hexoses; the mechanism was proposed. Docking binding models of major AN components in β-CD were obtained.

Identification and stability evaluation of polyphenol oxidase substrates of pineapple fruit

Pineapple as an important tropical fruit in the world is prone to internal browning (IB) caused by the oxidation of phenolic substances. To address the occurrence of IB, endogenous polyphenol oxidase (PPO) substrates were extracted, separated, and purified from pineapple fruit, and then four compounds were obtained and identified as catechin, epicatechin, chlorogenic acid and pyrocatechol. The contents of these substrates increased, reached the maximum value in the middle storage period, decreased gradually, and then maintained a relatively stable level by the end of storage. Meanwhile, pineapple PPO substrates were unstable in structure and susceptible to be degraded under the condition of light, high temperature (>40 °C), alkalinity (pH > 9) or metal ion (Ca2+, Cu2+, Fe2+, Pb2+ and Zn2+). Additionally, the presences of O2 and H2O2 increased the enzymatic oxidation of the pineapple PPO substrates, whereas CO2, N2, Vc (Vitamin C), l-cysteine, Na2SO3 and Na2S2O5 inhibited this oxidation.

High-efficiency fungal pathogen intervention for seed protection: new utility of long-chain alkyl gallates as heat-sensitizing agents

Control of food-contaminating fungi, especially pathogens that produce mycotoxins, is problematic since effective method for intervening fungal infection on food crops is often limited. Generally Regarded As Safe (GRAS) chemicals, such as natural compounds or their structural derivatives, can be developed as antimicrobial agents for sustainable food/crop production. This study identified that long-chain alkyl gallates, i.e., octyl-, nonyl-, and decyl gallates (OG (octyl 3,4,5-trihydroxybenzoic acid), NG, DG), can function as heat-sensitizing agents that effectively prevent fungal contamination. Out of twenty-eight candidate compounds and six conventional antifungal agents examined, the heat-sensitizing capacity was unique to the long-chain alkyl gallates, where OG exhibited the highest activity, followed by DG and NG. Since OG is a GRAS compound classified by the United States Food and Drug Administration (FDA), further in vitro antifungal studies were performed using OG. When OG and mild heat (57.5°C) were co-administered for 90 seconds, the treatment achieved > 99.999% fungal death (> 5 log reduction). Application of either treatment alone was significantly less effective at reducing fungal survival. Of note, co-application of OG (3 mM) and mild heat (50°C) for 20 minutes completely prevented the survival of aflatoxigenic Aspergillus flavus contaminating crop seeds (Brassica rapa Pekinensis), while seed germination rate was unaffected. Heat-sensitization was also determined in selected bacterial strains (Escherichia coli, Agrobacterium tumefaciens). Altogether, OG is an effective heat-sensitizing agent for control of microbial pathogens. OG-mediated heat sensitization will improve the efficacy of antimicrobial practices, achieving safe, rapid, and cost-effective pathogen control in agriculture/food industry settings.

Use of HPLC-MS to Determine the Loss of Metabolites in Apple Juices under Different Storage Conditions

The focus of this experiment was to compare the color and metabolic profile of apple juice from the red-fleshed cultivar 'Baya Marisa' with the white-fleshed cultivar 'Golden Delicious'. The changes in the phenolic compounds, organic acids, and sugar content during high-temperature short-time pasteurization and after one year of storage under different storage conditions were analyzed. A total of 26 individual phenolic compounds were identified and quantified. The total analyzed phenolics content (TAPC) decreased after pasteurization of the juices of both cultivars. The TAPC of fresh 'Baya Marisa' juice after pasteurization increased or remained the same compared to one-year stored 'Baya Marisa' juice, depending on the storage method. The sucrose content of the apple juice of both cultivars remained the same after pasteurization; interestingly, it decreased significantly after one year of storage, while the fructose and glucose content remained the same after pasteurization and increased significantly after one year of storage for both cultivars.

