Starch and flour from various plants have been widely used for sundry applications, especially in the food and chemical industries. However, native starch and flour have several weaknesses, especially in functional, pasting, and physicochemical properties. The quality of native starch and flour can be improved by a modification process. The type of modification that is safe, easy, and efficient is physical modification using hydrothermal treatment techniques, including heat moisture treatment (HMT) and annealing (ANN). This review discusses the hydrothermal modifications of starch and flour, especially from various tubers and cereals. The discussion is mainly on its effect on five parameters, namely functional properties, morphology, pasting properties, crystallinity, and thermal properties. Modification of HMT and ANN, in general, can improve the functional properties, causing cracking of the granule surface, stable viscosity to heat, increasing crystallinity, and increasing gelatinization temperature. However, some modifications of starch and flour by HMT and ANN had no effect on several parameters or even had the opposite effect. The summary of the various studies reviewed can be a reference for the development of hydrothermal-modified starch and flour applications for various industries.

Soaking is an important step in making tempeh. Tempeh fermentation normally involves the natural presence of proteolytic bacteria capable of producing protease enzymes to break down peptide bonds in protein molecules. This study evaluated the protein and amino acid content of Jack bean tempeh (Canavalia ensiformis) soaked in distilled water during natural fermentation for 12, 24, 36, and 48 h. In this study, the crude proteins were determined using the Kjeldahl technique, amino acids were determined from protein hydrolysis, and proteolytic bacteria were enumerated for Total Plate Counts and further identified using Vitek 2.0 Compact System. The results showed that soaked Jack beans have higher protein and amino acid content, with sixteen essential and non-essential amino acids required for human bodies. The protein content of soaked Jack beans varied from 35% at 12 h to 32% at 24 and 36 h and 33% at 48 h. Soaking for 12 h yielded the highest amino acid concentration of 38,000 mg/kg L-glutamate, and the lowest of 14,000 mg/kg L-proline. Seven isolated bacteria showed proteolytic activity on Skim Milk Agar with a clear zone of 3.00 mm to 10.65 mm surrounding the colony. The bacteria identified were Pediococcus pentosaceus, Stenorophomonas maltophilia, Cronobacter sakazakii, and Klebsiella pneumonia ssp. In summary, Lactobacillaceae and Enterobacteriaceae were the predominant bacteria during tempeh fermentation, indicating the synergistic interaction between these microflorae during soaking conditions as part of their survival in this hostile environment.

Jack Beans are a type of high-protein legume that can produce high nutritional value. One of the processed superfoods from Jack beans is tempeh. Soaking is essential in making tempeh as a pre-fermentation process utilizing microbial enzymes to increase product nutrition. The metagenomic analysis is a novel technique to know microbial communities based on culture-independent microorganisms. This study aims to determine the diversity of microbes in the soaking process at 12 hours and 24 hours. This analysis found ten OTUs genera, namely Prevotella, Bacillus, Paenibacillus, Staphylococcus, Lactobacillus, Pediococcus, Saccharofermentants, Klebsiella, Pantoea, and Acinetobacter. Phylum Firmicutes is dominant in the soaking of Jack beans with a difference of 53.24% 12 h soaking time and 47.89% 24 h soaking time. This finding contributes to controlling the quality production of making tempeh.

Tempeh mold is tempeh starter mixed with legumes as a substrate. Generally, tempeh molds are Rhizopus sp. but they are not specific to a particular genus. This study aimed to identify and characterize the molds in "RAPRIMA" tempeh of LIPI Indonesia and overfermented (60 hours) koro pedang tempeh. The characterization method in this research utilized media-specific molds, analyzed by most chamber and microscopic, biochemical analysis with Analytical Profile Index (API-test), and molecular with ITS sequencing by PCR Product. The results showed that "RAPRIMA" tempeh yeast had total molds of 4.94 log CFU/mL on YMA media and 4.85 log CFU/mL on MEA media, while over-fermented tempeh had total molds of 4.84 log CFU/mL on YMA media and 4.60 log CFU/mL on YMA media. The characteristics of molds were black, white, and oval mycelia. The APItest analysis revealed that "RAPRIMA" tempeh and over-fermented tempeh yeast was Rhizomucor. The ITS sequencing by PCR products showed that it was Rhizopus microsporus. The genus mold characterization of RAPRIMA and over-fermented koro pedang tempeh was Rhizopus sp. and gives good physical characteristics.

Terasi, a traditional Indonesian seafood product made from shrimp, undergoes fermentation facilitated by a consortium of microorganisms, including Lactic Acid Bacteria (LAB) and yeast, which contribute to its distinctive umami flavor. This study investigates the microbial dynamics and production of key metabolites, including γ-aminobutyric acid (GABA), during terasi fermentation. Total Plate Count (TPC) and High-Performance Liquid Chromatography (HPLC) were used to monitor changes in glutamate and GABA levels, with glutamate increasing from 105.18 mg/mL on day 3–139.19 mg/mL on day 14, and GABA rising from 90.49 mg/mL to 106.98 mg/mL over the same period. Metagenomic analysis using high-throughput sequencing of bacterial 16 S rRNA identified Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidota as dominant phyla. While LAB populations remained relatively stable, yeast became detectable from day 4. Notably, core bacterial genera such as Vibrio, Macrococcus, Staphylococcus, Exiguobacterium, Jeotgalicoccus, Prevotella, Salinicoccus, Bacillus, Pseudarthrobacter, and Vagococcus were highly abundant and played significant roles in GABA production, likely due to their glutamate decarboxylase activity. These findings reveal a clear correlation between microbial succession and metabolite production, offering valuable insights into the fermentation process of terasi. This study enhances the understanding of traditional food fermentation and presents opportunities to optimize beneficial compounds in terasi products.