Using HPLC-MS/MS to Determine the Loss of Primary and Secondary Metabolites in the Dehydration Process of Apple Slices

The aim of this study was to compare peeled and unpeeled dehydrated apple slices of the red-fleshed ‘Baya Marisa’ and the white-fleshed ‘Golden Delicious’, to analyze the difference in the content of sugars, organic acids, and phenolic compounds during the heat process of dehydration, and to compare it with our previous study on fresh apples of the same cultivar. The purpose of these study was to see how many primary and secondary metabolites are lost in the dehydration process to better understand what is ingested by consumers in terms of nutritional value. A total of 30 phenolic compounds were identified and quantified, some of them for the first time. The total analyzed phenolic content (TAPC) of the unpeeled dehydrated apple slices was 1.7 times higher in ‘Golden Delicious’ than in ‘Baya Marisa’. The unpeeled dehydrated apple slices of ‘Golden Delicious’ had higher total hydroxycinnamic acid (2.7×) and dihydrochalcone (1.2×) content. The peeled dehydrated apple slices of ‘Baya Marisa’ had higher total dihydrochalcone (2.2×) and total flavanol (2.2×) content compared to ‘Golden Delicious’. The content of citric and malic acids was higher in the unpeeled and peeled dehydrated apple slices of ‘Baya Marisa’, compared to ‘Golden Delicious’. The content of ascorbic acid was higher in the unpeeled (1.6×) and peeled (1.8×) dried apple slices of ‘Baya Marisa’. The content of fructose and glucose was 1.4 times higher in the unpeeled dried apple slices of ‘Golden Delicious’.

Effect of Storage Conditions on the Stability of Polyphenols of Apple and Strawberry Purees Produced at Industrial Scale by Different Processing Techniques

During a food product's life, storage conditions affect its composition of nutrients, bioactive compounds, and sensory attributes. In this research, strawberry and apple purees were selected as a model to examine how the storage of various purees industrially produced with different technologies affect the bioactive phenolic compounds, color, and sensory attributes. Specifically, fruit products processed on an industrial scale by different technologies including freezing, thermal treatment (mild and standard), and high-pressure processing were studied, as well as storage for up to 12 months at -20, 4, and 24 °C. In strawberry puree, storage conditions had a stronger impact on phenolic compound levels, particularly on anthocyanins, whereas in apple puree, the initial processing techniques exerted a greater influence than storage conditions, mainly caused by the hot or cold crushing processes. In general, proanthocyanidins were the major phenolic group and the most stable during storage, while anthocyanins were the group most affected by both processing and storage. Apple flavonols and dihydrochalcones were quite stable, while strawberry ellagitannins suffered higher degradations during storage. Through our analysis, it is found that during storage, the stability of polyphenols in each fruit is different, and processing and storage can be either detrimental or even beneficial. The selection of the ideal storage conditions (time and temperature) is a key factor to maintaining the polyphenol content in sensitive fruits such as strawberries. However, storage conditions are in some cases more important to minimizing the polyphenol losses than how the product is processed.

Thermal and Non-Thermal Treatments to Preserve and Encourage Bioactive Compounds in Fruit- and Vegetable-Based Products

Fruit- and vegetable-based products (F&Vs) have been conventionally processed using thermal techniques such as pasteurization, scalding, or/and drying, ensuring microbial safety and/or enzyme deactivation [...].

Untargeted Metabolomics Reveals New Markers of Food Processing for Strawberry and Apple Purees

In general, food processing and its conditions affect nutrients, bioactive compounds, and sensory characteristics of food products. This research aims to use a non-targeted metabolomics approach based on UPLC-ESI-QTOF-MS to determine how fruit processing can affect the metabolic profile of fruits and, through a comprehensive metabolic analysis, identify possible markers to assess their degree of processing. The present study uses a real case from the food industry to evaluate markers of the processing of strawberry and apple purees industrially elaborated with different processing techniques and conditions. The results from the multivariate analysis revealed that samples were grouped according to the type of processing, evidencing changes in their metabolic profiles and an apparent temperature-dependent effect. These metabolic profiles showed changes according to the relevance of thermal conditions but also according to the exclusively cold treatment, in the case of strawberry puree, and the pressure treatment, in the case of apple puree. After data analysis, seven metabolites were identified and proposed as processing markers: pyroglutamic acid, pteroyl-D-glutamic acid, 2-hydroxy-5-methoxy benzoic acid, and 2-hydroxybenzoic acid β-d-glucoside in strawberry and di-hydroxycinnamic acid glucuronide, caffeic acid and lysoPE(18:3(9Z,12Z,15Z)/0:0) in apple purees. The use of these markers may potentially help to objectively measure the degree of food processing and help to clarify the controversial narrative on ultra-processed foods.

Stability of polyphenols in food processing

In recent years, polyphenols have attracted considerable attention due to their diverse potential health-beneficial effects on humans. Polyphenols are widely distributed in natural plants, and therefore play an important role in human food. Thermal processing, irradiation, fermentation, high pressure, microwave, and drying are several popular food processing methods. However, polyphenols are instable in food processing, which easily degrade and react with other components because of their polyhydroxy characteristic. Traditional and advanced technologies have been used to characterize the stability of polyphenols. The main influence factors of stability of polyphenols such as pH, temperature, light, oxygen, enzymes, metal ions, as well as macromolecules, are summarized. Besides, thermal processing greatly promoted the degradation of polyphenols. Thermal degradation mechanisms and products of some polyphenols, such as quercetin and rutin, have been intensively demonstrated. Nevertheless, the structural changes of polyphenols caused by food processing, may lead to different bioactivities from the obtained results based on unprocessed polyphenols. Therefore, to maximize the beneficial effects of polyphenols ingested by human from processed food, the stability of polyphenols in food processing must be thoroughly investigated to assess their real bioactivities. In addition, some available technologies for improving the stability of polyphenols in food processing have been proposed.

Lactate content, total polyphenols and antioxidant activity of selected commercial yogurts from the Serbian market

One of the most popular dairy products worldwide is yogurt, which flavor is highly influenced by lactic acid content. Yogurts with fruit preparations contain polyphenols, secondary plant metabolites with proven antioxidant properties. As there is no data regarding neither lactate nor polyphenol content in commercial yogurts in Serbia, this study aimed to determine lactate and polyphenol levels, as well as antioxidant activity in selected yogurts. A total of 15 plain and 5 fruit yogurts with strawberry preparations were analyzed. Lactate contents were from 0.83 to 1.33%. Three plain yogurts in plastic containers differed in lactate content. There was no difference in lactate content among the same plain yogurts packed in plastic and Tetra Pack containers. Fruit yogurts with strawberry preparations differed in total polyphenol content in the range from 6.84 to 29.11mg GAE/100 g and antioxidant properties were determined by reducing power test (from 0.22 to 0.79) and DPPH assay (from 28.13 to 87.23%), while there was no difference regarding lactate. Our results provided new information about the levels of lactate, total polyphenols and antioxidant activity of selected commercial yogurts available on the Serbian market.

Lactate content, total polyphenols and antioxidant activity of selected commercial yogurts from the Serbian market

One of the most popular dairy products worldwide is yogurt, which flavor is highly influenced by lactic acid content. Yogurts with fruit preparations contain polyphenols, secondary plant metabolites with proven antioxidant properties. As there is no data regarding neither lactate nor polyphenol content in commercial yogurts in Serbia, this study aimed to determine lactate and polyphenol levels, as well as antioxidant activity in selected yogurts. A total of 15 plain and 5 fruit yogurts with strawberry preparations were analyzed. Lactate contents were from 0.83 to 1.33%. Three plain yogurts in plastic containers differed in lactate content. There was no difference in lactate content among the same plain yogurts packed in plastic and Tetra Pack containers. Fruit yogurts with strawberry preparations differed in total polyphenol content in the range from 6.84 to 29.11mg GAE/100 g and antioxidant properties were determined by reducing power test (from 0.22 to 0.79) and DPPH assay (from 28.13 to 87.23%), while there was no difference regarding lactate. Our results provided new information about the levels of lactate, total polyphenols and antioxidant activity of selected commercial yogurts available on the Serbian market.